BLOOD PRESSURE 
CAUSE, EFFECT, AND REMEDY BLOOD PRESSURE 
CAUSE, EFFECT, AND REMEDY 
BY 
LEWELLYS F. BARKER, M.D. 
AND 
NORMAN B. COLE, M.D. 
D. APPLETON AND COMPANY 
NEW YORK :: LONDON :: MCMXXIV COPYRIGHT, 1924, BY 
D. APPLETON AND COMPANY 
FRINTAD IN THB UNITED STATES OF AMERICA PREFACE 
This volume goes thoroughly, but without tech- 
nicalities, into a subject that is of growing concern 
to both doctor and patient. The doctor is con- 
cerned because he sees more and more clearly 
the relation of abnormal blood pressure to heredity; 
to acute infectious diseases; to arteriosclerosis; to 
diseases of the kidney; and finally to old age 
and the maladies, so often fatal, incident to it. 
The non-medical man is concerned because he is 
learning that the development of high blood pres- 
sure is a process rather than a disease; that symp- 
toms develop rather late in its course; and that 
preventive measures must, therefore, be taken 
early. 
Blood Pressure gives the non-medical man in 
plain, readable English, the information he would 
like to have. 
Lewellys F. Barker, M.D. 
Norman B. Cole, M.D. CONTENTS 
CHAPTER PAGE 
Preface v 
I. Misconceptions with Regard to Blood 
Pressure 1 
II. Heart and Blood Vessels 11 
III. The Factors Concerned in the Produc- 
tion, Maintenance, and Adjustment of 
Blood Pressure 26 
IV. "Normal" Blood Pressure; and Methods 
of Measuring Blood Pressure ... 44 
V. Influences Affecting Blood Pressure in 
Health 54 
VI. On Some Varieties of High Blood Pres- 
sure and Their Causes; Relations to 
Hardening of the Arteries .... 68 
VII. The Heart, the Kidneys, and the Brain 
in Patients Manifesting High Blood 
Pressure 94 
VIII. Low Blood Pressure ("Arterial Hypo- 
tension") 113 
IX. What to Do? 119 
Glossary 147 BLOOD PRESSURE 
CAUSE, EFFECT, AND REMEDY 
CHAPTER I 
MISCONCEPTIONS WITH REGARD TO BLOOD 
PRESSURE 
The subject of blood pressure is enjoying to-day 
what amounts almost to a vogue. It has come 
prominently before the medical profession of late 
and has had to yield up some of its secrets under 
the searching light of investigation. World-wide 
reports of these researches are crowding the medi- 
cal literature; physicians everywhere, possessed of 
this newer knowledge, are paying increased atten- 
tion to blood pressure and to the disorders con- 
nected, in one way or another, with it. As a result, 
one finds what one might expect to find, namely, 
that the patient is impressed by the stressing of 
this subject, new to him, especially when he finds 
that blood-pressure troubles are peculiarly incident 
1 BLOOD PRESSURE 
to the senescent years. He looks then at others of 
his own age about him and discovers, in conversa- 
tion, that they, too, have been warned about their 
blood pressure. He even finds articles about blood 
pressure in the popular magazines. It finally be- 
comes more or less common knowledge to him that 
the matter of blood pressure is somehow mixed up 
with many of the serious and fatal diseases of 
middle and later life, and he becomes disturbed 
about his condition and perhaps downright fearful 
because of this new medical bugbear. 
Now fear is an inefficient sort of emotion, sel- 
dom bringing any advantage to its owner. The 
surest way to destroy it is to drag it out into the 
light of day and make it stand and deliver. Fre- 
quently it shrivels and reveals its meannesses, and 
disappears forever as a fear. There is always a 
real satisfaction in overcoming a fear. Conquer it 
and you secure a new peace of mind and perhaps 
also a hint as how best to avoid the attacks of other 
similar pestiferous causes of anxiety. 
The situation to-day with regard to blood pres- 
sure is a case in point. Before the non-medical 
man has heard the subject mentioned many times 
2 MISCONCEPTIONS 
he has learned to associate it with such dreaded 
things as Bright's disease, apoplexy, and serious 
heart disturbances. He knows, too, that these 
maladies increase in frequency in the second half 
of life and he becomes more and more anxious to 
know something about this "terrible" blood pres- 
sure and particularly how he may escape its dan- 
gers. The medical fraternity is just as anxious to 
tell what it knows about the subject, admitting all 
the time that its knowledge is yet imperfect, in order 
that these insidious foes of later life may be caught 
in the beginning of their work and rendered innocu- 
ous. Such a course is but in line with the whole 
trend of preventive medicine to-day. Prevention 
is coming to be of far more importance than cure. 
Indeed, it is easier; and economically, at least, it 
is of prime importance in the whole field of medi- 
cine, for sickness is far more costly to the nation 
in the loss of work and wages than all the perils of 
field and flood added together. One need only think 
of the conquest of smallpox, of yellow fever, of 
typhoid, and of malaria, to be convinced of the 
financial value of preventive medicine. 
But though the gospel of prevention of disease 
3 BLOOD PRESSURE 
has become an integral part of the physician's 
creed, it creeps but slowly into the code of the 
non-medical man. He is all too accustomed, espe- 
cially in America, to disregard his physical being 
until symptoms that will not be denied make it 
plain to him that something is the matter with him. 
This is the sad story of cancer and of tuberculosis. 
It is the layman's right, therefore, to have at his 
disposal such information as will help him to avoid 
the beginnings of disease; and, equally, it is his 
duty to inform himself of preventive measures, to 
the end that he may live out his threescore years 
and ten in comfort. Not less is the obligation of 
the physician to put his knowledge before the public 
in a simple and understandable form. Only thus 
does he perform his whole duty as a physician. 
It is always wise, before building, to clear the 
ground of obstructions, and there are two main 
misconceptions with regard to blood pressure that 
must be disposed of. 
The first misconception is that the subject of 
blood pressure is new, or that there is something 
new about it that constitutes a hitherto unknown 
menace to the health of the nation. Nothing could 
4 MISCONCEPTIONS 
be farther from the truth. Appendicitis was not 
a new disease in the last two decades of the nine- 
teenth century, though only then was it recognized. 
From time immemorial it has been known that 
blood vessels bleed when cut; the dullest can argue 
the cause as some sort of pressure within the blood 
vessels. When Harvey discovered the circulation 
of the blood and published his work, De Motu 
Cordis, in 1628, he recognized the fact that the 
heart propelled the blood by exerting intermittent 
pressure upon it. Medical investigation moved 
slowly in those days, and it was not until more 
than a century later, in 1733, that Stephen Hales, a 
clergyman, demonstrated and measured accurately 
the blood pressure in the arteries of a horse. Ran- 
dom observations were made from time to time, 
but it was only in the last quarter of the past cen- 
tury, that golden era of medicine, that observations 
of blood pressure could be made without opening 
the arteries and so became applicable to man. 
Indeed, routine estimations of blood pressure have 
become possible only in the last few years, with 
the development of the handy little arm-band, pump, 
and pressure gauge combination now so familiar; 
5 BLOOD PRESSURE 
so that, in a sense, our clinical knowledge of blood 
pressure is new. This is quite different from say- 
ing that disorders of the pressure are new. They 
are not. It is only the understanding of them that 
is new-an understanding brought about through 
an inconceivable number of observations and ex- 
periments by all manner of medical men in all 
parts of the globe. One might as well say that the 
revolution of the earth is new because it has been 
discovered within the memory of man. No one 
would be so silly as to believe such an assertion; 
and no one need fear any new threat against life 
from his circulatory system. Rather should we all 
rejoice that an old danger has been recognized and 
branded for what it is and that we are slowly but 
surely getting at the causes of it; and so making 
our way toward its prevention. 
The other misconception that blood pressure, in 
and of itself, is something wrong is easily disposed 
of. No fluid moves onward unless there be pressure 
of some kind upon it. The brook flows down its 
bed because of hydrostatic pressure dependent upon 
gravity. The geyser spouts, water moves through 
its pipes, blood through its vessels only in obedi- 
6 MISCONCEPTIONS 
ence to some compulsion. Without pressure of 
some kind or degree there could be no circulation, 
and hence, in the case of the body, no life. There 
is nothing that should alarm in the mere fact of 
blood pressure; it is a physiological necessity. But 
the blood pressure must remain within certain 
limits if health is to be conserved. In the plumbing 
of a house the pressure must be great enough to 
overcome gravity and the friction of the moving 
water against the inside of the pipes; and yet not 
so great as to burst the pipes. The limit of varia- 
tion is evidently wide. So, in the body, the blood 
pressure may vary a good deal, and does vary, 
under many different conditions, without becoming 
abnormal. It is only when it is raised or lowered 
beyond the limits of its normal swing, and particu- 
larly when it is maintained permanently or for 
some time at that abnormal figure, that any concern 
need be felt. 
Further, the pressure varies not only from time 
to time, but also from one part of the circulatory 
system to another. It is highest in and near the 
heart; lower as the smaller arteries are reached; 
and lowest in the veins. These phenomena are, of 
7 BLOOD PRESSURE 
course, true of any circulation. But now conies a 
marvel: delicate apparatus exist within the body 
by which the blood pressure may be so varied 
locally as to afford more or less blood to individual 
organs. Were it not for these normal local shifts 
in pressure always going on in the body with 
changing activities and moods it would indeed go 
hard with the organism and its balance. Now the 
stomach demands more blood for the purpose of 
carrying out its work of digestion; now the brain, 
in thinking; now the muscles, in their activities. 
All over the body are organs which, called upon 
to increase their activities, ask for more nutrition 
and more oxygen and require a greater flushing 
away of waste products. Just as more freight cars 
must be sent to the points of greatest commercial 
activity, so must more blood be provided for active 
organs; just as centers of trade change from one 
part of the country to another, so do the centers 
of greatest organic demand in the body change. 
And in order that the body may be ready to send 
extra blood to any given organ at a moment's warn- 
ing, the whole blood content of the body is held 
8 MISCONCEPTIONS 
always under a certain amount of pressure. This 
is sensible; for it is much easier to open the flood- 
gates of a certain organ to an already existing 
pressure than it would be to create an increase of 
pressure instantly at that one point. The mecha- 
nism of these local adaptations of pressure and flow 
are matters for a later chapter; mention of them 
here is merely to emphasize the fact that blood 
pressure is normally subject to variations. 
With the foregoing paragraphs in mind we must 
acknowledge at once that blood pressure is in itself 
a normal phenomenon; that it is necessary to the 
maintenance of circulation and of life; that in 
degree it varies from one part of the body to an- 
other with changing bodily needs; that even at any 
one point in the body it varies from hour to hour 
and even from minute to minute. We must remem- 
ber, however, that these fluctuations, though some- 
times surprisingly large, lie within certain fairly 
well-defined limits in the healthy person; and that 
it is only when the pressure figure transgresses 
those limits that it becomes harmful. The under- 
standing of what those limits are and when they 
9 BLOOD PRESSURE 
are transgressed and what the significance of the 
transgression is leads far into realms not yet well 
charted. Certain principles, however, stand out 
and may be stated. They involve an understanding 
of the normal mechanism of the circulatory system. CHAPTER II 
HEART AND BLOOD VESSELS 
In the preceding chapter, an analogy was drawn 
between the circulation of the blood in the body 
and the circulation of water in the pipes of a city 
water-supply system. The analogy holds good, 
however, only up to a certain point; beyond that 
the divergence of the two systems becomes so great 
that comparisons fail. The chief difference is 
that one system is inanimate, with rigid tubes and 
predetermined flow and pressure; whereas the other 
is animate, with living tubes capable of expansion 
and contraction, with a pulse which becomes auto- 
matically adjusted in its rate and volume to the 
immediate necessity, and with such a marvelously 
accurate and rapid reciprocal adjustment between 
heart and vessels that, in the absence of unusual 
outside influences, the circulation is ever main- 
tained at its maximum efficiency. Since the blood 
pressure is primarily dependent upon the function« 
11 BLOOD PRESSURE 
of the heart and blood vessels, some understanding 
of the architecture of the circulatory system and 
of the methods by which it works is necessary before 
we attempt further to discuss the blood pressure 
itself. 
The primary motor of the circulation is, of 
course, the heart. Though a comparatively simple 
one, it is a highly efficient pump, built almost 
entirely of muscle. It contains several chambers 
through which the blood stream is directed always 
onward because of the interposition of valves that 
prevent a backward flow. The onward motion of 
the blood is intermittent and is produced by the 
periodic contraction of the walls of the heart-cham- 
bers themselves; when the walls contract, the size 
of the chamber is diminished; hence the contained 
blood is pressed out of it. A complete vertical 
partition divides the heart into right and left halves, 
much after the fashion of a pair of modem duplex 
apartments. Each half contains an upper chamber 
(auricle) and a lower chamber (ventricle); the 
auricle receives the blood from the veins and 
passes it on to the ventricle; and the ventricle then 
propels the blood into the arteries. The heart is, 
12 HEART AND BLOOD VESSELS 
thus, essentially a pair of similar pumps lying side 
by side, each with two chambers, one above the 
other. For a moment it will be convenient to disre- 
gard the right side or half of the heart and to 
consider the left side or half only. The left auricle, 
then, receives the blood from the veins of the lungs, 
passes it downward through a valve to the left 
ventricle, which, contracting in its turn, forces the 
blood out through another valve into a large arterial 
vessel called the aorta. The aorta gives off branches 
almost immediately known as the arteries to the 
head and to the arms; it then continues downwards 
along the spinal column, giving off other branches 
to the internal organs as it goes, itself becoming 
gradually much reduced in size until it splits at last 
into the two great arteries that supply the legs with 
blood. Each of these arterial offshoots branches, 
exactly as does a limb of a tree, into an ever- 
increasing number of smaller and smaller vessels 
with thinner and thinner walls until every part of 
the body is supplied with a multitude of tiny 
vessels, called the arterioles. Thus far in its 
course from the lungs the blood has been merely 
in transit; now it must yield its oxygen and its 
13 BLOOD PRESSURE 
nutrition to the tissues and receive waste products 
from them; consequently an even simpler form of 
blood vessel becomes necessary in order to facili- 
tate the exchange of liquids and gases. The arte- 
rioles, already enmeshed in the depths of the 
various organs, accordingly divide still further into 
tiny vessels with walls so thin that they are hardly 
visible even under the microscope; and with caliber 
so small that the tiny cells of the blood must pass 
through in single file. Years ago the name "capil- 
laries" was given to these tiniest, shortest vessels 
by the older anatomists, who saw in them a resem- 
blance to short sections of a hair! Here in the 
inmost recesses of every organ occurs the vital 
interchange of the life-giving substances (including 
food and oxygen), carried in the blood and the 
waste products (including carbon dioxide) of which 
the tissues must quickly rid themselves. The barter 
takes place in an amazingly short interval of time 
and space. The blood, thus impoverished of food 
and oxygen and loaded with waste products, must 
now be hurried on again for purification and replen- 
ishment. Each capillary merges in a tiny vessel 
with somewhat thicker walls, known as a small vein 
14 HEART AND BLOOD VESSELS 
or venule. This joins its neighbor to make a larger 
vein, and as this union of one pair meets and unites 
with that of another, the resulting vessels become 
larger and larger, much as streams increase by 
confluence on their way to the sea; the union of 
ever larger veins continues until at last two great 
veins (the superior and inferior vena cava) are 
formed (one from the head and arms, the other 
from the lower half of the body), which together 
pour the entire blood stream into the auricle of the 
right side of the heart. Thence, just as on the other 
side of the heart, the blood passes through a valve 
into the ventricle and is pumped into and through 
the arteries and capillaries of the lungs, where it 
gives off carbon dioxide and receives new stores 
of oxygen. Returning through veins from the lungs, 
it is led directly to the auricle of the left side of 
the heart and the circle is thus completed. The 
part of the system from the left ventricle through 
arteries, capillaries and veins to the right auricle 
is known as the "greater or general circulation," 
whereas the part of the system from the right ven- 
tricle through the lungs to the left auricle is known 
as the "lesser or pulmonary circulation." 
15 BLOOD PRESSURE 
It has been said above that a blood vessel is a 
living thing, capable of contraction and of expan- 
sion; that is, its caliber, or lumen, can be decreased 
or increased. These changes in caliber occur prin- 
cipally in the arteries and only to a much less 
extent in the capillaries and veins. The contraction 
is accomplished by the tensing, under nerve control, 
of tiny little muscle fibers which run in a circular 
fashion within the walls of the arteries. Through 
nerve control the tiny muscles can be made to relax 
and to allow the vessels to dilate on the one hand, 
and on the other hand they can be made to contract 
also through nerve control so that less blood can 
pass through. The presence of this muscular layer 
accounts for the thickness of the arterial walls as 
compared with those of the veins, in which the 
musculature is so delicate as to be almost lacking. 
The largest relative amount of muscle tissue is 
found in the smaller arteries and arterioles, a fact 
which is of prime importance in the maintenance 
of blood pressure, as later will be seen. Yet even 
these sturdy little muscles would not be able to 
withstand the very large expansile force exerted 
in the larger vessels, already full of blood, as the 
16 HEART AND BLOOD VESSELS 
heart suddenly throws into them, again and again, 
a large additional volume of blood, were it not for 
the presence in the wall of the vessel of many elastic 
fibers. These allow the walls of the vessel to give 
at the moment of passage of the pulse wave and 
enable it to return to its normal size as soon as the 
wave has passed.1 Finally, a layer of (dense) 
fibrous tissue surrounds the vessel and lends 
strength to the whole structure. 
The necessity for such a combination of strength 
and elasticity in the arteries is easily realized when 
it is considered how great a volume of blood they 
receive from the heart at each beat. If the forward 
motion of the blood is to be passed on to the smaller 
arteries with their thinner walls their larger brothers 
must absorb, by means of elasticity, at least some 
of the expansile force of the pulse wave. To drop 
for a moment into technical terms, the kinetic 
energy of the heart must be transformed, tempo- 
rarily, to some extent into potential energy. The 
1 Very likely the muscular layer contracts again immediately 
behind the pulse wave and so helps the heart to move the blood 
stream onward. In some of the cold-blooded animals, for instance, 
certain of the vessels show definite rhythmical contractions and 
thus take some of the burden of propulsion off the heart. 
17 BLOOD PRESSURE 
result is ideal. The intermittent advance of the 
blood in the large arteries is changed gradually 
into a steady onward flow as the smallest arteries 
(or arterioles) and capillaries are reached. The 
process is aided by the ever-increasing total cross 
area of the bed of the blood stream toward the 
periphery due to the continuous branching of the 
vessels. It is estimated that the total cross area 
of the arterioles is something like eight hundred 
times that of the cross area of the aorta near the 
heart. The broader the stream the slower and the 
smoother the flow. By the time the blood reaches the 
capillaries, therefore, its progress is leisurely and 
the pulse wave, has been lost-flattened out, as it 
were, by the smaller arteries and arterioles. On the 
far side of the capillary system there is nothing to 
reconstitute the pulse wave, and the blood returns 
to the heart through the veins with a steady motion, 
accelerated somewhat by contraction of the muscles 
in the walls of the veins and more by the creation 
of a vacuum within the chest during breathing. 
The tiny muscles in the walls of the blood vessels, 
like muscles elsewhere in the body, contract only 
when an impulse reaches them through a nerve. 
18 HEART AND BLOOD VESSELS 
Now there is one system of nerves which derives 
its impulses from the thinking part of the brain; 
messages pass along them only at the command 
of the "will" and are carried to muscles which are 
under voluntary control, such as those which move 
head, trunk, limbs, eyes, tongue, etc. This system 
of nerves is called the "cerebrospinal." The other 
system of nerves, different and separate from the 
first in many respects, yet intimately connected 
with it by many cross-overs, supplies those muscles 
which are not under the control of the will. These 
nerves form the sympathetic nervous system; they 
run to the musculature of the internal organs, such 
as the stomach, intestines, bladder,heart, diaphragm, 
glands, blood vessels, etc. It is plain that these 
organs are not under the direction of the "will." 
It is plain, for instance, that one cannot voluntarily 
initiate, govern, or stop the contractions of the 
stomach and intestines that occur during digestion 
by thinking about them. Thinking about digestion 
may influence it indirectly through the emotions 
and the sympathetic nervous system but not directly 
through the cerebrospinal nervous system. It is 
impossible voluntarily to stop breathing for longer 
19 BLOOD PRESSURE 
than a certain time, or voluntarily to make the 
heart beat faster or slower. Sweating, the produc- 
tion of saliva, the manufacture of urine, or of bile 
or of pancreatic juice, to name only a few of the 
very large number of complex vital processes, are 
fortunately carried on automatically, not volun- 
tarily. If it were not so, if the body were so 
constituted that conscious thought had to be given 
to the direction of all these activities, man would 
have no time for anything except to keep his bodily 
machinery properly at work. He could never even 
dare take time to sleep, for the beating of his 
heart and his breathing would stop at once. Even 
if it were possible for man to master all the intrica- 
cies of the vital functions, if these were to be left 
to him to control voluntarily, he would soon die 
from sheer exhaustion and the race would come to 
an end abruptly. 
The sympathetic nervous system is not only the 
mechanism for the perpetuation of the automatic 
functions but it also can hasten or retard these 
functions; it plays one function against another 
so as to favor the maintenance of that harmony 
and equilibrium throughout the body that is neces- 
20 HEART AND BLOOD VESSELS 
sary for health. The delicate, exact, and instant 
coordination of the various automatic functions, 
for the benefit of the body as a whole, is so smoothly 
accomplished that no one is conscious of it and 
few even think of it; yet the wonder is as solemnly 
impressive as the ordered movements of the stars 
or as the growth of the white lily from the black 
muck. Thought of it can lead only to reverent 
awe and to profound admiration. Man's mind 
has never conceived of a machine half so subtle 
and delicate, nor half so sturdy, efficient, and 
capable of satisfactory function in the face of 
almost overwhelming odds of excess and disease. 
The story of the adaptive phases that are observable 
in the circulatory system in health will be told in a 
later chapter; here we are concerned merely with 
the mechanism of adaptation and its relations to 
the heart and the blood vessels. 
Healthy muscle possesses what is called tone, 
that is, a state of continuous slight contraction that 
keeps it in readiness to perform grosser movements 
at the behest of the nerves. A muscle without tone 
will not respond to stimulation; naturally, such a 
condition never occurs in healthy living muscle, 
21 BLOOD PRESSURE 
although the degree of tone may, at times, vary a 
good deal. The condition is analogous, in a way, 
to the tenseness of the sprinter at the tape as he 
awaits the sound of the starter's gun. The tone of 
all musculature is maintained by the continuous 
discharge into it, by way of the nerves, of feeble 
impulses from the nervous centers. In the blood 
vessels, the term tone is transferred in a rather loose 
way from the description of the condition of con- 
traction in the muscular layer of the vessel to the 
condition of the vessel itself; thus, for brevity's 
sake, we speak of the tone of a vessel or, in a still 
broader sense, of vascular tone throughout the 
circulatory system. Obviously, an increase in tone 
means a decrease in the size of the vessels, and vice 
versa. Since heart and vessels have no outlet except 
into each other and therefore form what is called a 
closed system, it is evident that a contraction of 
the vessels of the system means a diminished 
capacity in the system as a whole. The converse, 
however, is much more important: with lowered 
vascular tone and dilatation of the vessels the 
capacity of the system is enormously increased. 
Recall the large disparity between the total cross 
22 HEART AND BLOOD VESSELS 
section of the arterioles and that of the aorta; and 
remember that variations in tone are most marked 
in these same arterioles; and it will be obvious at 
once that a very slight change in tone must involve 
a considerable change in the general vascular 
capacity. 
The relation of the volume of blood to the 
capacity of its containing vessels may now be con- 
sidered. It will be recognized, of course, that the 
circulation cannot be maintained without pressure 
any more than water will flow through a system of 
pipes without pressure behind it. Hydrostatic 
pressure, of course, would remain, even if the 
pumps should fail; but this is just another way of 
saying that gravity will cause the water or the 
blood to seek the lowest level in the system and 
remain there. The blood volume changes but 
little, if at all; any such descent of blood, therefore, 
in obedience to gravity and unopposed by vascular 
tone, would quickly leave the higher parts of the 
body devoid of sufficient blood to carry on their 
functions. Under such conditions life would very 
quickly cease. Rabbits die when suspended by 
the ears for a period of time; since their vascular 
23 BLOOD PRESSURE 
tone when they are suspended is not strong enough 
to oppose the force of gravity, the blood collects 
more and more in the lower portions of the body 
and leaves the brain without sustenance enough to 
support life. In such cases most of the blood 
collects in the atonic vessels that feed and drain 
the organs of digestion in the abdomen. During 
their active period of work these digestive organs 
require an enormous quantity of blood flowing 
through them not only to support their activity but 
to carry away the products of digestion to be de- 
livered to the rest of the body. Accordingly, the 
network of vessels in the digestive organs is par- 
ticularly rich and the vessels themselves are of 
relatively large size. It has been frequently stated 
and accepted that these vessels, if they were to be 
deprived of tone, would attain to a capacity that 
would hold all the blood in the body, so that it is 
theoretically possible for a person to bleed to 
death into the veins of his own abdomen. 
Against such a fatality, the body has a bulwark 
in the phenomenon of tone. It is the province of 
the blood vessels to contract upon the contained 
blood not merely to that degree at which the blood 
24 HEART AND BLOOD VESSELS 
exactly fills all the vessel spaces throughout the 
body but to a further degree at which the blood is 
actually put under pressure. The process is exactly 
similar to that of filling a rubber ball full of water, 
sealing the opening, and squeezing the ball. The 
water within is then under pressure and it will 
squirt out if a hole be punched in the ball, just 
as blood will flow out of the circulatory system 
if a vessel be cut. It is this pressure, exerted by 
the heart and the contraction of the walls of the 
blood vessels upon the contained blood with vary- 
ing intensity, that we speak of as "blood pressure." 
We shall attempt to follow the fluctuations of this 
pressure in health and in disease and shall try to 
determine what bearing changes in blood pressure 
have upon the maintenance of health. CHAPTER III 
THE FACTORS CONCERNED IN THE PRODUCTION, 
MAINTENANCE, AND ADJUSTMENT OF 
BLOOD PRESSURE 
Of the several factors that contribute to the 
maintenance of blood pressure in the circulatory 
system the three most important are the contractile 
power of the heart, the elasticity of the arterial 
walls, and the peripheral resistance offered chiefly 
in the arterioles to the onward flow of blood. Other 
factors enter, such as gravity, barometric pressure, 
viscosity, and total quantity of blood; but they are 
of secondary importance and need not concern us 
here. 
The three main factors are so intimately inter- 
related and so finely adjusted one to another that 
it is scarcely possible to describe one without 
reference to the others. But certain salient facts 
stand out and may be concisely stated. The heart, 
for instance, is the prime mover of the blood and 
the principal source of blood pressure. Without 
26 FACTORS IN BLOOD PRESSURE 
some applied energy the blood would come to rest 
in the most dependent parts of the circulatory sys- 
tem under no pressure except that produced by 
gravity. But with each heart beat blood is forced 
into the arterial side of the system, resulting in an 
increase of pressure there and a decrease of the 
pressure in the veins behind the heart. If no other 
force were considered and no resistance were 
offered to the onflow of blood through the arteries, 
the arterioles, the capillaries, and the veins, back 
to the heart, the intermittent rise of pressure with 
each heart beat would be distributed equally 
through the circulation and the pulse beat would 
travel the whole route and reappear at the heart 
on the venous side. Such, we know, is not the case, 
for there is no pulse in the veins. The reason for 
this has been discussed in Chapter II. There we 
pointed out how, through branching of the arterial 
tree, the bed of the blood stream widens as its 
distance from the heart increases, permitting an 
ever slower and calmer flow of blood; and at the 
same time we tried to show how the elasticity of 
the vessel walls damps the pulse wave until it be- 
comes lost in the arterioles and capillaries, just as 
27 BLOOD PRESSURE 
wavelets on the shore of a lake are lost amid the 
yielding rushes. Now still another conception 
must be added. Even in the generous width of the 
bed of the smallest arteries the blood is not allowed 
to flow on unimpeded. The tone of the arteriolar 
walls is a state of continuous mild contraction, so 
that within the arterioles the blood is always under 
some pressure. These small vessels stand as gates 
at the outflow of the blood from the arterial system; 
these gates oppose the outflow to some extent, and 
thus antagonize the action of the heart at the other 
end of the arterial system. The heart forces blood 
into the arteries; the arterioles oppose its free escape 
from them. Between the two, arterial blood is ac- 
cordingly kept continuously under tension; in other 
words, "blood pressure" is created and maintained. 
We dare not dismiss the subject of blood pres- 
sure, however, with a mere account of the gen- 
eral factors concerned in its creation and main- 
tenance. We must discuss also its phases and 
variations, of which the simplest are evidently those 
occasioned by beats of the heart and the intervals 
between them. The blood pressure will obviously 
reach its lowest point ("minimal pressure") during 
28 FACTORS IN BLOOD PRESSURE 
diastole (rest period) of the heart and after the 
pulse wave created by systole (contraction period) 
of the heart has passed through the arteries and 
died out in the smaller arterioles. The pressure 
then becomes stationary at its low point for a mo- 
ment until another systole sends another surge of 
blood into the arteries. As the pulse wave passes 
any given point the pressure rises there again to 
its high point ("maximal pressure"), only to fall 
once more as the wave passes beyond it. Thus 
there is a fluctuation of pressure from minimum 
to maximum and back again with each cardiac 
cycle. Obviously there must be many levels of 
pressure during systole as well as during diastole. 
The high point of blood pressure is called the 
"maximal systolic pressure" and the low point 
the "minimal diastolic pressure." For the sake of 
brevity such high and low points are often referred 
to by physicians as "systolic pressure" and "dias- 
tolic pressure," respectively, without the use of the 
qualifying adjectives. 
If the flow of blood were through rigid tubes 
instead of elastic tubes the maximal systolic pres- 
sure would be much higher than it is really found 
29 BLOOD PRESSURE 
to be, and would be, except for diminution through 
friction against the walls of the vessels, about the 
same as that within the heart during its contraction. 
Again, were it not for the arterioles, which prevent 
free egress of blood from the arteries to the veins, 
the diastolic pressure would fall to zero. Just as 
the arterioles maintain the diastolic pressure at a 
point above zero, so some agency must be present 
to absorb some of the energy of the heart's beat 
and to prevent the systolic pressure from rising 
too high. This agency is the elasticity of the vessel 
walls. Each time the heart throws a quantity of 
blood into the aorta, that vessel yields to the in- 
creased pressure by undergoing dilatation. As 
the pulse wave passes along and spreads into the 
arterial branches, the vessels enlarge for a moment 
to permit its passage without damage to themselves, 
exactly as the bulge slowly progressing down the 
length of a snake's body denotes the passage of 
the latest unfortunate mouse. A finger resting long 
enough upon the reptile's body would become aware 
of the passage of this slow wave, just as the finger 
on the artery at the wrist is aware of the far quicker 
passage of the arterial pulse wave. The wave, or, 
30 FACTORS IN BLOOD PRESSURE 
as it is commonly called when perceived by the 
finger, the "pulse," can be easily felt in the large 
vessels of the neck; less easily, though still plainly, 
in the smaller radial artery at the wrist; and ever 
less easily as still smaller arteries are selected for 
examination by the palpating finger. 
Eventually, as we have seen, the wave becomes 
lost in the arterioles and capillaries. A small part 
of this loss is due to the "petering out" of the wave 
as it reaches the ever-widening stream-bed of the 
smaller vessels; but by far the greater part of 
the wave is stifled by the yielding of the arterial 
walls-damped out by it, as echoes in a concert 
hall are silenced by yielding felt. It is important 
to note that the damping process is not a suppres- 
sion of the energy that originates in the heart beat, 
appears in the form of the pulse wave, and causes 
the rise of blood pressure; the energy merely under- 
goes conversion into another form, kinetic energy 
being transformed temporarily into potential 
energy. The rhythmic contraction of the heart is 
rather violent and the systolic pressure within its 
ventricles is too high to be withstood successfully 
by the smaller vessels. Not only must the high 
31 BLOOD PRESSURE 
pressure be toned down; but at the same time the 
pulse wave must be converted into a steady flow 
in order that the nutritional benefits of the blood 
to the tissues may be mediated through the capil- 
laries. Precisely these conditions are realized 
through the agency of the elasticity of the vessel 
walls. 
The larger arteries are something more, then, 
than mere pipes for the transmission of blood; they 
are also active agents in the circulation, having a 
definite mission to perform in addition to mere 
conduction. By yielding to the wave of systolic 
pressure by dilatation they convert most of the 
kinetic energy (the proportion has been estimated 
to be as high as 99 per cent) of the heart beat into 
latent energy. The latter, in its turn, comes into 
play as soon as the peak of the pulse wave has 
passed and the pressure begins to fall rapidly 
behind it. Because of the same elasticity that 
enabled the arteries to dilate without harm, they 
tend now, in the face of the falling pressure, to 
return to their usual size; and in so doing they 
exert added pressure upon the contained blood. It 
is very likely, although not yet proved, that the 
32 FACTORS IN BLOOD PRESSURE 
musculature in the vessel wall is stimulated at 
the same time and adds its "squeeze" to that of the 
elastic fibers. In response to this added pressure 
the blood tends to move and since its return to 
the heart is blocked by the aortic valves, it finds its 
outlet toward and through ever smaller arteries 
and the capillaries. In so far as the action of the 
elastic fibers shares in this result, some, if not all, 
of the latent energy stored by the vessel walls as 
the pulse wave passes is now returned as kinetic 
energy; thus the larger arteries come to share with 
the heart the burden of imparting forward motion 
to the blood stream. The enormous importance of 
this physiological arterial supplement to the work 
of the heart will become evident when we enter 
upon a discussion of the conditions that are asso- 
ciated with diminution or loss of the elasticity of 
the vessel walls; for we shall see that then upon the 
much-enduring heart there has been placed an 
added burden that sooner or later results in impair- 
ment of that organ's efficiency. 
In some respects, the work of the hydraulic ram 
is a good illustration of the mechanical action of 
the arterial circulation. In a ram water is forced 
33 BLOOD PRESSURE 
intermittently (as by the heart beat) into a cham- 
ber partly filled with air. The air is compressed, 
damping some of the inrushing energy of the water, 
just as elasticity of the vessel walls damps some 
of the heart's energy. Water flows out of the air 
chamber of the ram against the resistance of the 
column of water in the pipes that leads up to 
the tank, just as blood flows onward in the arteries 
against the resistance of the arterioles. The move- 
ment of the water, like that of the blood in the 
arteries, is of two kinds; first, a sudden onward 
lunge due to the intermittent delivery by the pump 
of a large quantity of liquid; and, second, when 
the lunge is over, a slower, more steady forward 
motion, which is imparted by the pressure of the 
elastic air, the latter pressure corresponding to 
the contraction of the elastic and muscular fibers 
of the blood vessels. If the delivery pipe of the 
ram be long enough, the lunge will eventually 
disappear so that the flow becomes steady, just as 
it does in the human circulatory system. 
To complete the picture of the variations in 
pressure in the arterial system during one cardiac 
cycle, a third factor must be considered, namely, 
34 FACTORS IN BLOOD PRESSURE 
variations in the peripheral resistance offered by 
the arterioles. The rise of the blood-pressure 
curve is, of course, rapid, since the heart delivers 
its blood suddenly to the vessels; the fall is com- 
paratively slow, due partly to the prolonged action 
of the elastic walls of the arteries and partly to 
the obstruction of the outflow offered by the arte- 
rioles. If it were not for friction of the rather 
sticky blood against the vessel walls, friction which 
eats up a good deal of energy, the fall in the pres- 
sure would be exactly equal to the difference 
between the energy represented by the pressure of 
the blood in the left ventricle during systole and 
that represented by the pressure in the arterioles 
and capillaries. With suitable allowance for the 
element of friction, the transformations of energy 
that actually take place are easily accounted for. 
The low point of the pressure curve, when meas- 
ured, yields the figure for the minimal diastolic 
pressure. We have seen that the systolic pressure 
is determined by the force and frequency of the 
heart and the condition of the arterial walls; and 
we can now see that the minimal diastolic pressure 
point is determined by the amount of resistance 
35 BLOOD PRESSURE 
offered by the arterioles to the oncoming blood. 
The minimal pressure is the point at which the 
falling blood pressure becomes stationary toward 
the end of diastole; not until the advent of a 
new impulse from the heart does the pressure 
within the arterial system rise again. 
Considerable space has been devoted to the parts 
played by the heart and the larger arteries in the 
production and maintenance of arterial blood pres- 
sure and the role of the resistance offered by the 
arterioles has perhaps been sufficiently indicated. 
We have seen that the systolic pressure is highest 
in the ventricles of the heart during systole and 
falls gradually as the smaller arteries are reached. 
A still greater fall occurs beyond the constriction- 
system of the arterioles, and in the thin-walled 
capillaries the blood pressure becomes very low 
indeed. We are not here particularly concerned 
with the pressure levels in the veins, except to note 
that whenever dilatation of arterioles and capil- 
laries occurs, pressure is lowered on the arterial 
side of the circulation and raised on the venous 
side. The return flow of blood to the heart through 
the veins is accomplished not so much by pressure 
36 FACTORS IN BLOOD PRESSURE 
behind it as by certain other mechanical factors. 
The veins in the lower part of the body, for instance, 
are provided with valves to prevent back flow. 
Again, many of the veins are rather near the sur- 
face of the body and are subject to muscular 
pressure during bodily movements; such pressure 
from without is easily exerted, since the veins have 
thin muscular and elastic coats and are easily col- 
lapsible, in contradistinction to the arteries, which 
always maintain their tubular shape. Blood pres- 
sure is lowest in the large veins; indeed, it falls 
to and below zero in those large veins that traverse 
the chest, because within the chest, owing to the 
contraction of the diaphragm in the act of inspira- 
tion, there is created a partial vacuum, which 
accounts both for the entrance of air into the 
lungs and for the development of a negative pres- 
sure within the large veins. 
Thus far we have given a mere outline descrip- 
tion of the three main factors responsible for the 
existence of the blood pressure; the interrelation 
of these three factors is another story. This leads 
us to a consideration of some of the functions of 
the vegetative nervous system, for it is this system 
37 BLOOD PRESSURE 
that stands guard over fluctuations in blood pres- 
sure and correlates the various influences that affect 
it. A description of the complex anatomy of the 
vegetative nervous system is a matter for a large 
medical textbook; but, we are here concerned only 
with those parts of it that cause contraction or 
dilatation of the blood vessels and those which 
increase or diminish the rate of the heart beat, 
and we may disregard those parts of it that govern 
the functions of the internal organs. 
The vegetative nervous system is connected with 
the cerebrospinal nervous system (brain, spinal 
cord) and with the nerves of that system which 
carry sensory impulses to it and motor impulses 
away from it to the skeletal muscles; and each 
part of the vegetative nervous system is connected 
by many cross branches with other parts of the 
same system. From the brain it receives impulses 
that arise during emotions and moods or on the 
reception of impressions through the "five senses"; 
thus fear, anger, disgust, nauseating smells, terrible 
sights, and the like, may come to have an echo in 
variations of the blood pressure. Through other 
parts of the cerebrospinal nervous system it derives 
38 FACTORS IN BLOOD PRESSURE 
impulses dependent on stimulation of the organs 
of cutaneous, muscular and special sense and others 
dependent upon stimulation of the musculature. 
And the vegetative system itself is related espe- 
cially to what goes on not only in the blood vessels 
but also in the internal organs and the secretory 
glands. The vegetative nervous system is thus, as 
it were, the Associated Press of the body, with 
correspondents in every nook and cranny of the 
organism; it is a great correlating agent of all 
the bodily functions. 
As far as the circulation is concerned, the vege- 
tative nervous system carries at least two sets of 
fibers, known respectively as "vasoconstrictor" 
and "vasodilator" fibers. The former stimulate 
the muscular coats of the blood vessels to contract, 
whereas the latter cause the vessels to dilate. The 
vasoconstrictors are responsible for the maintenance 
of tone in the vessels and the impulses to that end 
emanate from the brain itself. The connections 
and mode of action of the vasodilators are less well 
understood, though their existence is beyond doubt. 
In the distribution to the heart, these two classes of 
fibers have their analogues in the accelerator and 
39 BLOOD PRESSURE 
inhibitory nerves, which respectively hurry or slow 
the heart's action. 
Enough, perhaps, has been said of the signifi- 
cance of the three main factors concerned in the 
production and maintenance of blood pressure to 
render unnecessary here anything more than a brief 
catalogue of the mechanisms through which these 
factors are interrelated through the mediation of 
the vegetative nervous system. The subject will 
crop out again and again in the pages that follow. 
The vegetative nervous system may raise the blood 
pressure by hurrying the heart, which then pours 
more blood per minute into the arteries; by increas- 
ing the tone of the heart muscle and hence the force 
of its contraction, with a similar result; or by 
increasing the tone of the muscular walls of the 
vessels and thus increasing the peripheral resistance 
in the arterial system. These activities may exist 
in various combinations; usually, and especially 
in transient emotional states, all three come into 
play. Under long continued conditions of mental 
or physical stress and strain the increase in tone 
of both the heart and the arterial vessels may be- 
come more prominent, in which event the heart, 
40 FACTORS IN BLOOD PRESSURE 
instead of adopting a permanently hurried rate, 
accommodates itself to the increased work by 
growing literally larger and more powerful. Other 
parts of the vegetative nervous system lower blood 
pressure by slowing the heart and by diminishing 
the cardiac and the vascular tone. If the great 
arteriolar bed suffers, in general, a marked lower- 
ing of tone, as in a common fainting attack, in 
surgical shock after anesthesia, or after a severe 
injury, the sympathetic system (a part of the vege- 
tative system) tries to maintain the pressure by 
hurrying the heart, in order to keep full the arteries, 
which are being depleted by a too rapid draining 
away of the fluid through the relaxed arteriolar 
gates. Again, after a heavy meal, the heart is 
stirred to more rapid action, for otherwise there 
would be a fall in blood pressure because of the 
fact that the arterioles in the digestive area (the 
most extensive arteriolar bed in the body) relax 
during digestion in order that more blood may flow 
through the active organs. Such physiological 
variations in pressure are seldom demonstrable 
with instruments, for the very good reason that 
the sensitive vegetative nervous system "catches" 
41 BLOOD PRESSURE 
the tendency to change before it has become pro- 
nounced and takes up its regulatory function of 
maintaining the pressure at a fairly uniform level. 
As a matter of fact, during digestion, the blood 
pressure usually rises a little, because the vegeta- 
tive system in its regulatory capacity not only 
counterbalances the tendency to fall but actually 
overcompensates a little. 
A compensation that is even more remarkable is 
observable among the vasoconstrictions and vaso- 
dilatations of the different arteriolar areas of the 
body. A lowered tone in one arteriolar area may 
be neutralized by a rise of tone in some other so 
that the general blood pressure is not changed. 
After eating, for instance, one feels a cold wind 
more than before, because the tiny vessels in the 
skin are sympathetically constricted, squeezing 
their blood out to some extent in order that it may 
be diverted to the active area of digestion. The 
relative lack of warm blood in the skin area is 
telegraphed to the brain by the sensory nerves and 
interpreted there as a sensation of cold. 
Many intricate adaptations within the domain of 
the blood pressure functions might be mentioned. 
42 FACTORS IN BLOOD PRESSURE 
They are all for a definite purpose, namely, the 
maintenance of efficient blood pressure. Maximal 
adaptability presupposes the existence of a heart 
adequate to its work, vessels with unimpaired walls, 
a normal degree of tone throughout the circulatory 
system, and a state of general physical and mental 
health that enables a normal vegetative nervous 
system to make the quick responses and to bring 
about the adaptive changes that are continuously 
being demanded. CHAPTER IV 
"NORMAL" BLOOD PRESSURE; AND METHODS OF 
MEASURING BLOOD PRESSURE 
The good, old, Latin word "normal" has come 
to be much abused of late-and that, by its friends. 
In old Italy "norma" meant a rule, a pattern, a 
carpenter's square-a measure by which other 
objects could be accurately delimited; in modern 
parlance its edges have been chipped and its cor- 
ners rounded until it no longer represents anything 
so definite as an inch or a right angle. It has been 
applied to processes and abstractions. It, so to 
speak, sits in judgment over matters as diverse as 
the rainfall in Peru, the number of passengers 
in the subway at 5 P. M., or the count of red cor- 
puscles in a cubic millimeter of blood. But it 
must always be remembered that the so-called 
"normal" is arrived at through a series of observa- 
tions of individual events. 
The method of ascertaining the "normal" can 
44 "NORMAL" BLOOD PRESSURE 
best be appreciated if we turn to concrete examples 
for illustration. Take, for instance, the tempera- 
ture. The newspaper tells its readers that the 
temperature for the preceding month was so many 
degrees above or below "normal." The statement 
is merely the result of the consideration of daily 
observations of air temperature during the same 
month extended over a period of years. All the 
fluctuations, reduced to a mean, yield an average 
figure, which is held to be the "normal" for that 
month. But no one believes for a moment that there 
will ever come a time when the temperature for 
that particular month will always conform strictly 
to that norm. Nor is any one disturbed about the 
thermometer if it shows variations of a few degrees 
to either side of the established norm. The man 
who got excited over an unseasonable drop of tem- 
perature and cried to his neighbors that the world 
was about to freeze up would be laughed to scorn. 
In other words, the normal temperature is recog- 
nized as merely the average temperature from 
which variations may be expected; and unless these 
variations are extraordinary they receive but little 
attention. As a matter of fact, the whole range of 
45 BLOOD PRESSURE 
variations of temperature in a given place and on a 
given date (as determined over a period of years) 
expresses the "normal" temperature for that place 
and date more accurately than any single figure can. 
The example of the air temperature as measured 
by the thermometer is fairly simple, for the factors 
that govern temperature are fairly well known, are 
relatively few in number, and are likely to interact 
with one another in the same manner time after 
time. In more complicated examples, the deter- 
mination of the normal may be much more difficult. 
As the complications increase, the idea of ascer- 
taining a "normal" as a point must be given up. 
Thus, it cannot be said with truth that the "normal" 
price of eggs is forty cents a dozen; although it 
might be true that in Washington County, Mary- 
land, in June, the normal price at the farm is forty 
cents, providing hawks, rats, and foxes are not too 
numerous, the cost of hen-feed is moderate, and 
the gapes are not too prevalent. But it would be 
much nearer the truth to say that the "normal" 
range of prices of eggs at that time and place was 
from thirty to fifty cents; any price outside those 
limits might reasonably be said to be "abnormal." 
46 "NORMAL" BLOOD PRESSURE 
Exactly the same reasoning applies to "normal" 
blood pressure, but to a much greater degree: for 
wherever a function of a living organism becomes 
the subject for the determination of a norm, the 
factors influencing the position of that norm are 
found to be so numerous, so diverse, and so little 
understood, that it is folly to put the finger at any 
one spot and to assert that there is the normal. 
Age, sex, inheritance, general physical health, 
weight, height, time of day, time since eating, 
climatic conditions, position of body, state of mind, 
and a thousand other things may affect the blood 
pressure. It is constantly varying up and down the 
scale, in accordance with bodily needs and condi- 
tions. "What is a normal blood pressure either for 
the individual or the species has never been and 
never can be determined, because the pressure must 
vary according to the calls of the system for more 
or less fresh blood." 1 
Let us, then, along with the original investigators, 
disabuse our minds of the old Latin meaning of 
"normal" as a definite, unchanging rule, or meas- 
1Moschcowitz (E.). "Pathology of Hypertension," Jour. A. 
M. A., Chicago, 1922, Ixxix, 1196-1200. 
47 BLOOD PRESSURE 
ure, and think of it rather as an elastic expression 
of a range of values that do not vary far enough 
away from the ascertained average to be called ab- 
normal. Better still, give up the use of the word 
"normal" altogether as applied to blood pressure, 
and substitute for it the term "average." To the 
man who is worried about his blood pressure, such 
a substitution very often brings a sense of relief. 
"Average" impresses the man in the street as a less 
strict term than "normal"; if he learns what aver- 
age blood pressure is he will not shy in alarm at 
the discovery that he experiences moderate varia- 
tions of pressure; and he will not assume that every 
man's pressure must be the same as his neighbor's. 
Besides, the term "average" is more accurate than 
"normal" for general application, for what is a 
"normal" pressure for one man may be quite "ab- 
normal" for another. Of course, it is accurate to 
speak of normal variations in pressure; but the 
use of the term "average" blood pressure connotes 
that such variations may occur and still be within 
normal limits. 
Blood pressure is commonly measured, in this 
country, with an instrument called the sphygmoma- 
48 "NORMAL" BLOOD PRESSURE 
nometer, so named because it measures the pressure 
of the pulse. It consists of a non-elastic arm-band 
or cuff (of leather or of stout cloth) within which 
is contained a flat but distensible (rubber) bag. 
The bag is connected with an air-pump (usually a 
rubber bulb) and with a pressure indicator; the 
latter may be an upright tube containing mercury, 
the height of the column of mercury in millimeters 
indicating the pressure; though more often an 
aneroid indicator is used. In either case, the read- 
ing of the pressure is in terms of millimeters of 
mercury. In practice, the arm-band with the flat 
rubber bag interposed is fixed firmly round a limb 
(usually the arm just above the elbow). Air is 
then pumped into the bag, which, against the re- 
sistance of the rigid arm-band, exerts its pressure 
on the arm, the amount of the pressure being regis- 
tered by the indicator. It is evident that the soft 
tissues of the arm will yield to this pressure, and 
that, among other structures, the large artery in the 
arm (the brachial artery) will be compressed. 
When the pressure in the cuff rises to a level equal 
to that existing within the artery, the vessel will 
collapse and the flow of blood through it will be 
49 BLOOD PRESSURE 
shut off; simultaneously, the pulse at the wrist will 
disappear. The pressure in the cuff is usually 
quickly raised to a level somewhat above that neces- 
sary for the obliteration of the pulse and then al- 
lowed slowly to fall. Meanwhile a stethoscope is 
placed over the artery at the bend of the elbow. 
At first nothing can be heard; but as the pressure 
falls slowly, the listener becomes aware of a sharp, 
snapping sound, denoting the passage past the con- 
stricting cuff of a bit of the pulse wave. The pres- 
sure in the cuff must now be equal to the maximal 
systolic pressure within the artery; the degree of 
pressure exerted is then read on the indicator and 
noted as the "maximal systolic pressure." Defla- 
tion of the cuff is then further continued, with 
variations of the sounds heard at the elbow until at 
last they practically disappear. At this point, or 
at a point just preceding when there is a sudden and 
marked change in the sounds, the pressure in the 
cuff is just equal to that maintained in the artery 
between the successive pulse waves, and so is a 
measure of the "minimal or diastolic pressure" 
within the artery. This figure is also read on the 
indicator and noted alongside that for the systolic 
50 "NORMAL" BLOOD PRESSURE 
pressure. The difference between the maximal 
systolic pressure and the minimal diastolic pres- 
sure is called the "pulse pressure." 
An enormous amount of research has been car- 
ried out to determine the average figures for 
maximal systolic and minimal diastolic pressures 
in healthy human beings. Wiggers2 sums it up 
well when he concludes that, in adult life up to 
middle age, the systolic pressure ranges from about 
110 to about 135 (millimeters of mercury); and 
the diastolic from about 70 to about 100 (with a 
usual range of from 70 to 90). After middle life, 
the systolic figure is usually a little higher, per- 
haps by 10 mm., though the diastolic changes but 
little in health. In children, the pressures are lower 
than in adults. The pulse pressure (systolic minus 
diastolic) is thus usually about 35 to 50 mm. of 
mercury in adults. 
Woley gives the following figures based on the 
examination of 1,000 healthy individuals: 
Age.. 
Average systolic pressure... 
15-30 
122 
31-40 
127 
41-50 
130 
51-60 
132 
2 Wiggers (C. J.). Modern Aspects of the Circulation in Health 
and Disease, Philadelphia, Lea & Febiger, 1923. 
51 BLOOD PRESSURE 
Fisher, working with life insurance statistics, re- 
ports slightly higher figures. 
Practically, then, the answer to the oft-posed 
question of what "normal" blood pressure is should 
perhaps be that there is no "normal," but that per- 
sistent systolic pressures below 110 (hypotension) 
and above 135 (after middle life, above 145) 
(hypertension) are to be looked upon with sus- 
picion. Similarly, persistent diastolic pressures 
below 70 (hypotonus) and above 100 (hypertonus) 
should be investigated. 
The diastolic pressure, it will be remembered, 
represents the amount of "squeeze" exerted by the 
arterioles upon the volume of blood in the arteries. 
Although, in health, it is constantly varying in dif- 
ferent parts of the body, an increase in one part is 
usually compensated for by a decrease in another, 
so that the sum total is kept fairly constant, despite 
the fact that the blood stream is deflected now to 
this organ and now to that. The diastolic pressure, 
as estimated by the sphygmomanometer, con- 
sequently varies only a few points measured either 
by day or by night. The systolic pressure, on the 
other hand, depends largely upon the activity of the 
52 "NORMAL" BLOOD PRESSURE 
heart, which may vary a great deal in response to 
physiologic needs. It is common knowledge that 
the pulse rate changes easily with changing physi- 
cal or mental states. We are not surprised, there- 
fore, to find that the systolic pressure shows greater 
fluctuations than the diastolic during the daily 
twenty-four hours. It is true, however, that both 
systolic and diastolic pressures usually rise and 
fall together, though not to the same extent. It may 
be said, with rough approximation to the truth, that 
the diastolic pressure is a fair measure of the con- 
dition of peripheral resistance in the arteries and 
arterioles (narrowing the caliber due to tonic con- 
traction or to organic narrowing) and that the sys- 
tolic pressure is a fair measure of the work of the 
heart over and above the resistance offered in the 
peripheral vessels. In any estimation of condi- 
tions obtaining in the circulatory system, it is most 
important, therefore, to be in possession of knowl- 
edge of both the systolic and the diastolic pressure; 
indeed, some excellent medical men attach more im- 
portance to the diastolic figure than to the systolic, 
believing rightly that it reflects the state of the ar- 
teries better than the systolic pressure possibly can. CHAPTER V 
INFLUENCES AFFECTING BLOOD PRESSURE IN 
HEALTH 
It may be that enough has been said to make 
clear several facts: (1) that blood pressure far 
from being an abnormal thing is essential to the 
circulation; (2) that it is, therefore, normally pres- 
ent in every living human being; and (3) that there 
is no such thing as a single "normal" level of blood 
pressure, but rather a normal range of blood pres- 
sure levels within which fluctuations may be ex- 
pected. The blood pressure is essentially an 
adaptive mechanism; and this point must be 
thoroughly grasped if we are to understand at all 
well the changes in blood pressure that accompany 
various diseased conditions. In fact, the only sane 
way to approach the entire subject of the blood 
pressure is through the realization that the changes 
of pressure occur in answer to demands of one kind 
or another made by the body upon the circulation. 
54 INFLUENCES AFFECTING BLOOD PRESSURE 
Increased blood pressure, even when marked, is not 
to be looked upon, in the last analysis, as bad in 
itself, but only as a circulatory condition brought 
about in answer to some abnormal condition existing 
elsewhere in the body. True it is that high blood 
pressure, if prolonged, will give rise, in its turn, 
to disturbances of other bodily functions, as we 
shall have occasion to see later; but at the begin- 
ning of its rise above the healthy average for the 
age and sex it is the expression of trouble some- 
where else rather than the cause of such trouble. 
If we should begin, here, to comprehend the prin- 
ciples that underlie the treatment of patients ex- 
hibiting high blood pressure, we must first make 
sure that we think of blood pressure in health as a 
beneficent phenomenon, as fluctuating within fairly 
well-defined limits, and as serving to adapt the flow 
of blood to the bodily needs. Since the body is 
never completely at rest (for even in sleep many 
of its organs must keep at work), and since it is 
now one organ and now another that demands 
change in its blood supply, it is not hard to see how 
alert the mechanisms that govern the blood pressure 
must always be. Day and night, adaptations in 
55 BLOOD PRESSURE 
blood supply must be made, and made swiftly, if 
health is to be conserved. 
Perhaps the easiest way to visualize these swift 
and frequent changes in blood pressure is to follow 
an imaginary person, Mr. X, through a period of 
twenty-four hours. To bring him nearer to us, let 
him be one of our personal friends. Let us suppose 
that he is just going to sleep as we begin to observe 
him. In from one to two hours his sleep should 
be its deepest, and his maximal (systolic) blood 
pressure will fall perhaps as much as twenty points. 
From that time on until early morning, say at about 
5 A. M., it will rise again slowly, but not to its 
average level for waking hours. The minimal 
(diastolic) pressure will change but little. Both 
maximal and minimal pressures will probably fall 
slightly every time he draws a breath, and will rise 
again as he exhales. 
When he gets out of bed, thus changing from a 
recumbent to a standing position, the blood will 
tend to gravitate into his legs and into the huge 
capillary bed and large veins of his abdominal 
organs; if this were to occur to any marked extent, 
the larger arteries would be more or less drained 
56 INFLUENCES AFFECTING BLOOD PRESSURE 
of blood, and the pressure in them would fall. But 
an increase in arteriolar tone will prevent the out- 
flow and the depletion of the larger arteries, and, 
as a result of more active contraction of the 
arterioles, the blood pressure will even rise a few 
points. Sometimes, indeed, after long illnesses or 
in other weakened conditions, the vegetative nerv- 
ous system does not respond quickly enough, and 
at first a little too much blood is allowed to run 
away from the arteries; the brain, being, in this 
case, the organ farthest from the ground, feels the 
deprivation first, and registers it in the form of a 
dizzy sensation. 
Our imaginary friend next takes his "setting-up" 
exercises, and if he be a healthy young adult, he 
may go through with them very vigorously. The 
muscles will call loudly for an increased supply of 
blood; the heart will respond with a quickened beat, 
and so will raise the systolic blood pressure, since 
it will pump into the arterial reservoir an increased 
amount of blood per minute. Simultaneously, the 
arterioles and capillaries within the active muscles 
will dilate to allow more blood to reach and nourish 
the muscle fibers. The fall of arteriolar tone thus 
57 BLOOD PRESSURE 
occurring will tend to lower the general blood pres- 
sure; but in this case the decrease of arteriolar tone 
will probably be more or less localized within the 
muscles then actually in use, whereas there may 
even be an increase of arteriolar tone in other parts 
of the body in compensation, to the end that the 
increased general pressure may be maintained and 
a good flow of blood to the muscular masses so 
insured. When the morning "stint" has been fin- 
ished, the maximal blood pressure may have risen 
thirty or forty points or even more, and the minimal 
from ten to twenty points. If new and complicated 
exercises that demand close attention are tried, the 
rise will be greater-perhaps as much as sixty or 
seventy points for the maximal and as much as 
thirty or forty points for the minimal pressures. 
If, again, the movements have demanded a great 
deal of straining, with diaphragm set and mouth 
closed, the maximal pressure may have risen 
momentarily to levels that are rare even in 
diseased conditions. A maximal blood pressure of 
200 millimeters or over may be registered during 
such strain. The minimal pressure will rise, too, 
but never so far beyond its average level. 
58 INFLUENCES AFFECTING BLOOD PRESSURE 
Breathless, perhaps, X throws himself into an 
easy chair for a moment's rest. The pulse rate falls 
to normal in from two to three minutes, and the 
pressure figures come down to X's usual average 
though a little less quickly. 
When he has "regained his breath" and his pulse 
rate and blood pressure are again "normal," X 
takes his "shower." If this be of warm water, we 
shall find that the arterial tone undergoes increase, 
resulting in a small rise of the minimal pressure 
(only a few points), an increase of heart rate and, 
as is usual, a rise of the maximal pressure greater 
relatively than that of the minimal. When, towards 
the end of the shower, he turns on the cold water, 
the minimal pressure will probably remain some- 
what elevated, though the maximal pressure and the 
pulse rate will fall. 
While he is dressing, X may begin to think of the 
day's work in store for him. He will remember, 
perhaps, an especially perplexing problem that is 
to come up during the morning, on the solution of 
which important consequences hang. If he be 
worried over the outcome his maximal pressure will 
rise somewhat as a result of his emotional state. 
59 BLOOD PRESSURE 
Breakfast over, finding that he will be late for his 
first appointment, he hurries to the garage, jumps 
into his automobile, and starts off for the office at 
top speed. This anxious mental state will be re- 
flected in his blood pressure and particularly in 
the maximal systolic figure. At a cross street 
another motorist, clearly without the right of way, 
hurtles into him and tears off a fender. An alter- 
cation ensues, during which X becomes ever more 
angry. Again there will follow a rise of systolic 
(maximal) blood pressure, due largely to an in- 
crease of the force and the rate of the heart's con- 
tractions. 
Here we may pause for a moment to consider the 
interesting effects of strong emotions upon the blood 
pressure. Some investigators have held that certain 
emotions, pain and fear particularly, are depress- 
ing in themselves; but, as Darwin long ago pointed 
out, "a man or animal driven through terror to 
desperation is endowed with wonderful strength, 
and is notoriously dangerous in the highest degree." 
In animals and in primitive man the strong emo- 
tions were but preliminaries to quick and violent 
action. Fear even now means tendency to fight or 
60 INFLUENCES AFFECTING BLOOD PRESSURE 
flight, and anger means desire to punish or to slay. 
The prospective muscular activity will demand an 
increased flow of blood, and that will depend upon 
stronger and faster heart action and upon an in- 
creased maximal blood pressure. Even though 
modern man has learned to control himself during 
fear and may neither fight nor fly, the physiological 
preparation for fighting or flight remains and his 
blood pressure becomes accordingly elevated. 
After luncheon X has a chance, perhaps, to sit 
down for a few moments, or better still, to take a 
short nap. If so, as a result, his maximal blood 
pressure, which in addition to all the fluctuations 
noted, has been showing a slight but steady rise 
throughout the waking day, will now fall a little, 
perhaps as much as from ten to fifteen points. But 
when he again goes to his desk and plunges into the 
complex details of his "paper work," this mental 
activity will be reflected in a moderate rise of his 
maximal pressure. 
The peak of the gradual daily rise of blood pres- 
sure will be reached about five o'clock in the after- 
noon, when, as a rule, fatigue begins to set in. 
Fatigue always brings with it a decline in the blood 
61 BLOOD PRESSURE 
pressure, not in the maximal pressure only, but also 
in the minimal. X will obviously have become 
tired with his day's work by this time. Fortunately, 
it is now time to close the office and to go home 
with a good dinner in prospect. 
Now a crucial time of the day for him has been 
reached. We have neglected mealtime up to this 
point, in order to emphasize the effect of the largest 
meal of the day, for this is a most important in- 
fluence upon the blood pressure. Overloading the 
digestive tract is one of the great hygienic sins of 
the average American. What with soup, a heavy 
meat with thick gravy, several vegetables, a salad, 
a rich dessert, and a cup of strong black coffee 
(that prince of heart stimulants), our friend X 
may find himself at the end of the meal uncom- 
fortably full and disinclined to any activity, either 
of his body or of his mind. Perhaps he may even 
drop off to sleep over his evening paper. If he 
thinks of it, he will probably find that his heart is 
beating at a faster rate than usual and will, per- 
haps, feel a little difficulty in getting a full breath. 
He lays this to the full state of his stomach, and to 
some extent correctly; but more than fullness of the 
62 INFLUENCES AFFECTING BLOOD PRESSURE 
stomach is concerned. The stomach and the in- 
testines have, by this time, become busily engaged 
in reducing the food taken during the meal to a 
variety of substances suitable for absorption and 
transmission to the temporary storehouses of the 
body. The digestion of food is not by any means 
a simple process. Waves of contraction pass over 
the hollow digestive organs and urge the food 
material forward through the alimentary tract; the 
muscular work involved in this is not inconsider- 
able. Besides chemical activity within the body is 
now at its height; digestive fluids must be secreted 
by the glands from the blood and poured out in 
profusion into the gastro-intestinal canal; and the 
prepared food-fluids must be passed through the 
intestinal walls and carried away from them by 
the lacteals and by the blood stream. There is thus 
an intense and continuous demand for blood and 
more blood for the vessels that supply the whole 
digestive tract. To fill the demand the great arte- 
riolar and capillary bed of this tract, as we have 
seen, by far the largest single system of the sort in 
the body, must undergo dilatation in order to allow 
the passage of the unusual amounts of blood tem- 
63 BLOOD PRESSURE 
porarily required. We might expect that the blood 
pressure would be lowered as a result of this dilata- 
tion in the digestive domain; but, on the contrary, 
a rise ensues, for again compensatory changes in 
the arteriolar and capillary system occur elsewhere. 
The skin area, for instance, may be called upon for 
help, and we may find that as a consequence it 
misses the amount of heat that the usual volume of 
blood brings to it, and registers the lack as a feel- 
ing of mild chilliness, especially if the temperature 
surrounding the body be at all low. An even more 
potent factor in maintaining the blood pressure 
above normal during digestion, however, is the 
more rapid and more forceful action of the heart. 
The preponderance of the increased heart action 
over the dilatation of the capillaries in the splanch- 
nic, or digestive, area is evidenced by the rise in 
maximal blood pressure. The minimal is little 
changed. The effect of active digestion on the heart 
is, then, much the same as that of muscular exercise. 
Later in the evening, Mr. X goes to bed and to 
sleep; after an hour or two his blood pressure will 
be somewhere near the level of that obtained twenty- 
four hours earlier. 
64 INFLUENCES AFFECTING BLOOD PRESSURE 
If Mrs. X be thought of as being of the same 
age and as healthy as her husband, her pressure 
will tend to be maintained at levels from five to 
eight mm. of mercury below his. If the two weigh 
more than they should, and especially if they be 
very fat, their pressure may be considerably above 
the average figure; and the heavier they are, the 
higher their pressure. If, instead of being Ameri- 
cans, they should be natives of the Far East, their 
average pressures would be 10 to 30 mm. lower 
than their western fellows; although if they should 
then emigrate to America, it would be found, after 
a time, that their pressures had risen some five 
points or more. Again, at times, when the baro- 
metric pressure is high, the blood pressure rises 
slightly, other influences being equal and with a 
falling barometer the blood pressure also tends to 
fall a little. If they should ascend Pike's Peak, by 
railway (to eliminate the factor of muscular work), 
both maximal and minimal pressures would be 
found slightly lower at the summit than in the 
valley below; though after a few days of residence 
at the top both pressures would return to about 
average levels. 
65 BLOOD PRESSURE 
If we could follow the blood pressure of either 
of our friends through life, we should of course 
find great differences in the pressure levels at vari- 
ous ages. Thus, according to the results of one 
series of investigations, in which some 2,300 obser- 
vations were made, the blood pressure averaged 
91.8/65.6 mm. of mercury (the numerator being 
the maximal, and the denominator the minimal 
figure) at 3 years, and 105.6/67.5 at 15 years.1 
And another series of investigations, in which the 
blood pressure levels in relation to body weight 
were recorded, yielded the following results:2 
Weight Systolic blood pressure 
Infancy 75-90 mm. of mercury 
30- 40 lbs 95 
40- 50 lbs 100 
50- 60 lbs 107 
60- 70 lbs 112 
70- 80 lbs 116 
80- 90 lbs 122 
90-100 lbs 126 
Thus it will have been made plain that every 
day, and throughout every day, the blood pressure, 
1 Judson & Nicholson. Am. J. Dis. Child., 1914, viii, 257. 
2 Michael. Am. J. Dis. Child., 1911, i, 272. 
66 INFLUENCES AFFECTING BLOOD PRESSURE 
both maximal and minimal, is fluctuating in obedi- 
ence to physiological laws and in answer to vary- 
ing physiological demands; and that, therefore, 
no single level dare, dogmatically, to be called 
"normal." In a young, healthy individual, it will 
be found that the range of pressures during a single 
day may be from 110 to 170 (or even to 200 or 
more, under stress of violent exertion) for the 
maximal figure, and from 70 to 80 (or 85) for 
the minimal figure. This entire range is to be 
looked upon as "normal," when the various activi- 
ties are considered. The "average" for the waking, 
resting periods might be about 125/70. This is 
the best answer we can honestly make to the ques- 
tion "What is 'normal' blood pressure?" CHAPTER VI 
ON SOME VARIETIES OF HIGH BLOOD PRESSURE 
AND THEIR CAUSES; RELATIONS TO 
HARDENING OF THE ARTERIES 
High blood pressure is often spoken of as ar- 
terial hypertension. The high figures that were 
referred to in the previous chapter as occurring 
occasionally as normal results of physiological 
processes do not merit the name of pathological 
hypertension: first, because they are produced by 
normal mechanisms; and secondly, because they are 
merely temporary and not persistent. Hyperten- 
sion as a pathological term applies to those high 
blood pressures that are the result of abnormal 
processes within the body and which are also more 
or less chronic or permanent. The term "hyper- 
tension" has, furthermore, been more expressly 
applied to a heightened maximum (or systolic) 
pressure, for the reason that this maximum pres- 
sure suffers greater deviation from the average 
than does the minimum (or diastolic). When the 
minimum pressure remains at a level higher than 
68 VARIETIES OF HIGH BLOOD PRESSURE 
the average, the condition is sometimes spoken of 
as "hypertonus," signifying that the fundamental 
tone of the arterioles is increased beyond the degree 
existent in health. It would seem best in a book 
like the present one to woo simplicity; "hyper- 
tension" will, therefore, here be understood to mean 
an abnormal and more or less permanent increase 
of maximum systolic, of minimum diastolic pres- 
sure, or of both. 
The causes of hypertension are sometimes de- 
scribed as being either "functional" or "organic." 
These are rough-and-ready terms that have a certain 
practical value, though from the theoretical stand- 
point they offer great difficulties to exact definition. 
All through the realm of medicine a phenomenon 
is ordinarily spoken of as being of functional origin 
when it depends upon a temporary unbalancing of 
the physiological processes of the body. Thus, a 
green-apple stomach-ache is regarded as a "func- 
tional" disorder. There is no doubt that "ab- 
normal" symptoms are present-that something is 
wrong. The trouble is not due to any gross change 
in the structure of the stomach, however, but rather 
to the way it works under an unusual stimulus. The 
69 BLOOD PRESSURE 
unripe fruit has induced an "upset" of the ordinary 
mechanisms of digestion, as a result of which the 
stomach can not carry on its usual work. Under 
dissection and examination by the microscope, 
nothing, perhaps, could be found structurally wrong 
with the stomach. The trouble is, accordingly, 
spoken of as functional; in the absence of "struc- 
tural" change, the function can usually be brought 
back to its normal. In the case of disturbance due 
to the eating of green apples, nature adequately 
meets the situation; the offending contents of the 
stomach are removed, the gastric function returns 
to normal, and the episode is over. 
But if pain and vomiting are due to some altera- 
tion of the stomach's structure, such, for instance, 
as an ulcer, then the case is quite different. Disturb- 
ances dependent upon such gross structural changes 
are described as being definitely "organic." Func- 
tion suffers, of course, but the cause of the func- 
tional disturbance lies in an obvious and relatively 
gross change in the stomach machinery. This is a 
more serious matter for, even though the lesion 
may be healed by appropriate methods, a scar is 
likely to result, and the organic change will have 
70 VARIETIES OF HIGH BLOOD PRESSURE 
left its permanent mark. We can scarcely hope as 
physicians to see that stomach return to the same 
perfect state in which it was before the ulcer de- 
veloped. 
As a matter of fact, it is probable that there are 
no functional manifestations without some simul- 
taneous structural changes. But in the functional 
disorders (so-called) as contrasted with the organic 
disorders (so-called) the changes are minute-of 
a physical or chemical order, rather than of an 
anatomical order of grossness. 
The same considerations hold true for arterial 
hypertension. Some cases are called functional; 
and in them the blood pressure will return to 
average levels if the causes of dysfunction are re- 
moved. Other cases are called organic; they are 
due to some structural change in the heart, in the 
blood vessels or in other organs; and in these cases, 
though the process may be prevented from grow- 
ing worse, it can seldom be got rid of entirely, nor, 
as a rule, can the patient hope to see his blood 
pressure return to its earlier levels and remain 
there. 
When we thus separate these two classes of 
71 BLOOD PRESSURE 
causes of hypertension-the functional and the 
organic-we do not mean to form two entirely 
separate and mutually exclusive groups. On the 
contrary, as is so often the case in science when we 
attempt to classify delicate and mutually inter- 
dependent processes, these classes tend to run into 
one another. Though there are certain cases of 
hypertension that none would hesitate to set down 
definitely as functional, and certain others that 
would just as readily be designated organic, there 
are still more cases that are intermediate and par- 
take of the nature of both the extreme classes, 
being partly functional and partly organic, or in 
the process of passing over from the functional 
class to the organic. It is very probable that func- 
tional hypertension should be looked upon as a 
symptom of the early stages of processes that may 
lead subsequently to organic forms of hypertension. 
With this preliminary warning that the classifica- 
tion of the chronic arterial hypertensions into func- 
tional and organic presents especial difficulties, 
we may pass on to an examination of the circum- 
stances in which they are found to occur. 
The functional hypertensions appear to arise in 
72 VARIETIES OF HIGH BLOOD PRESSURE 
association with certain persistent mental states or 
with intoxications in which some known or un- 
known poisonous substances circulate in the blood. 
The commonest of the causes to which high blood 
pressure has been attributed is the abnormal "wear 
and tear" of our modern life. We are proud of 
our traditional American "pep," and of the ability 
of the American "to get things done." If we can 
"go the other fellow one better," we do not stop 
to count the cost to us in the tense, driving hurly- 
burly of our days nor in the anxiety of our sleep- 
less nights due to taking our worries home with us 
and to bed. The American business man is prone 
to think that he must not yield to relaxation if he 
is to "win out." There can be no intermission in 
his game. He will reach Athens, even if he die 
with the cry of "Victory" on his lips! 
Though this new-world attitude has its excel- 
lences and is responsible for much of America's 
commercial greatness, it can be, and only too often 
is, practiced to an extreme. And it is a vast and 
hideous mistake when it is allowed to injure seri- 
ously the country's business and professional per- 
sonnel. This result might have been anticipated 
73 BLOOD PRESSURE 
and it is, in fact, becoming increasingly evident in 
American life. For tenseness, anxiety, and fear 
are bad habits of mind-habits that sooner or later 
are inimical to the welfare of the body. Anxiety 
and worry involve an element of fear, and, as we 
have seen in a former chapter, fear and emotions 
allied to it condition unconscious preparations for 
either fight or flight, which in turn are accompanied 
by a rise of blood pressure in order to prepare the 
circulatory system for the expected strenuous work. 
Even though the necessity for violent muscular 
action should not be arrived at, the preparation for 
it remains the same. If normal intense mental con- 
centration is accompanied by a normal rise of blood 
pressure, which falls again to average levels when 
the mental work is over, it is easy to see how ab- 
normal mental perturbation, persisted in all day 
long and every day, might establish after a while 
a blood pressure that also is abnormal not alone in 
its degree, but also in its persistency. And this is 
precisely the result that is observed. The man of 
many affairs, who provides himself with no time 
for rest and relaxation, because he may feel and 
believe himself to be at the top notch of physical 
74 VARIETIES OF HIGH BLOOD PRESSURE 
perfection, would do well to bear in mind the subtle 
changes that may be going on within him. His 
wife, perhaps equally busy and beset by all manner 
of social and household worries, may be in similar 
case. It is pleasing to see the return to normal or 
to nearly normal, so far as blood pressure goes, of 
such persons as are sane enough to take a physi- 
cian's advice when he recognizes their faults of 
hygiene and prescribes rest and moderation in 
activities or even complete withdrawal from affairs 
for a time. 
Some of the instances of high blood pressure 
without organic changes unhappily do not seem to 
depend upon psychic factors only. In them, the 
functional hypertension may increase without ap- 
parent cause, year by year, despite treatment. 
Much has been written about this type of hyper- 
tension. One great Englishman has thought the 
group of cases sufficiently distinct to warrant their 
inclusion under the special name, "hyperpiesis." 
The process is usually assumed to depend upon the 
presence of a noxious substance, elaborated some- 
where in the body, which circulates in the blood and 
stimulates the arterioles to contraction, either by 
75 BLOOD PRESSURE 
acting upon the vasomotor center in the brain or 
by acting directly upon the arteriolar musculature. 
As a result of the increased resistance to outflow 
through the arterioles, there is a rise of the mini- 
mum pressure. To overcome this increased resist- 
ance to outflow from the arterial system, and so to 
maintain the integrity of the circulation as a whole 
the heart must do a larger amount of work. And 
as we have seen, increase of the heart's effort, 
whether this consist of a more frequent rate of con- 
traction or of an increased force of individual 
beats, leads to a rise of the maximum pressure. 
Thus both minimal and maximal pressures reach 
higher levels. 
Again, hypertension, in the sense of an increase 
of blood pressure that is not in response to any 
normal stimulus, may follow the use of certain 
drugs. Caffeine, in coffee, certainly raises the pres- 
sure temporarily; so does the nicotine in tobacco; 
but it has not been proven that even the long-re- 
peated use of these poisons results in more than 
temporary rises of the blood pressure. Alcohol, 
also, has been incriminated as a cause of high blood 
pressure; but here again, the proof is lacking. 
76 VARIETIES OF HIGH BLOOD PRESSURE 
Though men or women who have used alcohol to 
excess frenquently exhibit hypertension, it is quite 
possible that the changes that underlie it may have 
been brought about by concomitant faulty habits of 
hygiene quite as much as by any direct action of the 
alcohol. Adrenalin, secreted normally by one of 
the glands of internal secretion, is a powerful 
hypertensive agent; but its action is short-lived. 
The theory that hyperpiesis is due to a continuous 
over-secretion of this substance has not been upheld 
by experiment. Workers in lead, mercury, and 
zinc often develop high blood pressure, due, how- 
ever, to organic changes in the arteries and kidneys 
induced by the long-continued action of these 
poisonous metals. 
Women sometimes show a functional hyperten- 
sion just before the menstrual periods and often 
also when the "change of life" is beginning. Here 
the functions of the glands of internal secretion are 
almost certainly involved, but the precise relation- 
ship and the mechanisms of their action are not yet 
known. It should be added that the internal secre- 
tions may have something to do with hyperpiesis 
in men as well as in women, and also that they may 
77 BLOOD PRESSURE 
affect the blood pressure in women at times other 
than those of menstrual disturbances. 
It is fascinating to speculate upon what part 
heredity plays in these functional hypertensions. 
Someone has said that "man is physically as well 
as metaphysically a thing of shreds and patches 
borrowed unequally from good and bad ancestors, 
and is, therefore, a misfit from the start." Cer- 
tainly, some persons are more able than others to 
stand great and long-continued strains without 
showing signs of wear and tear; and there is good 
reason to believe that some of us possess arteries 
that are endowed with a better quality of tubing 
than do others. Individual nervous make-up is 
pertinent, too. The arterial system responds readily, 
as we have seen, to nervous influences, and every- 
one knows that there are great individual differ- 
ences in nervous excitability for which heredity 
may be in large part responsible. 
So much for the groups of hypertension that are 
not associated with any demonstrable organic 
change anywhere in the body. These groups stand 
at one end of the whole series of hypertensive dis- 
orders. The middle group is confused, as we have 
78 VARIETIES OF HIGH BLOOD PRESSURE 
said above, so that it will be best to skip it and to 
turn at once to an examination of well-defined cases 
at the other end of the series, where we find hyper- 
tension definitely associated with recognizable 
structural (that is to say, organic) changes in vari- 
ous parts of the body. 
The most important of these changes are found 
in the walls of the blood vessels themselves. Under 
certain conditions, to be mentioned later, a real 
alteration occurs in the structure of the walls of the 
arteries. The elastic elements disappear to a con- 
siderable extent and are supplanted by fibers of 
white fibrous tissue, a tough, strong, unyielding 
material that serves everywhere throughout the 
body as a binding element, and of which tendons, 
ligaments, and scars are largely formed. To- 
gether with this fibrous change in the walls of the 
arteries a thickening of the walls occurs which, 
actually narrowing the caliber of the vessel, en- 
croaches upon the space for blood. An artery that 
has undergone fibrous change and thickening is 
deprived of much of its elasticity, a quality that we 
have seen to be indispensable to proper function- 
ing. In addition, more or less calcium, the presence 
79 BLOOD PRESSURE 
of which in bone is responsible for its hardness, may 
be deposited in the already thickened walls of the 
arteries. The end-result of all these changes that 
may take place in the walls of the larger arteries is 
serious injury to the flexible, elastic artery, which, 
in health, accommodates itself so easily to varying 
pressures during each cardiac cycle, which tends to 
lessen the height of the systolic pressure, and which 
changes the vigorous spurt of the blood as it is 
received from the heart to a steady onflow as it is 
delivered to the arterioles and capillaries;-the 
artery of normal type is converted into one with 
stiff, unyielding walls, which cannot receive elasti- 
cally the vigorous thrust of blood at each heart beat 
nor modify the pulse wave into a steady onflow. 
Such a diseased vessel has much in common with 
a rigid metallic tube. In the larger artery thus 
damaged the maximal pressure may remain much 
the same as the pressure exerted within the chamber 
of the heart, since none of the energy is absorbed 
and rendered temporarily latent through the media- 
tion of an elastic vessel wall; and since the normal 
elastic recoil of the wall of the healthy large artery 
behind the pulse wave with its continuing squeeze 
80 VARIETIES OF HIGH BLOOD PRESSURE 
upon the contained blood is absent, the minimal 
pressure will, other things being equal, tend to fall 
below the average normal figure. The difference 
between maximal and minimal blood pressure is 
called, as we have seen, the "pulse pressure," and 
it will be recalled that it is a measure not only of a 
large part of the work which the heart is called upon 
to accomplish with every beat, but also of the strain 
to which the vessel walls are subjected with the 
passage of each pulse wave. 
In arteriosclerosis of the larger arteries, there- 
fore, the maximal (systolic) blood pressure will 
tend to be raised, the minimal (diastolic) pressure 
to be lowered, and the pulse pressure to be in- 
creased. Normal arteries, in which the elastic 
quality is unimpaired, can easily withstand, at least 
for short periods of time, a marked increase of 
pulse pressure; but with a gradual increase of the 
rigidity of the arterial walls there develops an in- 
creasing inability to expand elastically to the pass- 
ing pulse wave, until at last, under the continued 
hammering of the systolic pressure, the walls begin 
to "give way." Then ensues either a dilatation of 
the vessel, seen oftenest (by X-ray) in the aorta just 
81 BLOOD PRESSURE 
after it leaves the heart, or an actual lengthening, 
with tortuosity, plainly to be seen by the eye in the 
arteries of the temple. The actual hardening of 
the walls of the arteries of medium size can be 
appreciated by the finger in various parts of the 
body. 
Not always do the arteriosclerotic changes pro- 
gress to this point, however, nor do they occur 
equally distributed throughout the various arteries 
of the body. The arteries supplying the limbs and 
the head may, in some cases, be predominantly 
affected while the smaller arteries and arterioles 
hidden in the internal organs may escape; and, in 
other cases, the arteries of the vital organs may be 
badly sclerosed without any evidence of the process 
appearing in vessels accessible to sight or touch. 
Moreover, arteriosclerosis may affect the arteries 
of one region while it spares those of another. Thus 
evidences may be present of arteriosclerosis of the 
vessels of the brain alone, or of the kidneys alone, 
or of those small vessels that nourish the muscle- 
tissue of the heart wall, or of the peripheral vessels 
only. It is certainly quite common, however, to 
find the arteriosclerotic process very widespread. 
82 VARIETIES OF HIGH BLOOD PRESSURE 
The change from normal to sclerosed blood ves- 
sels is, of course, gradual, and the beginning of the 
change is insidious, and without symptoms. And 
in this insidious beginning and gradual develop- 
ment lies the great danger to the possessor of the 
vessels. As a rule he is not aware of the process 
until it has become well established and until 
symptoms have begun to make their appearance. 
Moreover, the symptoms vary with the variable 
location of the process in its greatest intensity. 
Since in this volume we are most concerned with 
blood pressure, it may be pointed out that sclerosis 
of the smaller arteries and arterioles has a greater 
effect upon that pressure than has hardening of the 
larger arteries. The reason for this will be clear, 
when the compensatory effects of the tone of the 
smaller vessels are remembered. Thus, with a 
tendency to higher pressure through stiffening of 
the walls of the larger arteries, a compensatory 
dilatation of the arteriolar system may be sufficient 
to hold the resultant blood pressure down to its 
usual levels. When the site of the sclerotic process 
is in the smaller arterioles themselves, however, 
there is impairment of such compensatory function. 
83 BLOOD PRESSURE 
Since sclerosis of the smaller vessels results almost 
uniformly in narrowing of their caliber, the effect 
upon the minimal pressure is the same as that of 
heightened vascular tone from muscular contraction 
of the vessel walls, except that it is permanent and 
due, not to normal physiological adjustments, but 
to abnormal structural changes. Abnormal resist- 
ance to the outflow of the blood from the system 
of larger arteries is thus created (increased mini- 
mal blood pressure), which the heart must over- 
come by more forceful beating (causing increased 
maximal blood pressure). The maximal pressure 
rises proportionately higher than the minimal, as 
is the rule, so that the pulse pressure is increased. 
A greater pulse pressure means a greater strain 
upon the already damaged vessel walls, with 
stretching and the formation of still more dense 
tissue. This, in turn, leads to still further narrow- 
ing of the caliber of the vessels, completing a 
vicious circle. When we see a high diastolic pres- 
sure without a pulse pressure that is higher than 
normal, we suspect some weakness of the muscle 
of the heart that prevents the maintenance of the 
systolic pressure at a high level. 
84 VARIETIES OF HIGH BLOOD PRESSURE 
Thus far, in speaking of arteriosclerosis, changes 
in the circulatory system only have been considered. 
It is to be recalled, however, that the function of 
the circulatory system is to furnish blood to all the 
organs of the body and to drain these organs of 
blood; not only do blood vessels (arteries) carry 
food and oxygen to the organs, but blood vessels 
(veins) also take away from them the waste prod- 
ucts that result from their activities. The health 
of each individual organ, as well as the health of 
the body as a whole, is dependent upon an adequate 
supply of blood. If, then, the supply of blood to 
an organ is impeded by narrowed arteries, or if, 
through loss of the normal pliability of the vessel 
walls, the supply can not be gauged to the chang- 
ing needs of that organ, then its functions must 
suffer. Eventually the very structure of the organ 
will be affected by reason of faulty nutrition; for 
an interesting fact regarding the living human body 
is that wherever an organ, a gland, or a cell func- 
tions less, it grows smaller. Thus the unused 
muscles of the East India holy men become reduced 
to little more than mere strands of fibrous tissue; 
85 BLOOD PRESSURE 
the unused eye of a "cross-eyed" person loses the 
function of vision. 
Now sclerosis of the small blood vessels (arteri- 
oles) within the vital organs leads to more or less 
marked structural changes in those organs, changes 
that involve the ability of the organs properly to 
function. If this occurs in the kidneys, there is a 
slow impairment of kidney function; if in the brain, 
mental changes may become manifest, or a para- 
lytic stroke may occur; if in the wall of the heart 
itself, attacks of angina pectoris or of other heart 
disorders may be experienced; and so on. 
Of the causes of arteriosclerosis much has been 
written and but little is actually known. Certain it 
is that heredity must play a large part here, as it 
apparently does in the origin of so-called essential 
hypertension (hyperpiesis; hypertension without 
demonstrable organic changes). Indeed it is prob- 
able that hereditary disposition is the predominant 
factor. It is not at all unusual to find a history of 
attacks of apoplexy running through a family; if it 
be objected that the "stroke" was a complication of 
kidney disease (and thus presumably not directly 
due to vascular disease in the brain), it can often 
86 VARIETIES OF HIGH BLOOD PRESSURE 
be shown that the kidney disease was caused by 
sclerosis of the arterioles of that organ, that hyper- 
tension was associated with the kidney disease, and 
that, finally, a vessel in the brain, sclerosed just as 
were those in the kidney, gave way to the increased 
blood pressure. Still other evidences of familial 
arteriosclerosis might be adduced. 
The acute infections of youth may be responsible 
for the development of more cases of arterial hard- 
ening in after life than we have been accustomed to 
believe. Recurring tonsillitis and other infections 
due to streptococci may be of importance. Thayer 
has called attention especially to the possible rela- 
tion of typhoid fever in the earlier years of life to 
subsequent changes in the walls of the arteries. 
Indeed, when it is remembered how often the toxic 
substances elaborated in the course of scarlet fever 
attack the kidneys and leave them impaired, and 
how frequently the diphtheria toxin causes (or, 
rather, did cause, before the blessed advent of anti- 
toxin) severe paralyses due to injury of the nerve 
fibers, it is not hard to believe that other structures 
in the body, especially the blood vessels, may be 
harmed by these and similar poisons, and that the 
87 BLOOD PRESSURE 
vessel walls, exposed as they are constantly to the 
severe stresses of the circulatory cycle, sooner or 
later show degenerative changes. 
The poisons retained in the system and circulat- 
ing in the blood as a result of impaired function of 
the kidneys are a potent source of damage to the 
arterial walls. Even though frank arteriosclerosis 
may not result at once from the poisoning, it is 
believed that these poisons carried through the 
blood may affect the vasomotor center in the brain 
and give rise to an increased blood pressure through 
resulting constriction of the walls of the arterioles. 
Besides the deleterious effects of the poisons 
produced in the course of the acute infectious 
diseases and of the poisons that are retained in the 
system when there is faulty elimination by the 
kidneys, certain poisons absorbed from the outer 
world may exert a damaging influence upon the 
arterial walls and lead subsequently to their 
thickening. Workers in lead and in mercury, es- 
pecially, suffer such damage, a fact of the greatest 
importance for personal hygiene and for the hy- 
giene of industries. 
In advancing age retrograde changes of various 
88 VARIETIES OF HIGH BLOOD PRESSURE 
sorts occur throughout the body. The arteries do 
not escape, and we find arteriosclerosis occurring in 
ever greater degree as the years of a person in- 
crease. In the absence of the poisonings above 
referred to, the age at which thickened vessels be- 
come noticeable and the rapidity with which the 
process of arteriosclerosis advances in a given per- 
son are, in a way, a measure of that person's in- 
herited disposition in this one particular. Arteri- 
osclerosis though very rare in infants is not wholly 
unknown in them; on the other hand, we see some 
persons in even advanced old age who show but 
few or no signs of it. The old saying that "a man 
is as old as his arteries" has some truth in it as far 
as it bears upon the "expectation of life"; but 
there are such great individual differences to be 
met with in arterial conditions that any attempt to 
guess, on information derived from them, of the 
actual number of years a person has lived, would 
be little less than foolhardy. 
Certain metabolic diseases, notably diabetes 
mellitus and gout, also predispose to arterio- 
sclerosis and may be accompanied by high blood 
pressures. In these diseases an excess of certain 
89 BLOOD PRESSURE 
substances (sugar in diabetes; uric acid in gout) 
can constantly be demonstrated in the blood. Tuber- 
culosis is sometimes a cause of arteriosclerosis of 
the larger vessels, but it is rare to find tuberculosis 
associated with high blood pressures; in most cases 
of this malady abnormally low blood pressures are 
encountered. An infection with syphilis is held by 
certain writers to predispose the patient to the 
development of arteriosclerosis. 
Caffeine, nicotine, and alcohol have been ac- 
cused as potent causes of arteriosclerosis, but recent 
researches do not seem to support the accusation so 
far as moderate use is concerned. 
Excessive mental or physical work, and indeed 
excesses of all kinds, do seem to have a real causal 
effect in the production of disease of the arteries. 
Particularly is this true of over-eating. The heavy 
eater may also be physically inactive; gluttons are 
notoriously negligent of proper bodily exercise. 
Obesity after middle life is very often associated 
with high blood pressure and some arteriosclerosis. 
Stuffing of the stomach puts a great load on the 
digestive system, and this in turn interferes with 
normal circulation and respiration precisely at a 
90 VARIETIES OF HIGH BLOOD PRESSURE 
time when the digestive system is demanding an 
increased supply of blood for its complicated work. 
As we have seen, the blood pressure is normally 
always higher just after a heavy meal. If the 
strain on the circulatory system caused by diges- 
tion be increased by overloading the stomach, and 
especially if the strain be habitually repeated, there 
will almost surely come a time when damage will 
be done to the arteries and "hardening" will 
gradually ensue. Moreover, very often the heavy 
eater is simultaneously an immoderate drinker of 
alcohol, an inordinate smoker of tobacco and per- 
haps inclined to excesses in still other directions. 
He who wishes to live so as to protect his arteries 
from damage, will avoid over-abstemiousness on 
the one hand and over-indulgence on the other; 
"safety lies in a middle course." 
The possible causes of arteriosclerosis are, as 
we have seen, many; and some of them are coarse, 
others subtle and their mode of action obscure. In 
all fairness, it must be added that sometimes on 
studying a person manifesting arteriosclerosis, no 
definite cause can be found, and it is necessary to 
conclude that the person has been unfortunate in 
91 BLOOD PRESSURE 
the original quality of his "tubing"; that is to say, 
that through his inheritance he has come to be the 
possessor of arteries of an inferior grade. 
We have thus far in this chapter discussed the 
forms of hypertension that lie at the two ends of a 
series; we have spoken (1) of those forms of hyper- 
tension that are not associated with any demon- 
strable organic change in the body, and (2) of 
those forms that are definitely associated with such 
changes. But in so complex an organism as the 
human body, abnormal function of any kind seldom 
exists long without becoming associated with at 
least some corollary organic effects. We cannot 
expect, for instance, to find many cases of simple 
hypertension, especially if it persist for any length 
of time, without being able to discover sooner or 
later that it has become associated with organic 
changes here or there in the body. The members 
of this end of the series of hypertension cases merge 
insensibly into the members of the other end of 
the series through the members in a great middle 
area; the progression is naturally from the simple 
hypertensions to those associated with organic 
changes. Indeed, by some authors simple or essen- 
92 VARIETIES OF HIGH BLOOD PRESSURE 
tial hypertension, or hyperpiesis (to give it all the 
names we have mentioned in this chapter) is con- 
sidered but the preliminary stage of a malady that 
will later further reveal itself in arteriosclerotic 
processes in the large peripheral arteries and in 
the arterioles of the vital organs. To these writers 
the sequence is clear from simple excessive blood 
pressure to arteriosclerosis and so to all the 
maladies of kidney, brain, and heart that mark the 
end of so many elderly persons' lives. There are 
some writers who believe that the first change is a 
subtle degeneration of the walls of the smaller 
arteries and arterioles, with a consequent rise of 
blood pressure, and that after this a vicious circle 
is established, the rise in blood pressure leading to 
further degeneration of the arteries. 
Whatever the sequence, permanent increase of 
blood pressure and degeneration of the arterial 
and arteriolar walls seem to be complementary 
processes; together they lead gradually to the im- 
pairment of various vital functions. A brief survey 
of the functions that are thus impaired, with great 
danger to the health and even to the life of the 
individual, must be reserved for another chapter. CHAPTER VII 
THE HEART, THE KIDNEYS, AND THE BRAIN IN 
PATIENTS MANIFESTING HIGH BLOOD 
PRESSURE 
Both the functional and the organic types of 
hypertension become associated, sooner or later, 
with structural alterations in various organs of the 
body-insidious changes, which impair the health 
and which will eventually, if unchecked, terminate 
life. Some of these changes have been hinted at 
in previous chapters, but it will be well now to 
look a little more closely at the more important 
of them. In considering the concomitants of high 
blood pressure, we shall pay attention particularly 
to the changes that may occur in the heart, the 
kidneys, and the brain, for these are vital organs 
that must function perfectly if health is to be 
conserved. Moreover, these are the organs that 
suffer oftenest in persons who manifest high blood 
pressure and (when long continued) its corollary, 
94 HEART, KIDNEYS AND BRAIN 
arteriosclerosis, with its attendant disturbances to 
the circulation. In the previous chapter we have 
seen how some of these changes may be brought 
about; now we must inquire into the special in- 
fluence of these changes upon the three organs 
spoken of, and at the same time we shall try to 
discern how the chains of morbid phenomena are 
forged. 
Though the story is not a pleasant one, it must 
be told if we are to arrive at an understanding 
of the mechanisms by which patients manifesting 
hypertension come to have their lives endangered. 
But the reader who chances to have a high blood 
pressure must be warned emphatically against the 
tendency to search within himself for all the com- 
plications of hypertensive troubles of which he now 
learns. The discovery and management of such 
complications is the task of the physician, not of 
the patient. For that very reason, no detailed list 
of symptoms referable to these complications is 
here written down. Too many non-medical read- 
ers might become introspective and develop un- 
necessarily states of anxiety from worrying about 
themselves and their future. It has already been 
95 BLOOD PRESSURE 
shown how baleful the effects of such mental states 
may be upon even "normal" blood pressures and it 
will, accordingly, be easy to understand why the 
hypertensive patient should be carefully shielded 
from all unnecessary worry. It can never be the 
purpose of any good physician to arouse fear in 
his patients. It is, rather, his duty to point out 
carefully to the patient, without unduly alarming 
him, the pitfalls that may lie before him and to 
teach him how to avoid them. Indeed, the purpose 
of this little book is to perform for its readers that 
very service in respect of arterial hypertension. 
Though the possible complications of that hyper- 
tension, as we have said, are not pleasant to dwell 
upon, they must be set forth in this chapter in order 
that the reader may better understand the neces- 
sity for his observance throughout life of those 
principles of good personal hygiene (inclusive of 
proper diet) which the science of preventive medi- 
cine has shown are most effective in postponing the 
advent and progress of the processes that underlie 
hypertension. In this spirit of sensible caution, 
then, and without fear, let us examine some of the 
possible complications of hypertension, particu- 
96 HEART, KIDNEYS AND BRAIN 
larly those that concern the heart, the kidneys, and 
the brain. 
If we take the simplest case, that of so-called 
"functional" or "essential" hypertension (or hyper- 
piesis) the exact cause of which, it will be recalled, 
is not yet fully known, it will be evident that in- 
creased blood pressure within the arteries means 
that extra work is required of the heart, since the 
maintenance of a satisfactory circulation when 
there is increased resistance to the outflow of blood 
from the heart at each beat will depend upon more 
forcible contractions of the walls of the heart. The 
muscle of the heart wall, like all other muscle 
tissue in the body, responds to increased work with 
an increase in size of the individual muscle fibers, 
and with a consequent increase of the whole muscle 
mass. No one should be surprised, therefore, to 
be told that some enlargement of the heart occurs 
in chronic arterial hypertension. This enlargement 
may be demonstrable within four weeks after the 
appearance of a permanently raised blood pres- 
sure; with time the enlargement may progress, in 
the course of years or decades, to an almost un- 
believable extent. Some of the largest hearts en- 
97 BLOOD PRESSURE 
countered in postmortem examinations by pathol- 
ogists are thus explained. But when the heart 
is called upon to perform over a long period an 
amount of work that is greater than that called 
for under normal conditions, changes other than 
that of mere hypertrophy (increase in size and 
strength) gradually occur. Eventually, say after 
several, often only after many years, the nutrition 
of the heart will begin to suffer; degeneration 
of the heart muscle fibers may set in, fibrosis of the 
walls of the heart may develop, and the muscula- 
ture of the heart will become unequal to its task. 
When the heart muscle thus begins to flag, the 
chambers of the heart will begin to dilate, the 
maximum systolic blood pressure, which is largely 
dependent upon the heart's action, will fall, though 
it may still remain well above the average level 
maintained in health. And since the minimum 
diastolic pressure is still maintained at an abnor- 
mally high level, owing to the contraction of the 
walls of the peripheral arterioles (the fundamental 
condition in essential hypertension), the fall of the 
maximum systolic blood pressure involves a fall 
in the pulse pressure, and this means, in turn, that 
98 HEART, KIDNEYS AND BRAIN 
the circulation of the blood in the body becomes 
insufficient. Then follow the signs and symptoms 
of "heart failure," a term that means, not the 
failure of the heart to beat at all, but its failure 
to beat powerfully enough to maintain an efficient 
circulation of the blood. 
It should be remembered, then, that essential 
hypertension may, sooner or later, lead to an 
inability of the heart to maintain a proper circu- 
lation of blood, one of the earliest symptoms of 
which is undue breathlessness upon exertion. Some- 
times the sequence of events is rapid, but more 
often the changes develop very slowly over a long 
period of years; and it is comforting to know that 
when the progress is slow, much may be done by 
the family physician to delay it. 
Whether we accept the view that functional hy- 
pertension is caused by an increased tonus of the 
arterioles due to the circulation in the blood of 
some unknown poisonous substance, or the view 
that it is the result of unrecognizable arterioscle- 
rosis hidden in some of the finer organ arterioles, 
it is in either case true that so-called functional 
hypertension that continues for a long time eventu- 
99 BLOOD PRESSURE 
ally becomes associated with a frank arterioscle- 
rosis. Essential hypertension has indeed been 
spoken of by some writers as the "pre-sclerotic" 
type of hypertension. The walls of the blood ves- 
sels, exposed to the increased pressure of their con- 
tained blood, sooner or later suffer damage; they 
gradually undergo fibrous thickening with conse- 
quent diminution of elasticity. At the same time, 
each beat of the enlarged heart throws its quota 
of blood into the damaged vessels with greater 
violence in order to overcome the greater resistance 
offered by the increased blood pressure. The larger 
vessels, unable longer to yield elastically to the 
inrush of blood at each heart beat, must yield 
by a gradual enlargement; hence, dilatation of the 
aorta and of the larger vessels ensues. Eventually, 
the degenerative changes already noted in the heart 
muscle itself lead to alterations in the heart wall 
that are somewhat of the nature of those that occur 
in the arteries in arteriosclerosis. Upon this dam- 
aged and over-laboring heart a still greater burden 
is ever being placed, for sclerosis of the vessel 
walls, particularly those of the smaller arteries 
and arterioles, raises the minimum diastolic blood 
100 HEART, KIDNEYS AND BRAIN 
pressure gradually ever more, as we have seen. 
A vicious circle is involved; we need scarcely dis- 
tress ourselves with too vivid contemplation of the 
inevitable final result to the patient. 
When arteriosclerosis develops in those two small 
vessels which leave the aorta just at its junction 
with the heart and run downward in the heart 
muscle itself (the coronary arteries), the nourish- 
ment of the musculature of the heart is especially 
interfered with and the stage is set for the appear- 
ance of the atrocious pain that is known as "angina 
pectoris." It is mentioned, here, merely to place 
it among the more serious complications of hyper- 
tension and arteriosclerosis. It may be remarked, 
however, in passing, that some of the most serious 
cases of angina pectoris are due to a sclerosis 
of the coronary arteries that occurs without the 
general changes that give rise to high blood pres- 
sure; in such cases the blood pressure, instead of 
being higher, may be much lower than normal. 
When we turn to the complications in which the 
function and structure of the kidneys become in- 
volved we are again confronted with the problem 
of wherein lies the first deviation from the normal. 
101 BLOOD PRESSURE 
It may be that the first step in the process of 
kidney involvement is a constriction of the renal 
(kidney) arterioles and capillaries due to some 
unknown cause (possibly a cause similar to that 
of essential hypertension), resulting in a narrow- 
ing of their lumen and consequently in a dimin- 
ished supply of blood to the glandular structures 
of the kidney which are charged with the function 
of secreting urine; poisonous products that should 
be excreted in the urine would then be retained in 
the circulation, and be responsible for a rise of 
blood pressure, either through direct stimulation 
of the arteriolar walls or through stimulation of 
the vaso-constrictor center in the brain; and this 
increased blood pressure could, in its turn, lead 
to the appearance of arteriosclerosis, which could 
still further damage the tiny blood vessels in the 
kidney (as well as in other organs) and so lead 
to a further diminution of renal function. Or, it 
may be, as some think, that the arteriosclerotic 
process is prone to develop early in the kidney and 
is the first change in the series, causing impair- 
ment of renal function; the ensuing retention of 
poisonous products could lead to spasm of the 
102 HEART, KIDNEYS AND BRAIN 
arterioles throughout the body, a pathological 
physiological response answering the need of a rise 
in the blood pressure to force more blood through 
the damaged renal vessels. The truth, we are in- 
clined to believe, is probably to be sought still 
farther back in a chain of events than at the links 
suggested by either of the views mentioned; it 
would not surprise us, if some day it should be 
determined that hypertension is not the primary 
cause of arteriosclerosis, and that arteriosclerosis 
is not the primary cause of hypertension, but that 
rather both hypertension and arteriosclerosis are 
due to the presence of some poison, of as yet un- 
known nature and origin, circulating in the blood. 
Such a hypothetical poison may turn out to be 
the original cause of the whole complex syndrome, 
in which event its nature and source and the reason 
for its non-elimination will have to be investigated. 
In the present state of our knowledge it is, perhaps, 
better not to try to arrange kidney lesion, hyper- 
tension, and arteriosclerosis in any specific order 
of sequence of occurrence, but to recognize that 
when they co-exist ("cardiovascular-renal dis- 
ease")? there is a possibility that all three may 
103 BLOOD PRESSURE 
be due, directly or indirectly, to some common, 
though still unknown, cause. 
Certain it is that changes in the walls of the 
renal arterioles often develop at an early period 
of the hypertensive malady. The nutrition of the 
secreting elements of the kidney then suffers, with 
consequent impairment of renal function. With 
the insidious advance of the process, there is actual 
death from starvation gradually of one after 
another of thousands of secreting elements. In time 
the proportion of atrophied elements may become 
so great that the kidneys shrink in size, and though 
parts of the kidneys still work very well, there is 
such a marked reduction of the filtering and se- 
creting elements that the kidneys are unequal to 
their normal tasks; renal insufficiency becomes 
recognizable through certain tests that the physician 
can make. Retention in the body of poisonous 
products that should be excreted becomes ever more 
pronounced and associated with such retention 
there is an increased rise of blood pressure. In 
some instances, the blood pressure may reach very 
high levels; in fact, the highest permanent blood 
pressures known are those that are met with in 
104 HEART, KIDNEYS AND BRAIN 
this type of kidney disease, which is commonly 
called, especially in non-medical circles, "chronic 
Bright's disease." When the condition has become 
well established, it is not uncommon to find as 
permanent levels a maximum systolic blood pres- 
sure of 200 millimeters of mercury, or more, and 
a minimum diastolic pressure of 100 to 130 milli- 
meters; instances are on record of maximal pres- 
sures exceeding even 300 millimeters of mercury! 
Along with the long-continued rise of blood pres- 
sure both arteriosclerosis and hypertrophy of the 
heart develop, in the manner already described. 
The terminal event in the patient may depend upon 
failure of either the heart or the kidneys to func- 
tion sufficiently to permit of the continuance of life. 
If the heart fail, the circulation becomes so poor 
that fluid collects in the cavities of the body and 
in the loose tissues under the skin ("dropsy") ; 
if the kidneys fail, the poisons retained may 
cause delirium, convulsions and unconsciousness 
("uraemic poisoning"). 
It remains, in connection with chronic arterial 
hypertension, to speak of the brain, the third of 
the three organs (heart, kidneys, brain) that to- 
105 BLOOD PRESSURE 
gether have been called the "tripod of life." 
Though hypertension alone or in association with 
faulty elimination by the kidneys, may give rise to 
brain symptoms such as headaches, sensations of 
pressure in the head, and dizzy spells, much more 
serious phenomena, as we shall see, may follow 
upon the occurrence of sclerosis of the small ar- 
teries of the brain. 
In any sclerotic vessels, the thickened walls me- 
chanically reduce the caliber of the vessel and this 
reduction of the internal diameter of an artery 
alters both the amount of the blood flow through 
it and the speed of the flow. These changes in the 
blood flow, together with the lessened power of 
adjusting the blood supply to the brain to changing 
needs of that organ for blood, have much to do 
with the slight mental symptoms that everyone 
recognizes as characteristic of advancing age. With 
increasing years, especially beyond the fifth and 
sixth decades, men's minds become, as a rule, less 
flexible; in later life, men sometimes find difficulty 
in mental grasp, especially when the topics dealt 
with are complicated; and they are often forgetful 
and sometimes irritable. They tend to waken early 
106 HEART, KIDNEYS AND BRAIN 
in the morning, and during the day they tire easily 
on either physical or mental exertion. There is 
a gradual narrowing of interests, a loss of power 
to do productive work, and a disinclination to new 
undertakings. No one is surprised to observe such 
symptoms in elderly persons, and physicians at- 
tribute them to the low grade of arteriosclerosis 
that normally accompanies advancing age. This 
"physiological arteriosclerosis" may not be associ- 
ated with arterial hypertension. 
Slow cerebration, however, is only one result 
of the altered blood flow in the arterioles of the 
brain, for wherever blood loiters on its journey, 
in the brain or elsewhere, especially where there is 
some diseased condition of the vessel walls causing 
narrowing and roughening of the inner surface, 
there clotting is apt to occur. The formation of 
such a clot in various small arteries and arterioles 
is not a particularly rare occurrence in arterio- 
sclerosis; it may occur in regions of the body in 
which it does not proclaim its presence by any 
marked symptoms. But in the delicate organ we 
are considering every little arterial branch nour- 
ishes some important bit of brain tissue, which 
107 BLOOD PRESSURE 
may have a special function not shared by any 
other portion. Interference with the nutrition of 
that bit of tissue, even though it be slight and 
temporary, may reveal itself by a disturbance of 
sensation, of consciousness, of motion, of speech, 
or of memory. Narrowed vessels may undergo 
spasm at times and temporarily cut off the blood 
supply. In this way arise the transient numbnesses 
and paralyses of arteriosclerotic and of hyper- 
tensive-arteriosclerotic patients. Or an artery may 
become completely stopped up, either by projec- 
tions of the altered wall into the vessel, or by a 
clot of blood. The plugged vessel in the brain 
may be very small and in a so-called "silent area" 
of the brain, injury to which can scarcely be recog- 
nized; or the artery may supply one of the "non- 
silent areas," where the least interference with 
nutrition, disturbing function, causes prompt and 
more or less prominent symptoms. Thus, as the 
result of obstruction to the flow of blood through 
a small artery in the brain, a numbness or a 
paralysis in one or more of the limbs may quietly 
appear, or one eyelid may droop helplessly over 
the eyeball; or the power of speech may be lost or 
108 HEART, KIDNEYS AND BRAIN 
greatly disturbed; or there may be a shocking loss 
of memory; or the person may even become un- 
conscious. 
This obstruction of blood flow due to clotting 
within arterioles and small arteries is called throm- 
bosis, and since the smaller or larger areas of the 
brain that are thus deprived of blood actually die 
and undergo disintegration and absorption the con- 
dition is sometimes spoken of as "softening of the 
brain." In patients with severe disease of the 
arteries of the brain, one artery after another may 
become occluded, causing a series of "softenings," 
with corresponding successive losses of brain func- 
tions. 
In thrombosis, no blood escapes from the vessels 
that are plugged; but the brain is subject to another 
sort of arteriosclerotic vascular accident that is cor- 
rectly described by the laity as the "bursting of a 
blood vessel" in the brain, and which physicians 
refer to as "cerebral hemorrhage" or "apoplexy." 
This rarely occurs except when advanced arterio- 
sclerosis of the brain vessels and marked arterial 
hypertension accompany one another, the simplest 
explanation being that the diseased vessel-wall rup- 
109 BLOOD PRESSURE 
tures under the heightened pressure of the blood. 
The explanation is upheld by the relative frequency 
of apoplexy in elderly persons immediately after 
the influence of something that we know tempo- 
rarily raises the blood pressure, for example, vio- 
lent muscular exertion (such as running for a 
train, or suddenly lifting a heavy weight), sudden 
chilling of the skin by a cold bath, coughing or 
sneezing after a big meal, alcoholic excess, or 
strong emotional excitement (anger; fright; coi- 
tus). Still, it must be acknowledged that some are 
"stricken" while lying quietly in bed; it is not so 
very uncommon for a patient to be found after a 
night in bed showing signs that indicate that a 
blood vessel has ruptured during the night. 
These patients may recover some of the functions 
that are at first lost, but when the paralysis that 
occurs is extensive, it is common to see them re- 
main permanently paralyzed in one or more parts 
of the body. The reason for partial recovery lies 
in the fact that the brain does not necessarily 
"soften" as in thrombosis. The blood that escapes 
from the broken vessel immediately into the brain 
substance does harm partly through its presence as 
110 HEART, KIDNEYS AND BRAIN 
a foreign body and partly by the pressure that 
it exerts in the brain tissue. If the blood pressure 
be high, a hemorrhage from even a small artery 
can exert considerable pressure upon the soft sub- 
stance of the brain. But often the blood is grad- 
ually absorbed and the pressure is relieved. Some 
of the symptoms pass off, those that remain depend- 
ing upon the amount of permanent injury done to 
the brain substance. 
Not only is arterial hypertension thus an indi- 
rect cause of cerebral thrombosis and hemorrhage, 
but in the case of hemorrhage the reverse is also 
true. The brain tissue is soft and yielding, but it is 
enclosed in a hard, bony, unyielding box-the 
skull. When hemorrhage occurs within the brain, 
it squeezes the brain substance against its enclosing 
walls and tends to flatten it against them. If the 
pressure process be vigorous enough some of the 
vital centers of the lower parts of the brain may 
be pressed upon and (at first) stimulated. Among 
these is the vasoconstrictor center, which, as we 
have seen, when stimulated increases the tone of 
the arteriolar system and hence raises the blood 
pressure; this in turn may increase the bleeding, 
111 BLOOD PRESSURE 
with the production of an ever increasing pressure 
within the brain, until anemia of the brain results, 
and it, with its vital centers, ceases to function. 
Apoplexy, serious as it is, does not occur as 
frequently as many people imagine. It is com- 
forting to know that of every 100 persons with 
maximal systolic blood pressure of 170 millimeters 
of mercury or over, statistics show that about 85 
may look forward to continued freedom from 
apoplexy. CHAPTER VIII 
LOW BLOOD PRESSURE ("ARTERIAL HYPO- 
TENSION") 
Although this little book on blood pressure 
concerns itself chiefly with that aspect of the sub- 
ject that chiefly interests its readers, namely, blood 
pressure above the normal range, it would seem 
worth while to note, for the sake of completeness, 
that blood pressures that range below the normal 
do occur and are sometimes of importance. 
This condition of low blood pressure, spoken 
of as "arterial hypotension," may accompany acute 
illnesses, such as measles, scarlet fever, diphtheria, 
acute rheumatic fever or typhoid fever; in pneu- 
monia, it may or may not be observed. It appears 
also in the wasting diseases (such as tuberculosis 
and cancer) and in the anemias. It is also often 
observable after a severe hemorrhage, a profuse 
diarrhea, or a prolonged vomiting-all events that 
involve the loss of considerable fluid from the 
113 BLOOD PRESSURE 
body. It occurs, too, as a symptom of surgical 
shock, that condition of profound collapse, some- 
times fatal, that may follow upon certain opera- 
tions or severe injuries. In all of the instances 
mentioned the arterial hypotension is distinctly 
secondary to a definite provocative cause and the 
blood pressure returns to its normal range after 
the underlying cause has been removed. 
There is another type, however, which, although 
not of great significance as far as the health or the 
expectation of life of the possessor is concerned, 
is still of considerable interest. It is met with 
oftenest in persons of the so-called "asthenic habi- 
tus"; that is to say in persons who are tall and 
slender, have long necks and long narrow flat 
chests, round shoulders, long extremities and feeble 
muscles. These individuals being usually thin and 
rather pale, give the impression of not being robust. 
They tire easily; their hands and feet are frequently 
cold and bluish and their palms moist; they com- 
plain often of "indigestion," of constipation and 
sometimes of headaches and of vague pains. They 
may suffer from mild mental depression, or from 
nervous symptoms of various sorts. 
114 LOW BLOOD PRESSURE 
The range of the maximum systolic blood pres- 
sure in these persons is from 90 to 115 millimeters 
of mercury and that of the minimum diastolic 
pressure from 60 to 80 millimeters. This "es- 
sential" hypotension would seem to be related in 
some peculiar way to the particular physical make- 
up above described; the abnormally low blood 
pressure must be assumed to accord with that 
''make-up" just as "normal" blood pressure is in 
accord with the "make-up" of an average indi- 
vidual. It is probable that in persons of asthenic 
habitus, the balance of the internal secretions and of 
the impulses in the vegetative nervous system is 
somehow different from what exists in average 
human beings. In support of this view it may be 
mentioned that in Addison's disease, in which there 
is disease of one of the organs of internal secretion, 
namely the suprarenal capsules, very low blood 
pressures have been observed. 
The subject of physical types is rightly receiving 
ever more attention from the modern doctor and 
much is being written in the medical books and 
journals about it. Just as abnormally low blood 
pressures are commonest in persons of asthenic 
115 BLOOD PRESSURE 
habitus, so abnormally high blood pressures occur 
most frequently in persons of the opposite type 
of build, namely in those with short necks, broad 
thick chests and a tendency to obesity. Indeed, 
physicians often refer to this type as the "habitus 
apoplecticus," making use of a term that refers to 
the liability to cerebral apoplexy of those to whom 
it is applied. Perhaps when the layman, as well 
as the physician, begins to realize that persons 
differ from each other, not alone in their physical 
appearance, but also in their physiological and 
mental reactions, and that they behave differently 
in disease and when acted upon by drugs, the happy 
day will begin to dawn when neighbors will cease 
to diagnose their ills over the back fence and the 
"patent medicine," advertised as good for nearly 
everything and "certainly for everybody regard- 
less," will become a historical curiosity, relegated 
to the limbo in which already Bishop Berkeley's tar 
water and Perkins' magnetic tractors are confined 
and whither the anti-rheumatic horse-chestnut on a 
string is finding its way. 
No better example of the necessity of the con- 
sideration of the whole person (body and mind) 
116 LOW BLOOD PRESSURE 
when studying any abnormal process could, per- 
haps, be chosen than this condition of arterial 
hypotension. On its face, abnormally low blood 
pressure would seem to indicate a departure from 
health; but when considered in the light of the 
individual make-up it takes its proper place as 
a part of a characteristic human type. That type, 
as a whole, is not a perfectly normal type; but 
the low blood pressure that occurs in it is in accord 
with the other constituents of the type. Much can 
be done to improve the physical condition and the 
physiological states in persons of the type men- 
tioned, and with the general improvement the blood 
pressure will often be maintained at a higher level. 
The measures that have been found most useful 
include the avoidance of bodily and of mental 
fatigue, the insistence upon a sufficient amount of 
sleep at regular hours, the overcoming of consti- 
pation, and the rigorous practice of moderate daily 
setting-up exercises under the watchful eye of a 
physician. Patients with low blood pressure should 
of course undergo a thorough physical examina- 
tion at the hands of a competent physician before 
taking up the routine outlined; the dangers of self- 
117 BLOOD PRESSURE 
treatment of either hypotension or hypertension 
cannot be too strongly emphasized. Just think, for 
example, how disastrous it might be for a patient 
to undertake of his own accord to treat his low 
blood pressure by active exercise if his hypotension 
were due to tuberculosis of his suprarenal capsules! CHAPTER IX 
WHAT TO DO? 
It is pleasant now to be able to turn from the 
somewhat depressing recital of the causes, the ac- 
companying conditions, and the consequences of 
chronic arterial hypertension to the more hopeful 
theme of its prevention and amelioration. Much 
may be done to ward off the appearance of the 
process; even after it has appeared and been recog- 
nized, its further advance is often preventable. 
None of us can hope to avoid some degree of hyper- 
tension and even of moderate arteriosclerosis as 
we grow older, for they are parts of the aging 
process; but we can live our lives, if we will, in 
such a way as to discourage any abnormal rise of 
blood pressure in our later years. If we are wise 
we shall take a leaf from the book of the juggler, 
the dancer, and the acrobat; like them, we shall 
not only begin our training early, but also endeavor 
to keep it up without a break. 
119 BLOOD PRESSURE 
To begin at the beginning of the hygienic regime 
that will keep the blood pressure within its proper 
bounds, we must remember that those are fortunate 
whose blood vessels and general physical make-up 
at birth and during development are of standard 
quality. No one has ever put the case better than 
Oliver Wendell Holmes when he said that if we 
would be healthy we must choose our grandparents 
wisely. Heredity is recognized to-day as a large 
factor in the determination of the cause of blood 
pressure. But since our own inheritance is a fac- 
tor beyond our control we must cheerfully accept 
the characters transmitted to us as we find them. 
When we remember, however, that we shall prob- 
ably be grandparents in our turn, we shall con- 
sider it a duty, to those who shall come after us, 
when we contemplate parenthood, to consider care- 
fully the prospects of those new beings that may 
result from the fusion of our germ cells with those 
of our mates. It is to be feared, however, that such 
eugenic considerations play as yet but a subordinate 
role in the choice of marital partners or in de- 
cisions as to the advisability of parenthood. There 
may be a few in each generation who are wise 
120 WHAT TO DO? 
enough and strong enough to guide instinct by 
reason; for the majority, instinct is likely to defy 
efforts at rational restraint. When it comes to 
making the most of our own lives, however, many of 
us will listen to good advice and some of us will 
act upon it. In early life, when acute infections 
most often attack us, the utmost care must be taken 
to insure complete recovery and to be patient dur- 
ing convalescence, if our blood vessels are to be 
protected from injuries that may dispose them to 
arteriosclerosis later. We do not know exactly how 
much vascular damage is done by measles, ty- 
phoid fever, scarlet fever, and other infectious 
diseases, but we do know that the vessels do not 
escape scot-free from the effects of the poisons 
produced by the bacteria of disease, any more than 
does the rest of the body. The man, or child, who 
rises from a sick bed prematurely and plunges 
immediately into his usual more or less strenuous 
life can surely be accused of neglect of his future 
health. The bacteria that cause bad colds, sore 
throats, and tonsillitis are capable of doing great 
harm to the heart, to the blood vessels and to the 
kidneys; much misery would be avoided if common 
121 BLOOD PRESSURE 
colds and sore throats could be prevented, or if 
persons suffering from them would submit them- 
selves promptly to a wise physician's care. 
To say that good habits of personal hygiene, 
such as adequate sleep, plain food in moderate 
quantity, proper exercise, fresh air, frequent bath- 
ing, self-control and avoidance of all excesses, 
should be impressed upon the growing child is to 
utter a platitude; but we dare not fail to utter it, 
for far too often it is assumed that youth, with 
its buoyancy and elasticity, is proof against infrac- 
tions of hygienic laws. Physicians now believe that 
many of the diseases of middle age, including the 
group of hypertensive disorders, can be followed 
back to an origin in long-established habits of 
faulty hygiene. 
As the child approaches maturity when his pro- 
ductive life begins, with all that this implies of 
increasing responsibilities and entry into the be- 
wildering complications of modern social and bus- 
iness life, it becomes even more important for him 
to "watch his step" and to remember that a healthy 
old age is not solely a gift of the gods, but rather 
a prize valiantly to be striven for. 
122 WHAT TO DO? 
The average young man of to-day does not envy 
Thoreau his lonely hut by Walden's shore, nor the 
peaceful life of the beloved entomologist of 
Provence; he desires, and rightly, the strenuous 
life of the age in office and in workshop. But if 
he be wise he will avoid complete submergence of 
himself in his work. He will cherish the ability to 
throw off his business cares and worries when he 
leaves his work for the day; for after a day of 
strenuous activity, it would be silly not to relax 
the tension to which his whole organism has been 
keyed up. Furthermore, he will put the correct 
valuation upon recreation. In his choice of hobbies 
-and every man should have at least one or two 
of these-he will see to it that they are as different 
as possible from his main occupation. He will 
also recognize that his social recreations should 
actually diminish tension and he will not permit 
himself to be drawn frequently into situations in 
which hectic excitement and dissipation lay further 
levies upon his nervous system. Of equal, if not of 
even greater, importance to him will be the ability 
to drop his work entirely at frequent intervals 
for a day or two at a time. The demand of the 
123 BLOOD PRESSURE 
Mosaic law that one day in seven be given to rest 
is only one of the proofs that this old code gave 
consideration to hygiene as well as to religion. 
Owing to the greater complexity of life, the need 
of periods of relaxation is far more imperative 
nowadays than it was in ancient times. Not only 
should week-ends and an afternoon each week be 
given to "play" of some kind, but an annual or 
semi-annual vacation should be taken regularly, 
no matter how absorbing or how exacting business 
or professional responsibilities may seem to be. 
Among the persons in this country who carry the 
heaviest responsibilities and who are animated by 
the highest sense of duty, there is a growing 
tendency to arrange for a long vacation in the 
summer, for a shorter vacation in midwinter and 
for briefer vacations at Thanksgiving and Easter. 
And the wisest of these persons take their longer 
vacations in quiet places, in the woods or on the 
water far away from the din, the bustle and the 
artificiality of town and city life. 
Remembering the relationship of arteriosclerosis 
to high blood pressure, and that the measures ad- 
vised for the prevention of the former apply also 
124 WHAT TO DO? 
to the prevention of the other, it is interesting to 
recall what the late Sir William Osler once said 
about the "wear and tear" of life.1 "The con- 
ditions of modern life," he wrote, "favor arterio- 
sclerosis, as a man is apt to work his body machine 
at high pressure, and often takes less care of it 
than of his motor. The best express engine from 
the Baldwin works, run day by day at maximum 
speed, will not last one-tenth of the time it would 
do if it were not so pushed. But nowadays, with 
the human engine it is top-speed or nothing, and 
we cannot wonder that it early shows signs of hard 
usage. In the fourth or fifth decade, even with 
the best of habits in eating and drinking, the in- 
cessant strain and anxiety of public life or of 
business may lead to degeneration of the blood 
vessels. Mental exertion is not of itself injurious, 
and the life of the student need not be one of 
great tension, but the mental exertion of the mod- 
em business man is of a different kind. Compe- 
tition is so keen and the environment so stimu- 
lating that, even without social or political am- 
1 Osler, W. Modern Medicine, Philadelphia, Lea & Febiger, 
1908. 
125 BLOOD PRESSURE 
bitions, high pressure seems a necessity. The trag- 
edies of life are largely arterial. Represented in 
the old mythology as winged, Nemesis, the goddess 
of the Inevitable, may still be pictured with a 
wheel, the wheel of life, to the ceaseless revolutions 
of which the circulation ministers. How often does 
her fatal touch call away in their prime the best 
and the bravest-whose only fault has been the 
unselfish abuse of the body machine!" 
After adequate attention to work, rest, recreation 
and mental tranquillity, the most important measure 
preventive of high blood pressure is a suitable diet. 
The quantity of food eaten is far more important 
than the quality, though both should be considered. 
Even an ordinary sensible meal causes a temporary 
rise of blood pressure, which is a normal reaction 
and not injurious; but when a meal is so large 
as to overdistend the stomach, to drag upon the 
abdominal blood vessels, to cause pressure upward 
against the diaphragm, to limit the excursion of 
the latter and so to interfere with breathing, it may 
be positively harmful; for the prolongation of di- 
gestion, the mechanical embarrassment of heart and 
the interference with breathing all throw strain 
126 WHAT TO DO? 
upon the circulatory system. If such strain be re- 
peated day after day, it is inevitable that, sooner 
or later, permanent harm will be done to the heart 
and the blood vessels. 
Big meals are apt, too, to be rich meals, in- 
clusive of a heavy meat course and of many condi- 
ments. Now it happens that foods that are highly 
seasoned with salt, pepper and mustard not only 
tempt to overindulgence at the table but are in 
themselves stimulating to the circulation and con- 
ducive to a rise in blood pressure. The so-called 
"extractives" of meat-the substances in meat that 
are soluble in boiling water and that form the 
basis of meat broths-are also stimulating. So is 
coffee, which usually tops off the large meal; and 
so is the nicotine of the after-dinner cigar. Habit- 
ually heavy meals, whether they be served at noon 
or in the evening, are among the more important 
of the factors that are concerned in the origin of 
the arterial hypertension of later life. Particularly 
obnoxious is the eating of two or three heavy meals 
per day by persons whose habits are sedentary, 
and whose lives are led indoors. To such persons 
a period of living according to the advice of the 
127 BLOOD PRESSURE 
grim English physician who urged his patient "to 
live upon sixpence a day and to earn it" might 
be salutary! 
The majority of Americans eat too much meat 
by far; there are but relatively few who are of 
normal weight or heavier who would not be better 
off physically if they reduced their meat-intake to 
a half or even to a third of the amount they have 
been accustomed to eat. Each person should make 
sure, too, that his diet is well-balanced; the ration 
should contain the proper proportions of proteins 
(meat, chicken, fish or eggs), carbohydrates (ce- 
reals, sweets), fats (butter, bacon), vitamines 
(fresh fruits, leafy green vegetables, milk), water 
and mineral salts. Each person should ascertain 
from one of the standard tables what the average 
weight is for one of his height. If his weight be 
much above this, or much below this, he should, 
under the guidance of his family physician, so 
modify his diet and his habits that his weight will 
approach the normal. 
Business men, under pressure, are all too likely 
to eat their meals hurriedly-another bad habit. 
Food that is imperfectly chewed and insalivated 
128 WHAT TO DO? 
makes excessive demands upon the organs of di- 
gestion. If, in addition, no rest be taken after 
meals, the example set by every member of the 
animal kingdom below man being ignored, and the 
eater hurry back to the concentration and the wor- 
ries of his work, two demands will be made upon 
the circulatory system where there should be but 
one; for the heart will be asked to pump extra 
blood to the vast digestive division of the circu- 
latory system and at the same time to furnish the 
brain and the muscles with the amount of blood 
that their activities require. Certainly, in time, the 
heart and the blood vessels will begin to show the 
effects of such exorbitant demands. 
Regular exercise, taken in fresh air, is essential 
to health and is one of the most important of the 
measures for the prevention of the processes that 
lead to high blood pressure. 
An interesting commentary upon the modern 
man's tendencies with regard to physical exercise 
is furnished in the prevalence of "physical culture 
magazines" and "systems of home exercise." The 
lucrative traffic in these commodities is evidence 
of the difficulties that most people experience in 
129 BLOOD PRESSURE 
taking proper exercise of their own volition with- 
out the artificial incentive of some much-lauded 
special technique. The flabby muscles and the 
steadily enlarging waist-line of the average busi- 
ness man prove him to be niggardly in his daily 
allowance of pleasant muscular exercise. Street 
cars and automobiles are so transforming customs 
that the present is sometimes spoken of as the 
"walkless age." "Girth control" competes with 
"birth control" in gaining the attention of an over- 
busy public. Occasional sprees of intensive ath- 
letics between periods of muscular inactivity will 
not serve; they may be actually harmful after 40, 
for they throw too much sudden strain on the heart 
in middle age. Physical exercise should be taken 
in moderation, but with great regularity. Morning 
calisthenics practiced for 15 or 20 minutes may be 
enough, if they contract and stretch all of the 
muscles, particularly the large muscles of the trunk, 
and are faithfully and regularly performed, 
though, in addition, two or three times a week a 
brisk walk or a ride on horseback, a round of golf, 
or a string or two at the bowling alley will be 
advantageous. Games that actively exercise the 
130 WHAT TO DO? 
body are far more interesting than monotonous 
gymnastics; they refresh the tired mind while at 
the same time they compel vigorous contractions 
of the muscles. Exercise that is interesting is far 
more likely to be regularly taken than exercise 
that is boresome. Nor should one overdo exercise; 
it should never be taken to the point of great ex- 
haustion, nor, after middle life, so violently as to 
cause marked breathlessness. 
Sleep ought to be sound and refreshing, but there 
are but few adults that "sleep as sound as careless 
infancy." The bed should not be too soft, nor the 
covering too heavy or too warm. It is surprising 
how many people are ignorant of the comfort de- 
rivable from good mattresses and box springs. The 
night dress or pajamas should be of light weight, 
and should be worn without undergarments. Cul- 
tured persons would be astonished if they knew, 
as physicians do, that there are great numbers of 
people who do not, on going to bed, remove the 
underclothing that has been worn during the day! 
Twin beds are better for sleep than a double bed. 
An abundance of fresh air at night is essential. 
The old superstition that night air is in itself 
131 BLOOD PRESSURE 
miasmic and deadly has long ago been exploded; 
it was the mosquito bite, not the night air, that 
caused malaria. If one is frail, it is not wise, of 
course, to sleep in a draught, nor where the window 
opens directly upon the sleeper; but even in small 
rooms a screen will protect one sufficiently from 
the draught of a wide open window. More and 
more people are sleeping upon open porches, in 
winter as well as in summer, to their great advan- 
tage; the modern house that is not well-supplied 
with sleeping poaches is incomplete. Most im- 
portant of all, the cares and anxieties of the day 
should be shed by the mind at bedtime just as 
thoroughly as the clothing is removed from the 
body. It should not be forgotten that the business 
of going to sleep is just as important a part of the 
twenty-four hours' duty as is that of eating, or of 
working, or of playing. Too many persons like to 
continue their "vain bibble babble" far into the 
night and go to bed only when there seems to be 
nothing else to do. And some appear to regret that 
it is necessary to go to bed at all; they have heard 
that sleep "knits the raveled sleave of care," but 
they seem to be oblivious of the fact that their 
132 WHAT TO DO? 
"sleaves" have been at all frayed. Of the amount of 
sleep that is necessary for each person it is not 
possible to speak by the book. People undoubtedly 
vary in sleep requirements. Seven hours is prob- 
ably the minimum for most grown persons; eight 
hours is, for many, a better allowance. And "early 
to bed and early to rise" is a time-worn motto 
that has not yet lost its value. 
The elimination of harmful substances from the 
body demands constant attention and is largely 
dependent upon the formation and maintenance of 
several important habits. Waste products are re- 
moved from the system through the stools, the 
urine, the sweat, and the breath; and though the 
processes of removal are almost automatic, still 
we must see to it that the machinery is kept in 
good working order and that the channels of exit 
are not allowed to become clogged. Consider, for 
instance, elimination through the stools. The bow- 
els should move satisfactorily at least once every 
day, and, best, at the same time each day. If they 
do not so move, some of the waste products are 
likely to be absorbed into the blood, where they 
may circulate and poison the tissues, before finding 
133 BLOOD PRESSURE 
their way out of the system by some other elimi- 
native route. If the kidneys be damaged in any 
way, they, in turn, may fail to accomplish their 
whole function as scavengers. The skin, too, is 
an important organ for the removal of waste prod- 
ucts, but it must be kept clean and active by bath- 
ing and friction if it is to serve adequately as a 
thoroughfare for the poisons that are given off 
through the sweat glands. Each of the trio of 
eliminators performs its functions best under spe- 
cial conditions that are provided by wholesome 
habits; thus the habit of eating liberally of green 
vegetables and fruit, and the habit of going regu- 
larly to stool will go far toward insuring a daily 
satisfactory bowel movement and the elimination of 
waste products through the alimentary tract; the 
habit of drinking plenty of water through the day 
favors elimination through the kidneys, and the 
habit of a daily bath followed by brisk friction 
keeps active the function of elimination through 
the skin. Let us then consider these habits some- 
what more in detail. 
The habit of going to stool at precisely the same 
hour each morning is perhaps the best of all ways of 
134 WHAT TO DO? 
avoiding constipation. The same five minutes each 
day should be looked forward to with the full ex- 
pectation that at that exact time the bowels will be 
ready to function. The large intestine is an organ 
that is particularly amenable to strict habit in this 
regard; indeed, it is apt to be recalcitrant if its 
owner is chronologically irregular. Regular daily 
exercise, especially exercise that involves contrac- 
tions of the muscles of the abdominal wall, is pro- 
motive of good evacuations by the bowel. Knead- 
ing the abdomen for a few minutes before rising 
in the morning is practiced with benefit by many 
people. Copious water drinking on rising, and dur- 
ing the day, between rather than with the meals, 
is also a great help to regularity of bowel move- 
ments. "Roughage" must be included in the food 
if satisfactory movements of the bowels are de- 
sired; for this reason the daily ration should in- 
clude two or more vegetables like spinach, cabbage, 
asparagus, lettuce, onions, tomatoes and celery. 
Oatmeal contains more roughage than other cereals 
and brown bread and whole wheat bread contain 
more than bread made of bolted flour. Artificial 
roughage may, sometimes with advantage, be intro- 
135 BLOOD PRESSURE 
duced in the form of bran or of agar-agar. Fruits, 
with the exception of bananas, which are consti- 
pating to some persons, should be eaten freely. 
An orange or a baked apple at breakfast time, 
stewed prunes or stewed figs as a dessert at midday 
or in the evening, and a raw apple at bedtime 
are especially helpful. 
The habit of self-drugging for constipation is 
pernicious. When, after a fair trial, there is diffi- 
culty in securing regular bowel movements by 
means of the several habits above described, a 
physician should be consulted, for the treatment 
then required may be very different in different 
persons. The person who attempts, in such cir- 
cumstances, to treat himself may easily do himself 
harm. 
The elimination of waste products through the 
kidneys is, as we have said, favored by drinking 
plenty of water. Six or eight glasses of water per 
day will not hurt the kidneys, but the drinking 
of too little water will result in the passage of a 
too-concentrated urine, which may irritate the kid- 
neys or the bladder. The faithful kidneys can be 
spared much overwork and injury if we take care 
136 WHAT TO DO? 
to maintain the other channels of elimination (bow- 
els; skin) in good function and thus keep down 
to a minimum the amounts of waste materials 
that circulate in the blood. There can be no doubt 
that the retention in the body of poisonous waste 
substances contributes to the development of dis- 
ease of the arteries and of the kidneys. Neither 
the walls of the arteries nor the delicate secreting 
elements of the kidneys can be exposed to poisons 
year after year without suffering some damage; 
and we have seen in a former chapter that damage 
to either may be accompanied, as though by an 
echo, by high blood pressure. 
The third member of the eliminative trio, the 
skin, is favored in its excretory function, as we 
have already said, by baths and by the abundant 
blood-supply that follows friction after a bath, or 
that is induced by active bodily exercise. Healthy 
persons should take a daily bath and rub the skin 
thoroughly afterwards with a rough towel. Some 
prefer hot baths, some lukewarm, and some vigor- 
ous young persons do not quail before the icy 
spigot. Warm baths are more cleansing than cold; 
and very cold baths are probably too severe in their 
137 BLOOD PRESSURE 
effects for any but the young. Those who take a 
cold plunge or shower each morning should take 
in addition a warm bath at bedtime or before the 
evening meal two or three times a week. Many 
like to take a warm shower in the morning, fol- 
lowed by a short cold shower. Though most people 
can accustom themselves to cold baths, there are 
some who do not react well to them and they 
should avoid them, or work up to them very grad- 
ually under expert direction. No matter what form 
of bath is taken, the skin should afterwards be 
dried thoroughly and be rubbed with a rough towel 
until the skin tingles and is reddened. Many, after 
drying the skin, go through a set of calisthenic 
exercises that includes rubbing of the skin with 
the palms of the hands. 
One class of poisons that gain entrance to the 
circulating blood still remains to be spoken of. 
These are the toxins that result from growth of 
bacteria in some region of the body, enter the blood 
stream and make their effects felt at a distance 
from their source. It is now a well-known fact 
that colonies of harmful bacteria may exist for a 
long time in out-of-the-way places in the body, say 
138 WHAT TO DO? 
deep in the crypts of the tonsils, or at the roots 
of the teeth, or in the sinuses about the nose, or 
in the gall bladder. Sometimes a chronically in- 
flamed appendix harbors them; or the prostate 
gland, which lies at the neck of the bladder in 
men, or certain of the organs of generation in 
women may contain such bacterial foci. Although 
the little plants that we call bacteria may not oc- 
casion, at least for a long time, any violent trouble 
at the particular spot where they grow, the poison- 
ous substances that they give off during their growth 
are absorbed by the lymph and blood flowing 
through the infected organ and are carried to all 
parts of the body. Sometimes a few of the bac- 
teria themselves get over into the blood and are 
carried to other parts of the body where they are 
killed and act as poisonous substances, or live to 
set up new foci of infection. Until the poisons are 
destroyed, neutralized or eliminated they are the 
cause of continuing injury to many of the body 
tissues; the kidneys and the joints seem to be 
especially prone to injury by them. These poisons 
are more or less steadily produced as long as the 
focus of bacterial infection exists. If the existence 
139 BLOOD PRESSURE 
of the focus He not suspected, through any local 
symptoms produced by it, as is often the case, the 
bacteria in it may continue their clandestine produc- 
tion of toxins for months or years. The oft- 
repeated entrance of the poisons into the blood is 
followed gradually by changes in the blood vessels 
and the kidneys. We must be sure, then, that no 
such "focus of infection" is allowed to exist un- 
recognized in any part of the body, if we would 
protect ourselves from injuries that may lead to 
various disturbances, among them the processes that 
lead to heightened blood pressure. 
Fortunately, modern medicine has become famil- 
iar with the dangers of these little foci of infection 
and has developed plans by which they can be 
systematically sought for, discovered and removed. 
The freedom of our bodies from these insidious 
nests of dangerous bacteria is a condition worth 
striving for. In order to make sure of it and at 
the same time to find out whether the bodily func- 
tions in general, inclusive of the blood pressure, 
are such as to indicate health and to promise se- 
curity, each person should form the habit of sub- 
jecting himself to a periodical physical examina- 
140 WHAT TO DO? 
tion by a competent physician. There is no other 
measure more likely to be of aid to us in our 
efforts to live out our threescore years and ten 
in comfort. Even in youth it is desirable that oc- 
casionally a bodily survey should be made by an 
experienced physician; but when the age of forty 
has been passed, it is folly not to take the bodily 
machine to the doctor for an overhauling at more 
or less regular intervals. The expenditure of time 
and money involved in submitting one's self once 
a year to a thorough study at the hands of some 
good practitioner of medicine need not be burden- 
some to anyone; in any case, health is so valuable 
that it is worth spending some time and money 
in order to preserve it. Fortunately, the gospel of 
prevention of disease is finding ever more ad- 
herents; there are now large numbers of persons 
who betake themselves at regular intervals, sick 
or well, to a doctor and ask him to ascertain their 
condition and to advise them so that they may 
be sure that they are doing nothing that is harmful 
or leaving anything undone that should be done 
for the preservation of health. It is only in this 
way that many of the slow, degenerative diseases 
141 BLOOD PRESSURE 
that so often develop during the years on the far 
side of forty can be guarded against or discovered 
in their incipiency and arrested. It is only in this 
way that the group of disorders of which high 
blood pressure is a symptom can be detected at a 
time when the physician can be of real service in 
preventing advance and in restoring to normal, 
functions that have only begun to be disturbed. 
The term "curative measures" is perhaps a mis- 
nomer in connection with high blood pressure, 
for there is, strictly speaking, no "cure" for chronic 
arterial hypertension. Indeed, hypertension, as we 
have said, is a symptom rather than a disease. 
It is a symptom that appears after certain changes 
in the structure and in the functions of the body 
have occurred, some of which we have been able 
to trace though others still remain unknown. The 
high blood pressure is needed for the welfare of 
the body as changed; obviously, then, unless we 
can remove the changes that have made the higher 
pressure necessary, we might do harm by directly 
lowering the blood pressure by drugs. When the 
blood pressure is beginning to climb we do well 
to enforce the general hygienic measures that have 
142 WHAT TO DO? 
been described above as applicable to healthy per- 
sons who desire to keep well. 
If the blood pressure has only just begun to rise 
and the physician's study reveals faults of hygiene, 
or focal infection, the correction of the hygienic 
faults or the removal of the infectious focus may 
be followed by a return of the blood pressure 
to normal; in such a case, the physician may have 
some right to assert that he has "cured" the disease- 
process of which the rising blood pressure was a 
symptom. If the high blood pressure has been 
long continued, and the processes that underlie it 
have become fixed and irreparable, there can be 
only amelioration; for the hypertension, it must 
be reiterated, is only an adaptation of the me- 
chanics of the circulatory system to certain under- 
lying changes. It is these changes, whatever they 
may be, that must be sought out and where possible 
removed. In their early stages, they may be re- 
movable; later on, they become fixed and irre- 
movable. At no stage is it the part of wisdom to 
treat results only and to let causal conditions stand. 
We have emphasized the fact that the use of 
drugs to reduce high blood pressure directly, ex- 
143 BLOOD PRESSURE 
cept in certain emergencies, is not rational and is 
rapidly falling into disuse and disrepute. Improve- 
ment of the patient's habits or changing them to 
suit his altered needs are the main resources of 
the physician in the management of patients who 
are found to have a high blood pressure. The pa- 
tient is taught how to divorce worry, hurry and ex- 
cesses of all sorts from his routine. It is desirable 
that his life should be calm and quiet; that he be 
freed from too many business and social cares, 
especially from those that tax his emotional nature. 
Relaxation should supplant tension. His sleep 
should be restful and plentiful; the food he eats 
should be moderate in amount and simple in char- 
acter and he should limit rigidly his intake of 
meat; meat extractives and condiments should be 
eschewed. He should favor elimination through 
intestine, kidneys and skin by the methods already 
described. He should see to it that focal infections, 
in teeth, tonsils, sinuses, or elsewhere are hunted 
down and eradicated. He may have to pay some 
special attention to occupation, to climate, and to 
altitude; and it may be that certain patients will 
144 WHAT TO DO? 
at times require special mechanical or electrical 
treatments or a sojourn at some spa. 
It is no part of the function of a small treatise 
intended for the general public to discuss the treat- 
ment of those later stages of patients with high 
blood pressure in which complications on the part 
of the heart, the kidneys, or the brain have begun 
to cause symptoms. Nothing would be gained by 
it. By the time such symptoms have arrived, 
even the most obtuse patient is likely to have 
realized the necessity of relying wholly upon his 
physician for direction. 
The writers of this volume will have failed in 
what they set out to do, if he who has read thus far 
has not learned that both in the prevention and 
treatment of the conditions that are associated with 
increased blood pressure, the only safe course to 
pursue is to feel a strong responsibility for the 
observance of good personal hygiene and to turn 
at regular intervals to the family doctor for super- 
vision and advice. No universal method of pre- 
vention of the hypertensive diseases can be suc- 
cessfully applied, nor is any single remedy a 
panacea after the maladies have developed. This 
145 BLOOD PRESSURE 
small volume is intended to point out where health 
lies and to describe the paths that lead to it; to 
hearten the health-seeking traveler on his way; to 
warn him against the seeming short-cuts into which 
quackery would lure him; and to assure him that, 
though few reach the goal of perfect health, many 
can live very comfortably within sight of it, if they 
are willing to observe a few simple but exceed- 
ingly important hygienic rules. GLOSSARY 
Abstemiousness, avoid- 
ance of excess. 
Accelerator nerves of the 
heart, nerves whose im- 
pulses quicken the heart 
beat. 
Anaemia, any one of sev- 
eral diseases of the 
blood. 
Anaesthesia, unconscious- 
ness produced by ether, 
chloroform, etc. 
Analogue, that which cor- 
responds with some other 
thing. 
Analogy, resemblance. 
Aneroid, without liquid; 
used of barometers and 
other gauges in which 
liquid (mercury, etc.) is 
replaced by some ar- 
rangement of springs. 
Animate, living. 
Aorta, the largest artery; 
it receives blood directly 
from the left ventricle of 
the heart. 
Apoplexy, a condition due 
to injury to a blood ves- 
sei within the brain. The 
vessel may rupture or 
may be clogged by a clot. 
There may be sudden or 
gradual unconsciousness, 
with paralysis. 
Arterial tree, the aorta 
and its branches. 
Arteries, blood vessels 
which conduct the blood 
from the heart. 
Arteriolar, pertaining to 
the arterioles. 
Arterioles, the smallest 
arteries. They connect 
the arteries and the capil- 
laries. 
Atonic, lacking "tone"; 
see "tone." 
Atrophy, a wasting away. 
Auricle, the upper cham- 
ber in either side of the 
heart. 
Autonomic nervous sys- 
tem, the special system 
of nerves which have to 
do with the control of 
involuntary function. 
147 GLOSSARY 
Baleful, harmful. 
Barometric pressure, the 
pressure of the atmos- 
phere as measured by 
the barometer. 
Bile, the secretion of the 
liver. 
Brachial artery, the large 
artery in the upper half 
of the arm. 
Bright's disease, a com- 
mon form of kidney 
trouble. 
Caliber, diameter of the 
bore of a tube; for in- 
stance, of an artery. 
Capillaries, the smallest 
bloodvessels; they trans- 
mit blood from arterioles 
to venules. 
Cardiac, pertaining to the 
heart. 
Cerebration, action of the 
brain, as in thinking. 
Cerebrospinal, pertaining 
to the brain and spinal 
cord. 
Circulatory system, heart 
and blood vessels con- 
sidered as a whole. 
Clinical, literally, pertain- 
ing to a bed; hence, in 
medicine, pertaining to 
the study of health and 
disease in the patient 
himself. 
Coitus, sexual congress. 
Concomitant, accompany- 
ing. 
Confluence, junction. 
Conserved, maintained. 
Contractile, tending or 
able to contract; oppo- 
site of expansile. 
Coordination, harmonious 
adjustment. 
Corollary, something that 
naturally follows. 
Corpuscles of the blood, 
blood cells. 
Cutaneous, pertaining to 
the skin. 
Degeneration, state or 
process of impairment; 
deterioration. 
De motu cordis, "concern- 
ing the action of the 
heart." 
Deplete, to empty; to de- 
prive of completely. 
Diastole, the period of 
time during which the 
heart muscle is relaxed 
and at rest. 
Diaphragm, the muscular 
partition between chest 
and abdomen; the muscle 
148 GLOSSARY 
chiefly concerned with 
the act of breathing. 
Disparity, unlikeness. 
Divergence, a turning 
aside; a deviation; a 
varying from the nor- 
mal. 
Dogmatically, stating an 
opinion, without proof, 
as if it were a fact. 
Dysfunction, imperfect 
function. 
Egress, act of going out, 
of leaving, of passage 
out of. 
Elaborated, produced; 
manufactured. 
Exhale, to breathe out. 
Expansile, tending or able 
to expand; opposite of 
contractile. 
Familial, occurring in 
families; used, in medi- 
cine, of characteristics 
and diseases which may 
appear in several mem- 
bers of a family and in 
more than one genera- 
tion. 
Fatigue, weariness from 
exertion. 
Functional, concerned 
with function; not involv- 
ing a change in structure. 
Opposed to organic. 
Gastric, pertaining to the 
stomach. 
Gastro - intestinal canal, 
the stomach and the in- 
testines, considered as a 
whole. 
Hemorrhage, bleeding; 
the word is not limited 
to bleeding from the 
lungs, nor does it mean 
the escape of a large 
amount of blood. Any 
degree of bleeding, from 
one drop up, in any part 
of the body, is a hemor- 
rhage. 
Hydrostatic, pertaining to 
the laws of the behavior 
of fluids under various 
conditions. 
Hygiene, the science of the 
preservation of health. 
Hyperpiesis, continued 
high blood pressure with- 
out demonstrable cause. 
Hypertension, maximum 
(systolic) blood pressure 
persistently above the 
average; also the state 
in which such a condi- 
tion persists. 
149 GLOSSARY 
Hypertonus, minimum 
(diastolic) blood pres- 
sure persistently above 
the average; also the 
state in which the condi- 
tion persists. 
Hypotension, maximum 
(systolic) blood pressure 
persistently below the 
average; also the state 
in which such a condi- 
tion persists. 
Hypothetical, existing 
only in theory; not 
proved. 
Hypotonus, minimum (di- 
astolic) blood pressure 
persistently below the 
average; also the state 
in which such a condi- 
tion persists. 
Impoverished, made poor; 
deprived of. 
Inanimate, not living. 
Induced, brought about; 
caused. 
Inhibitory, tending to stop 
or check. 
Inimical, unfavorable; ad- 
verse. 
Innocuous, harmless. 
Inordinate, excessive. 
Insalivated, saturated with 
saliva. 
Insidious,treacherous; ap- 
pearing not so bad as it 
really is (when applied 
to a disease). 
Inspiration, act of draw- 
ing in the breath. 
Intermittent, occurring at 
intervals; not continuous. 
Internal secretion, any 
product of gland action 
which is delivered by the 
gland directly to the cir- 
culating blood stream. 
The thyroid gland, for 
instance, is a gland of 
internal secretion. 
Intoxication, poisoning. 
Kinetic, concerned with 
motion. 
Lacteals, the channels 
through which flow food 
materials absorbed from 
the intestines; they empty 
into the large veins. 
Latent, hidden. 
Ligament, a band or 
strand of tough fibrous 
tissue which holds bones 
together at joints or 
which sustains organs in 
place. 
Lumen, the cavity of a 
blood vessel. 
150 GLOSSARY 
Malady, illness, disease. 
Maximum, maximal, 
greatest, highest. 
Mediate, to effect; to bring 
about. 
Metabolic, pertaining to 
all the processes, taken 
as a whole, by which the 
body assimilates food, 
builds up its tissues, 
utilizes them to produce 
energy and maintain life, 
and excretes waste ma- 
terials. 
Miasmic, malarial. 
Millimeter, one-thousandth 
part of a meter (a meter 
equals 39.37 inches). 
Minimum, minimal, least, 
lowest. 
Mm., millimeters. 
Morbid, pertaining to dis- 
ease. 
Motor nerves, those nerves 
which carry impulses 
from the brain to the 
muscles. 
Musculature, the muscles 
of the body or of any 
part of it. 
Noxious, poisonous, harm- 
ful. 
Obesity, fatness. 
Occluded, stopped up, 
plugged. 
Organ, any part of the 
body intended to per- 
form a special function, 
as the brain, heart, stom- 
ach, kidneys, etc. 
Organic, pertaining to an 
organ of the body, and 
particularly to its struc- 
ture. Organic disease 
involves changes in body 
structures. Opposed to 
functional. 
Palpate, to feel with the 
fingers. 
Pancreatic juice, the se- 
cretion of the pancreas. 
Paralysis, loss of the pow- 
er of motion or of sen- 
sation. 
Pathological, pertaining to 
disease. 
Pathologist, one who stud- 
ies conditions produced 
by disease in organs of 
the body. 
Periodic, occurring at reg- 
ular intervals. 
Periphery, the edge which 
bounds a surface; periph- 
eral vessels; those far 
away from the heart. 
151 GLOSSARY 
Perturbation, agitation of 
mind; anxiety. 
Phenomenon, any observ- 
able fact or event. 
Physiological, occurring 
as part of the normal ac- 
tivities of the body. 
Pliable, flexible; supple. 
Post mortem, "after 
death." 
Potential, having power; 
potential energy: stored- 
up energy. 
Presclerotic, occurring in 
advance of sclerosis. 
Preventive medicine, that 
branch of medicine which 
aims to prevent the oc- 
currence of disease. 
Psychic, pertaining to the 
mind. 
Pulmonary, pertaining to 
the lungs. 
Pulse, the throbbing in the 
arteries caused by the 
passage of the wave sent 
out by the heart at each 
beat. 
Pulse pressure, difference 
(in figures) between max- 
imum (systolic) blood 
pressure and minimum 
(diastolic) blood pres- 
sure. 
Radial artery, the artery 
at the wrist in which the 
pulse is usually counted. 
Reciprocal, done by each 
to the other. 
Recumbent, lying down. 
Renal, pertaining to the 
kidney. 
Replenishment, refilling; 
resupplying. 
Respiration, the act of 
breathing. 
Retrograde, in a backward 
direction. 
Rhythmical, regularly; 
occurring with regular- 
ity. 
Rupture, to break; applied 
to a blood vessel the wall 
of which gives away, with 
ensuing hemorrhage. 
Saliva, spittle. 
Secretory (of glands), 
possessing the function 
of secretion; (of nerves) 
nerves leading to such 
glands. 
Senescent, growing old. 
Sensory nerves, those 
nerves which carry im- 
pulses from the organs 
to the brain. 
Simultaneous, occurring 
at the same moment. 
152 GLOSSARY 
Tendon, a band or strand 
of tough fibrous tissue 
hrough which muscles 
are attached to bones. 
Tensing, making tense. 
Theoretical, pertaining to 
theory; conjectural; not 
proved. 
Thrombosis, clotting of 
blood within a vessel. 
Tissue, any collection of 
cells in the body into a 
definite structure. Thus 
there is bone tissue, nerve 
tissue, connective tissue, 
etc., each characterized 
by a special sort of cell. 
Tone, the state of slight 
contraction in which all 
healthy muscle, both vol- 
untary and involuntary, 
is kept by means of con- 
tinuous slight stimuli 
brought to it by the 
nerves. 
Tortuous, crooked. 
Toxin, poison. 
Vascular, pertaining to 
the blood vessels. 
Vasoconstrictor, tending 
to cause a constriction of 
the blood vessels, princi- 
pally of the small arter- 
ies and arterioles. 
Skeletal muscles, the 
muscles attached to the 
skeleton. 
Sphygmomanometer, an 
instrument for measuring 
the blood pressure. 
Spinal column, the back- 
bone. 
Stethoscope, an instrument 
for listening to sounds 
made by heart and lungs. 
Stimulus, that which ex- 
cites action. Thus light 
is a stimulus to the eye; 
motor nerve impulses are 
stimuli to the muscles to 
which they travel. 
Streptococcus, a common 
bacterium, or "germ." 
Suprarenal capsules, 
small glands of internal 
secretion situated above 
the kidneys. 
Sympathetic nervous 
system, a part of the 
autonomic nervous sys- 
tem. 
Symptom, an evidence of 
disease. 
Syndrome, a group of 
symptoms occurring to- 
gether. 
Systole, the period of time 
during which the heart 
muscle is in contraction. 
153 GLOSSARY 
Vasodilator, tending to 
cause a dilatation of 
the blood vessels, princi- 
pally of the small arteries 
and arterioles. 
Vegetative nervous sys- 
tem, see autonomic nerv- 
ous system. 
Veins, the blood vessels 
which return the blood 
from the organs to the 
heart. 
Vena cava, inferior, the 
large vein through which 
blood flows from trunk 
and legs to the right 
auricle of the heart. 
Vena cava, superior, the 
large vein through which 
blood flows from head, 
neck and arms to the 
right auricle of the heart. 
Venous, pertaining to the 
veins. 
Ventricle, the lower cham- 
ber in either side of the 
heart. 
Venules, the smallest 
veins; they receive blood 
from the capillaries and 
transmit it to the larger 
veins. 
Vessels (or blood ves- 
sels), the tubes through 
which blood flows. 
Viscosity, stickiness; the 
quality of being sticky, 
ropy, or glutinous. 
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