CHRONIC DISEASES.--DISEASE OF THE HEART AS AN EXAMPLE.--THE STRUCTURE
AND FUNCTION OF THE HEART.--THE ACTION OF THE VALVES.--THE PRODUCTION
OF HEART DISEASE BY INFECTION.--THE CONDITIONS PRODUCED IN THE
VALVES.--THE MANNER IN WHICH DISEASE OF THE VALVES INTERFERES WITH
THEIR FUNCTION.--THE COMPENSATION OF INJURY BY INCREASED ACTION OF
HEART.--THE ENLARGEMENT OF THE HEART.--THE RESULT OF IMPERFECT WORK OF
THE HEART.--VENOUS CONGESTION.--DROPSY.--CHRONIC DISEASE OF THE
NERVOUS SYSTEM.--INSANITY.--RELATION BETWEEN INSANITY AND
CRIMINALITY.--ALCOHOLISM AND SYPHILIS FREQUENT CAUSES OF
INSANITY.--THE DIRECT AND INDIRECT CAUSES OF NERVOUS DISEASES.--THE
RELATION BETWEEN SOCIAL LIFE AND NERVOUS DISEASES.--FUNCTIONAL AND
ORGANIC DISEASE.--NEURASTHENIA.
Chronic diseases are diseases of long duration and which do not tend
to result in complete recovery; in certain cases a cause of disease
persists in the body producing constant damage, or in the course of
disease some organ or organs of the body are damaged beyond the
capacity of repair, and the imperfect action of such damaged organs
interferes with the harmonious inter-relation of organs and the
general well-being of the body. The effect of damage in producing
chronic disease may not appear at once, for the great power of
adaptation of organs and the exercise of reserve force may for a time
render the damage imperceptible; when, however, age or the
supervention of further injury diminishes the power of adaptation the
condition of disease becomes evident. Chronic disease may be caused by
parasites when the relation between host and parasite is not in high
degree inimical, as in tuberculosis, gonorrhoea, syphilis, most of the
trypanosome diseases and the diseases produced by the higher
parasites. In certain cases the chronic disease represents really a
series of acute onsets; thus in the case of the parasites there may be
periods of complete quiescence of infection but not recovery, the
parasites remaining in the body and attacking when the defences of the
body are in some way weakened. In such cases there may be temporary
immunity produced by each excursion of the disease, but the immunity
is not permanent nor is the parasite destroyed. There is a further
connection between chronic disease and infection in that the damage to
the organs, which is the great factor underlying chronic disease, is
so often the result of an infection.
The infectious diseases are those of early life; chronic disease, on
the other hand, is most common in the latter third of life. This is
due to the fact that in consequence of the general wear of the body
this becomes less resistant, less capable of adaptation, and organic
injury, which in the younger individual would be in some way
compensated for, becomes operative. The territory of chronic disease
is so vast that not even a superficial review of the diseases coming
under this category can be attempted in the limits of this book, and
it will be best to give single examples only, for the same general
principles apply to all. One of the best examples is given in chronic
disease of the heart.
The heart is a hollow organ forming a part of the blood vascular
system and serving to give motion to the blood within the vessels by
the contraction of its strong muscular walls. It is essentially a
pump, and, as in a pump, the direction which the fluid takes when
forced out of its cavity by the contraction of the walls diminishing
or closing the cavity space, is determined by valves. The contraction
of the heart, which takes place seventy to eighty times in a minute,
is automatic and is due to the essential quality of the muscle which
composes it. The character, frequency and force of contraction,
however, can be influenced by the nervous system and by the direct
action of substances upon the heart muscle. The heart is divided by a
longitudinal partition into a right and left cavity, and these
cavities are divided by transverse septa, with openings in them
controlled by valves, each into two chambers termed _auricle_ and
_ventricle_. The auricle and ventricle on each side are
completely separated.
The circulation of the blood through the heart is as follows: The
blood, which in the veins of the body is flowing towards the heart,
passes by two channels, which respectively receive the blood from the
upper and lower part of the body, into the right auricle. When this
becomes distended it contracts, forcing the blood into the right
ventricle; the ventricle then contracts and sends the blood into the
arteries of the lungs, the passage of blood into the auricle being
prevented by valves which close the opening between auricle and
ventricle when the latter contracts upon its contents. When the
ventricle empties by its contraction the wall relaxes and the back
flow from the artery is prevented by crescentic-shaped valves placed
where the artery joins the ventricle. A similar arrangement of valves
is on the left side of the heart. The pressure given the blood by the
contraction of the right ventricle sends it through the lungs; from
these, after it has been oxygenated, it passes into the left auricle,
then into the left ventricle and from this into the great artery of
the body, the aorta, which gives off branches supplying the
capillaries of all parts of the body. Both of the auricles and both of
the ventricles contract at the same, time, the ventricular contraction
following closely upon the contraction of the auricles. Contraction or
systole is followed by a pause or diastole during which the blood
flows from the veins into the auricles. The work which the right
ventricle accomplishes is very much less than that of the left, and
the right ventricle has a correspondingly thinner wall. The size of
the heart is influenced by the size and the occupation of the
individual being larger in the large individual than in the small, and
larger in the active and vigorous than in the inactive. Generally
speaking, the heart is about as large as the closed fist of its
possessor.
Imperfections of the heart which interfere with its action may be the
result of failure of development or disease. An imperfect heart which
can, however, fully meet the limited demands made upon it in
intra-uterine life, may be incapable of the work placed upon it in
extra-uterine life. Children with imperfectly formed hearts may be
otherwise perfect at birth, but they have a bluish color due to the
imperfect supply of the blood with oxygen, and are known as blue
babies. The condition becomes progressively worse due to the
progressive demands made upon the heart, and death takes place after
some days or months or years, the time depending upon the degree of
the imperfection.
Much of the damage of the heart in later life is due to infection. The
valves of the heart are a favorite place for attack by certain sorts
of bacteria which get into the blood. This is due to the prominent
position of the valves which brings them in contact with all the blood
in the body, the large extent and unevenness of the surface and to the
rubbing together and contact of their edges when closed. At the site
of infection there is a slight destruction of tissue and on this the
blood clots producing rough wart-like projections. The valves in some
cases are to a greater or less extent destroyed, they may become
greatly thickened and by the deposit of lime salts converted into
hard, stony masses. Essentially two conditions are produced. In one
the thickened, unyielding valves project across the openings they
should guard, and thus by constricting the opening interfere with the
passage of blood either through the heart or from it. In the other the
valves are so damaged that they cannot properly close the orifices
they guard, and on or after the contraction of the cavities there is
back flow or regurgitation of the blood. If, for instance, the orifice
of the heart into the aorta is narrowed, then the left ventricle can
only accomplish its work of projecting into the aorta a given amount
of blood in a given time by contracting with greater force and giving
a greater rapidity to the stream passing through the narrow orifice.
This the heart can do because, like all other organs of the body, it
has a large reserve force which enables it, even suddenly, to meet
demands double the usual, and like all other muscles of the body it
becomes larger and stronger by increased work. The condition here is
much simpler than when the same valve is incapable of perfect closure,
or when both obstruction and imperfect closure, are combined as they
not infrequently are. In such cases the ventricle must do more than in
the first case. It must force through the orifice, which may be
narrowed, the amount of blood which is necessary to keep up the
pressure within the aorta and give to the circulation the necessary
rapidity of flow, and also the amount which flows back into the heart
through the imperfectly acting valve. This it can do by contracting
with greater force upon a larger amount of blood, the cavity becoming
enlarged to receive this. Not only may such damage to the valves be
produced, but the muscular tissue of the heart may suffer from
defective nutrition or from the effect of poisons, whether these are
formed in the body as the effect of disease or introduced from
without; or in consequence of disease in the lungs the flow of blood
through them may be impeded, or disease elsewhere in the body, as in
the kidneys may, by increasing the pressure of the blood within the
arteries, throw more than the usual amount of work upon the heart.
The power of the heart in meeting these conditions, however various
they are and however variously they act, seems little short of
marvellous, and it goes on throwing three and one-third ounces of
blood seventy or eighty times a minute into a tube against nine feet
of water pressure, working often perfectly under conditions which
would be fatal to a machine. As long as this goes on the injury is
said to be compensated for; the increased work which the heart is able
to accomplish by the exercise of its reserve force and by becoming
larger and stronger enables it to cope with the adverse conditions.
With increased demand for work there is a gradual diminution of the
reserve force. An individual may be able to carry easily forty pounds
up a hill and by exerting all his force may carry eighty pounds, but
if he habitually carries the eighty pounds, even though the muscles
become stronger by exercise the load cannot be again doubled. The
dilatation of the heart which is so important in compensation is
fraught with danger, because any weakening of the muscle increases the
dilatation, until a point is reached when, owing to the dilatation of
the orifices between auricles and ventricles, the valves become
incompetent to close them.
When the heart is not able to accomplish its work, the effect of the
condition becomes apparent by the accumulation of blood within the
veins and a less active circulation. This affects the nutrition and
the capacity for work of all the organs of the body, and the imperfect
function of the organs may in a variety of ways make still greater
demands upon an already overloaded heart. Other conditions supervene.
The increased pressure within the veins and capillaries due to the
impossibility of the blood in the usual amount passing through or from
the heart increases the amount of fluid in the tissues. There is
always an interchange between the blood within the vessels and the
fluid outside of them; the passage of fluid from the vessels is
facilitated by the increased pressure within them, just as pressure
upon a filtering fluid increases the rapidity of filtration, and the
increase of pressure within veins and capillaries impedes passage of
tissue fluid into them. The fluid accumulates within the tissues
leading to dropsy, or the accumulation may take place in some of the
cavities of the body. The diminished flow of blood through the lungs
prevents its proper oxygenation; this may also be interfered with by
the accumulation of fluid within the air spaces of the lungs.
Every additional burden thrown upon the heart increases the evil. In
women the additional burden of pregnancy may suffice to overcome a
compensation which has been perfect, and the same may result from an
acute attack of disease. Age, diminishing as it does the capacity for
work in all organs, diminishes the compensation capacity of the heart,
and a heart which at the age of forty acts perfectly may break down at
the age of fifty. Compensation may be gained in other ways, as by
reducing the demand made upon the heart by changing the mode of life,
by leading an inactive rather than an active life, by avoiding
excitement or any condition which entails work of the heart. Social
conditions are of great importance; it makes a great difference
whether the unfortunate possessor of such a heart be a stevedore whose
capital lies in the strength of his muscles, or a more fortunately
placed member of society for whom the stevedore works and whose
occupation or lack of occupation does not interfere with the
adjustment of his external relations to the condition of his heart.
Disease of the nervous system does not differ from disease elsewhere.
The system is complex in structure and in function. It consists in
nerves which are composed of very fine fibrils distributed in all
parts of the body and serve the purpose of conduction, and a central
body composed of the brain and spinal cord which is largely cellular
in character; it receives impressions by means of the nerves and sends
out impulses which produce or affect action in all parts. By means of
the organs of special sense, the brain receives impressions from the
outer world which it transforms into the concepts of consciousness.
Many of the impressions which the central nervous system receives from
nerves other than those of special sense and even many of the
impressions from these and the impulses which it sends out do not
affect consciousness. The memory faculty is seated in the brain and
all parts of the brain are closely connected by means of small nerve
fibres. The nervous system plays an important part in the internal
regulation and coordination of all parts of the body, and it is by
means of this that the general adjustment of man with his environment
is effected.
Malformations of the brain, except very gross conditions which are
incompatible with extra-uterine existence, are not very common. At
birth those parts of the brain which are the seat of memory and what
are understood as the higher faculties are very imperfectly developed.
Variations in structure are extremely common, there are differences in
different individuals in the nerves and in the number, size, form and
arrangement of the nerve cells, and so complex is the structure that
considerable variation can exist without detection. The tissue of the
central nervous system has a considerable degree of resistance to the
action of bacteria, but is, however, very susceptible to injury by
means of poisons. Serious injury or destruction of tissue of the brain
and spinal cord is never regenerated or repaired, but adjustment to
such conditions may be effected by reciprocity of function, other
cells taking up the functions of those which were destroyed.
Certain parts of the brain are associated with definite functions;
thus, there are areas which influence or control speech and motion of
parts as the arm or leg, and there are large areas known as the silent
areas whose function we do not know. All activity of the central
nervous system, however expressed, is due to cell activity and is
associated with consumption of cell material which is renewed in
periods of repose and sleep. Fig. 13 shows a nerve cell of a sparrow
at the end of a day's activity and the same after the repose of a
night.
Diseases of the nervous system have a special interest in that they so
often interfere with man in his relations with his fellows. In
diseases of other organs the disturbances set up concern the
individual only. Thus, others need not be disturbed save by the
demands made on their sympathies by an individual with a cold in the
head or a cancer of the stomach. Disease of the nervous system is
another affair, instead of those reactions and expressions of activity
to which we are accustomed and to which society is adjusted, the
reactions and activities are unusual and the individual in consequence
does not fit into the social state and is said to be anti-social.
There are all possible grades of this, from mere unpleasantness in the
social relations with such an individual, to states in which he is
dangerous to society and must be isolated from it. Insanity is an
extreme case. There is no disease signified in the expression, but it
is merely a legal term to designate those individuals whose actions
are opposed to the social state and who are not responsible for them.
In insanity there is falsity in impressions, in conceptions, in
judgment, a defective power of will and an uncontrollable violence of
emotion. The individual is prevented from thinking the thoughts or
feeling the feelings and doing the duties of the social body in the
community in which he lives. The insane are out of harmony with their
social environment, but not necessarily in opposition to it.
There is no very sharp line between insanity and criminality. The
criminal is in direct antagonism to the laws of social life. An insane
person may cause the same injury to society as a criminal, but his
actions are not voluntary, whereas the criminal is one who can control
his actions, but does not. Mentally degenerated persons, however, can
be both insane and criminal. Whatever the state of society, this
reprobates the actions of one opposed to it; in a society in which it
were usual to appropriate the possessions of others or to devour
unpleasant or useless relatives, virtue and lack of appetite would be
reprobated as unsocial.
The symptoms of insanity or the manner in which the defective action
of the brain expresses itself and the various underlying pathological
changes vary, and by combining these it has been possible to subdivide
insanity into a number of distinct forms. There are both intrinsic and
extrinsic causes of insanity. The intrinsic are the structural
differences in the brain as compared with the normal or usual, whether
these are due to imperfection in development or to defective heredity
or to the injury of disease; the extrinsic causes are those which come
from without and bring the intrinsic into activity. Syphilis is a
frequent cause of insanity, and probably the only cause of the
condition known as general paralysis of the insane, acting by means of
the injury which it produces in the cortex of the brain. The abuse of
alcohol is another fertile cause, but the changes produced in this are
not so obvious as in the case of syphilis. Tumors of the brain are not
infrequently a cause, and the same is true of infections, even those
not located in the brain. How susceptible the brain is to the effects
of the toxines of the infectious diseases is shown in the frequency of
delirium in these diseases. There is an interesting relation between
this and alcoholism. Alcohol abuse may produce injury, but not
sufficient to manifest itself under ordinary conditions; when,
however, the action of toxic substance is superadded to the effect of
the alcohol the delirium of fever is more marked.
Probably of greater importance than the acquired pathological
conditions of the brain in producing insanity is a congenital
condition in which the nervous system is defective. The most fertile
cause of insanity lies in the inheritance; by this it must not be
understood that insane parents produce insane offsprings, but that
conditions inherited from immediate or remote ancestors appear in a
diminished resistance of the nervous system which is sooner or later
expressed as insanity. Given such a defective nervous system,
extrinsic conditions which would have no effect on another individual
or would be felt in different ways may produce insanity. In these
cases occupation plays a great role. The excitement and privations of
war especially in the tropics and the ennui of camps leads to insanity
in soldiers; occupations such as that of the baker in which there is
loss of sleep and the mental strain of students can all act in the
same way. A woman who gives no sign of nervous defect may become
insane under the strain of pregnancy.
Although insanity is determined by the social relations of man, that
part of the social organization which is termed _Society_, and
which has been developed by the idle as a diverting game, is a fertile
source of nervous disease and even of insanity, affecting particularly
females. The strenuosity of the life, the nervous excitement
alternating with ennui, the lack and improper times of sleep, the lack
of rest and particularly of restful occupation, the not infrequent use
of alcohol in injurious amounts, are all factors calculated to make a
defect operative. The so-called "coming out" of young girls is an
important element in the game, and their headlong plunge into such a
life at a period under any conditions full of danger to the nervous
system is especially to be reprobated. If we consider the influence of
the game in other respects as conducing to lack of moral sense, to
alcoholic abuse (for without the seeming stimulation, but which is
really the blunting of impressions which alcohol brings, the game
would not be possible), to discontent, to mental enfeeblement, it is
all bad. Curiously enough the game is one which in all periods has
been played by the idle, but its evil influence is greater now than
before when it was the game of royalty chiefly, because there are now
more people living from the work of others.
The unusual mental action of the insane not infrequently expresses
itself by suicide. The analysis of three hundred deaths from suicide
showed pathological changes in the brain in forty-three per cent, and
when we think that mental disturbances are very often without
recognizable anatomical changes after death, the percentage is very
large. In another analysis of one hundred and twenty-four suicides
forty-four of these were mentally affected to various degrees. Five of
the men and seven women were epileptics, in ten of the families there
was hysteria, twenty-four of the men and four of the women were
chronic alcoholics.
It is extremely difficult at the present time to say whether insanity
is increasing. Statistics in all lands giving the numbers committed to
insane hospitals show on their face a great increase, but so many
factors enter into these statistics that their value is uncertain.
There is now an ever-increasing provision for the care of the insane.
Owing to the recognition of insanity as a part of nervous disease and
its separation from criminality there is no longer the same attempt to
conceal it as was formerly the case, and hospitals for the insane are
no longer associated with ideas of Bedlam. It is generally believed
that modern conditions in the hurry and excitement of life, and the
extreme social differences, the greater urban life, the greater
extension of factory life, all tend to an increase in insanity, but
there is no absolute proof that this is true. We know very little
about insanity in the Middle Ages, but the conditions then were not
conducive to a quiet life. There prevailed then as now excess and
want, luxury and poverty, enjoyment and deprivations, balls and dinner
parties and other features of the social game. There were factions in
the cities, public executions, not infrequent sieges, scenes of
horror, epidemics, famines, and all these combined with religious
superstition and the often unjust and cruel laws should have been
factors for insanity. There were actual epidemics of insanity
affecting masses of the population, as shown in the children's
crusade, the Jewish massacres and the dancing mania in the Rhine
provinces. Where civilization seems to be the highest, statistics show
the most insane, but this most probably depends upon better
recognition of the condition and better provision for asylum care.
The so-called functional diseases have a close relation with diseases
of the nervous system, for they chiefly concern the reactions of nerve
tissue. Disease expressing itself in disturbance of function only,
does not seem to fit in with the conceptions of disease which have
been expressed, nor can we imagine a disturbance of function which
does not depend upon a change of material. Living matter does not
differ intrinsically from any other sort of matter; like other matter
its reactions depend upon its composition structure[1] and the
character of the action exerted upon it. By functional disease there
is expressed merely that no anatomical or chemical change is
discoverable in the material which gives the unusual reaction. The
further our researches into the nature of disease extend, particularly
the researches into the physiology and chemistry of disease, the
smaller is the area of functional disease. In functional disease there
may be either vague discomfort or actual pain under conditions when
usually such would not be experienced, and on examination no condition
is found which in the vast majority of cases would alone give rise to
that impression on the nervous system which is interpreted as pain. In
the production of the sensations of disease there can be change at any
place along the line, in the sense organs, in the conducting paths or
in the central organ. Thus there may be false visual impressions which
may be due to changes in the retina or in the optic nerve or in the
brain matter to which the nerve is distributed. It is perfectly
possible that substances of an unusual character or an excess or
deficiency of usual substances in the fluids around brain cells may so
change them that such unusual reactions appear. There may be, of
course, very marked individual susceptibility, which may be congenital
or acquired. The perception of every stimulus involves activity of the
nerve cells, and it is possible that the constant repetition of
stimuli of an ordinary character may produce sufficient change to give
rise to unusual reactions, and this particularly when there is lack of
the restoration which repose and sleep bring. We know into what a
condition one's nervous system may be thrown by the incessant noise
attending the erection of a building in the vicinity of one's house or
the pounding of a plumber working within the house, this being
accentuated in the latter case by the thought of impending financial
disaster. Even the confused and disagreeable sound due to the clatter
of high-pitched women's voices at teas and receptions may, when
frequently repeated, be productive of changes in the nerve cells
sufficiently marked to give rise to the unusual reactions which are
evidence of disease.
In the condition known as neurasthenia, which is often taken as a type
of a functional disease, the basal and intrinsic cause is activity of
the nervous system with the using up of material which is not
compensated for by the renewal which comes in repose and sleep.
Neurasthenia is one of the common conditions of our civilization,
found among children and adults, the poor and rich, the idle and the
factory worker; it is rife in the scholastic professions and among
those who earn their living by brain work. It seems to be more common
in the upper classes and particularly in the women, but this is
because these are more subject to medical care and the condition is
more in evidence. There are all sorts of symptoms attached to the
condition, for the unusual mental action can be variously expressed.
The cerebral form has been thus described by a well-known medical
writer: "One of the most characteristic features of cerebral
neurasthenia is a weary brain. The sensation is familiar enough to any
fagged man, especially if he fall short of sleep. Impressions seem to
go half into one's head and there sink into a woolly bed and die.
Voices sound far off, the lines of a book run into one another and the
meaning of them passes unperceived. Doors bang and windows rattle as
they never did before; if a shoestring breaks, an imprecation is upon
the lips. Business matters are in a conspiracy to go wrong. Letters
are left unopened partly from want of will, partly from a senseless
dread lest they contain bad news. At night the patient tosses on his
bed possessed by all the cares which blacken with darkness. Headache
is common, loss of memory is distressing, and in severe cases it is
wider and deeper than mere inattention can explain. There is often the
torture of acute hearing, or an inability to suppress attention; the
hater of clocks and crowing cocks is a neurasthenic." The disease is
especially common in the women players of the social game, and its
unhappy victims too often seek relief from the nervous irritability
which is a common early symptom in still greater nervous excitement.
It is a sad commentary on our civilization that one of the means of
treatment for these persons which has been found efficacious is to
supply them with some restful household occupation such as knitting or
plain sewing, and there are institutions which combine refuge from
social activities, often called duties, with simple occupation.
FOOTNOTE:
[1] By structure as used in this wide sense, there must be
understood not merely the anatomical structure, which is revealed by
the dissecting knife and microscope, but molecular structure, or the
manner in which elements are arranged to form the molecule, as well.