Albert Franklin Blaisdell.

A practical physiology: a text-book for higher schools online

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which paralyze the inhibitory nerves, with
the others, and at once the uncontrolled
heart, like the unchecked steed, plunges
on to violent and often destructive results.
This action, because it is quicker, has
been considered also a stronger action, and
the alcohol has therefore been supposed to
produce a stimulating effect. But later re-
searches lead to the conclusion that the
effect of alcoholic liquors is not properly
that of a stimulant, but of a narcotic para-
FiG. 80— Two Principal tyrant, and that while it indeed quickens.
Arteries of the Front of it also really weakens the heart's action,
the Leg (Anterior Tibial ^pj^-g ^j^^ ^^^j^ g^^^ Sustained by the fact

and Dorsalis Pedis). , , ... , ,

that the more the intoxicants are pushed,
the deeper are the narcotic and paralyzing effects. After hav-
ing obstructed the nutritive and reparative functions of the vital
fluid for many years, their effects at last may become fatal.



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THE BLOOD AND ITS CIRCULATION. 1 95

This relaxing effect involves not only the heart, but also the
capillary system, as is shown in the complexion of the face
and the color of the hands. In moderate drinkers the face is
only flushed, but in drunkards it is purplish. The flush attend-
ing the early stages of drinking is, of course, not the flush of
health, but an indication of disease.^

198. Effect upon the Heart. This forced overworking of
th^ heart which drives it at a reckless rate, cuts short its periods
of rest and inevitably produces serious heart-exhaustion. If
repeated and continued, it involves grave changes of the struc-
ture of the heart. The heart muscle, endeavoring to compen-
sate for the overexertion, may become much thickened, making
the ventricles smaller, and so fail to do its duty in properly
pumping forward the blood which rushes in from the auricle.
Or the heart wall may by exhaustion become thinner, making
the ventricles much too large, and unable to send on the cur-
rent. In still other cases, the heart degenerates with minute
particles of fat deposited in its structures, and thus loses its
power to propel the nutritive fluid. All three of these con-
ditions involve organic disease of the valves, and all three
often produce fatal results.

199. Effect of Alcohol on the Blood-vessels. Alcoholic
liquors injure not only the heart, but often destroy the blood-
vessels, chiefly the larger arteries, as the arch of the aorta or

1 ^ Alcohol taken in small and single doses, acts almost exclusively on the brain
and the blood-vessels of the brain, whereas taken in large and repeated doses its
chief effects are always nervous effects. The first effects of alcohol on the function
of inhibition are to paralyze the controlling nerves, so that the blood-centers are
dilated, and more blood is let into the brain. In consequence of this flushing of the
brain, its nerve centers are asked to do more work." — Dr. T. S. Clouston, Medical
Superintendent of the Koyal Asylum, Edinburgh.

** Alcoholic drinks prevent the natural changes going on in the blood, and obstruct
the nutritive and reparative functions." — Professor E. L. Youmans, well-known
scientist and author of Class Book of Chemistry,



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196



PRACTICAL PHYSIOLOGY.



the basilar artery of the brain. In the walls of these vessels
may be gradually deposited a morbid product, the result of
disordered nutrition, sometimes chalky, sometimes bony, with

usually a dangerous
dilatation of the tube.

In other cases the .
vessels are weak-
ened by an unnat-
ural fatty deposit.
Though these dis-
ordered conditions
differ somewhat, the
morbid results in all
are the same. The
weakened and stiff-
ened arterial walls
lose the elastic spring
of the pulsing cur-
rent. The blood fails
to sweep on with its
accustomed vigor.
At last, owing per-
haps to the pressure,
against the obstruc-
tion of a clot of
blood, or perhaps to
some unusual strain of work or passion, the enfeebled vessel
bursts, and death speedily ensues from a form of apoplexy.

Note. " An alcoholic heart loses its contractile and resisting power, both through
morbid changes in its nerve ganglia and in its muscle fibers. In typhoid fever,
muscle changes are evidently the cause of the heart-enfeeblement ; while in diph-
theria, disturbances in innervation cause the heart insufficiency. *If the habitual
use of alcohol causes the loss of contractile and resisting power by impairment of
both the nerve ganglia and muscle fibers of the heart, how can it act as a heart
tonic ? ' " — Dr. Alfred L. Loomis, Professor of Medicine in the Medical Depart-
ment of the University of the City of New York.



Fig. 81. — Showing the Carotid Artery and Jugular
Vein on the Right Side, with Some of their Main
Branches. (Some branches of the cervical plexus,
and the hypoglossal nerve are also shown.)



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THE BLOOD AND ITS CIRCULATION. 1 97

200. Other Results from the Use of Intoxicants. Other
disastrous consequences follow the use of intoxicants, and these
upon the blood. When any alcohol is present in the circulation,
its greed for water induces the absorption of moisture from the
red globules of the blood, the oxygen-carriers. In consequence
they contract and harden, thus becoming unable to absorb, as
theretofore, the oxygen in the lungs. Then, in turn, the oxida-



tion of the waste matter in the tissues is prevented ; thus the
corpuscles cannot convey carbon dioxid from the capillaries,
and this fact means that some portion of refuse material, not
being thus changed and eliminated, must remain in the blood,
rendering it impure and unfit for its proper use in nutrition.
Thus, step by step, the use of alcoholics impairs the functions
of the blood corpuscles, perverts nutrition, and slowly poisons
the blood.

Note. " Destroy or paralyze the inhibitory nerve center, and instantly its con-
trolling effect on the heart mechanism is lost, and the accelerating agent, being no
' longer under its normal restraint, runs riot. The heart's action is increased, the pulse
is quickened, an excess of blood is forced into the vessels, and from their becoming
engorged and dilated the face gets flushed, all the usual concomitants of a general
engorgement of the circulation being the result." — Dr. George Harlev, F.R.S.,
an eminent English medical author.



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198 PRACTICAL PHYSIOLOGY.

201. Effect of Tobacco upon the Heart. While tobacco
poisons more or less almost every organ of the body, it is upon
the heart that it works its most serious wrong. Upon this '
most important organ its destructive effect is to depress and
paralyze. Especially does this apply to the young, whose
bodies are not yet knit into the vigor that can brave invasion.

The nicotine of tobacco acts through the nerves that control
the heart's action. Under its baneful influence the motions
of the heart are irregular, now feeble and fluttering, now
thumping with apparently much force : but both these forms
of disturbed action indicate an abnormal condition. Fre-
quently there is severe pain in the heart, often dizziness with
gasping breath, extreme pallor, and fainting.
, The condition of the pulse is a guide to this state of the
heart. In this the physician reads plainly the existence of the
" tobacco heart," an affection as clearly known among medical
men as croup or measles. There are few conditions more dis-
tressing than the constant and impending suffering attending a
tumultuous and fluttering heart. It is stated that one in every
four of tobacco-users is subject, in some degree, to this dis-
turbance. Test examinations of a large number of lads who
had used cigarettes showed that only a very small percentage
escaped cardiac trouble. Of older tobacco-users there are
very few but have some warning of the hazard they invoke.
Generally they suffer more or less from the tobacco heart,
and if the nervous system or the heart be naturally feeble,
they suffer all the more speedily and intensely.

'' The habitual use of alcohol produces a deleterious influence upon the whole
economy. The digestive powers are weakened, the appetite is impaired, and the
muscular system is enfeebled. The blood is impoverished, and nutrition is imperfect
and disordered, as shown by the flabbiness of the skin and muscles, emaciation, or an
abnormal accumulation of fat." — Dr. Austin Flint, Senior, formerly Professor of
the Practice of Medicine in Bellevue Medical College, and author of many standard
medical works.

^* The immoderate use of the strong kind of tobacco, which soldiers affect, is often
very injurious to them, especially to very young soldiers. It renders them nervous



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THE BLOOD AND ITS CIRCULATION. 1 99

and shaky, gives rise to palpitation, and is a factor in the production of the irritable
or so-called " trotting-heart " and tends to impair the appetite and digestion." —
London Lancet,

" I never smoke because I have seen the most efficient proofs of the injurious
effects of tobacco on the nervous system.'' — Dr. Brown-Sequard, the eminent
French physiologist.

"■ Tobacco, and especially cigarettes, being a depressant upon the heart, should be
positively forbidden." — Dr. J. M. Keating, on " Physical Development," in Cyclo-
pcRdia of the Diseases of Children,

ADDITIONAL EXPERIMENTS.

Experiment 93. Touch a few drops of blood fresh from the finger,
with a strip of dry, smooth, neutral litmus paper, highly glazed to prevent
the red corpuscles from penetrating into the test paper. Allow the blood
to remain a short time ; then wash it off with a stream of distilled water,
when a blue spot upon a red or violet ground will be seen, indicating its
alkaline reaction, due chiefly to the sodium phosphate and sodium car-
bonate.

Experiment 94. Place on a glass slide a thin layer of defibrinated
blood ; try to read printed matter through it. This cannot be done.

Experiment 95. To make blood transparent or laky. Place in each of
three test tubes two or three teaspoonf uls of defibrinated blood, obtained
from Experiment 89, labeled A^ By and C. ^ is for comparison. To B
add five volumes of water, and warm slightly, noting the change of color
by reflected and transmitted light. By reflected light it is much darker,
— it looks almost black ; but by transmitted light it is transparent. Test
this by looking at printed matter as in Experiment 94.

Experiment 96. To fifteen or twenty drops of defibrinated blood in a
test tube (labeled D) add five volumes of a lo-per-cent solution of common
salt. It changes to a very bright, florid, brick-red color. Compare its color
with Af By and C. It is opaque.

Experiment 97. Wash away the coloring matter from the twigs (see
Experiment 89) with a stream of water until the fibrin becomes quite white.
It is white, fibrous, and elastic. Stretch some of the fibers to show their
extensibility ; on freeing them, they regain their elasticity.

Experiment 98. Take some of the serum saved from Experiment 88
and note that it does not coagulate spontaneously. Boil a little in a test
tube over a spirit lamp, and the albumen will coagulate.



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200 PRACTICAL PHYSIOLOGY.

Experiment 99. To illustrate in a general way that blood is really a
mass of red bodies which give the red color to the fluid in which they float.
Fill a clean white glass bottle two-thirds full of little red beads, and then fill
the bottle full of water. At a short distance the bottle appears to be filled
with a uniformly red liquid.

Experiment 100. To sho7v how blood holds a mineral substance in solu-
tion. Put an egg-shell crushed fine, into a glass of water made acid by a
teaspoonful of muriatic acid. After an hour or so the egg-shell will dis-
appear, having been dissolved in the acid water. In like manner the blood
holds various minerals in solution.

Experiment loi. To hear the sounds of the heart. Locate the heart
exactly. Note its beat. Borrow a stethoscope from some physician.
Listen to the heart-beat of some friend. Note the sounds of your own
heart in the same way.

Experiment 102. To show how the pulse may be studied. " The move-
ments of the artery in the human
body as the pulse-wave passes
through it may be shown to con-
sist in a sudden dilatation, fol-
lowed by a slow contraction,
interrupted by one or more sec-
ondary dilatations. This dem-
onstration may be made by
pressing a small piece of look-
ing-glass about one centimeter
square (§ of an inch) upon the
wrist over the radial artery, in
such a way that with each pulse
beat the mirror may be slightly
Fig. 83. — How the Pulse may be studied by tilted. If the wrist be now held
Pressing a Mirror over the Radial Artery. in such a position that sunlight

will fall upon the mirror, a spot
of light will be reflected on the opposite side of the room, and its motion
upon the wall will show that the expansion of the artery is a sudden move-
ment, while the subsequent contraction is slow and interrupted." — Bow-
ditch's Hints for Teachers of Physiology.

Experiment 103. To illustrate the effect of muscular exercise in quick-
ening the pulse. Run up and down stairs several times. Count the pulse
both before and after. Note the effect upon the rate.




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THE BLOOD AND ITS CIRCULATION. 20I

Experiment 104. To show the action of the elastic walls of the arteries.
Take a long glass or metal tube of small caliber. Fasten one end to the
faucet of a water-pipe (one in a set bowl preferred) by a very short piece
of rubber tube. Turn the water on and off alternately and rapidly, to imi-
tate the intermittent discharge of the ventricles. The water will flow from
the other end of the rubber pipe in jets, each jet ceasing the moment the
water is shut off.

The experiment will be more successful if the rubber bulb attached to
an ordinary medicine-dropper be removed, and the tapering glass tube be
slipped on to the outer end of the rubber tube attached to the faucet.

Experiment 105. Substitute a piece of rubber tube for the glass tube,
and repeat the preceding experiment. Now it will be found that a continu-
ous stream flows from the tube. The pressure of water stretches the elas-
tic tube, and when the stream is turned off, the rubber recoils on the
water, and the intermittent flow is changed into a continuous stream.

Experiment 106. To illustrate some of the phenomena of circulation.
Take a common rubber bulb syringe, of the Davidson, Household, or any
other standard make. Attach a piece of rubber tube about six or eight
feet long to the delivery end of the syringe.

To represent the resistance made by the capillaries to the flow of blood,
slip the large end of a common glass medicine-dropper into the outer end
of the rubber tube. This dropper has one end tapered to a fine point.

Place the syringe flat, without kinks or bends, on a desk or table.
Press the bulb slowly and regularly. The water is thus pumped into the
tube in an intermittent manner, and yet it is forced out of the tapering end
of the glass tube in a steady flow.

Experiment 107. Take off the tapering glass tube, or, in the place of
one long piece of rubber tube, substitute several pieces of glass tubing
connected together by short pieces of rubber tubes. The obstacle to the
flow has thus been greatly lessened, and the water flows out in intermittent
jets to correspond to the compression of the bulb.



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CHAPTER VIII.
RESPIRATION.

202. Nature and Object of Respiration. The blood, as we
have learned, not only provides material for the growth and
activity of all the tissues of the body, but also serves as a
means of removing from them the products of their activity.
These are waste products, which if allowed to remain, would
impair the health of the tissues. Thus the blood becomes
impoverished both by the addition of waste material, and from
the loss of its nutritive matter.

We have shown, in the preceding chapter, how the blood
carries to the tissues the nourishment it has absorbed from the
food. We have now to consider a new source of nourishment
to the blood, viz,., that which it receives from the oxygen of
the air. We are also to learn one of the methods by which
the blood gets rid of poisonous waste matters. In brief, we
are to study the set of processes known as respiration, by
which oxygen is supplied to the various tissues, and by which
the principal waste matters, or chief products of oxidation,
are removed.

Now, the tissues are continually feeding on the life-giving
oxygen, and at the same time are continually producing car-
bon dioxid and other waste products. In fact, the life of the
tissues is dependent upon a continual succession of oxidations
and deoxidations. When the blood leaves the tissues, it is
poorer in oxygen, is burdened with carbon dioxid, and has had
its color changed from bright scarlet to purple red. This is
the change from the arterial to venous conditions which has
been described in the preceding chapter.



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RESPIRATION. 203

Now, as we have seen, the change from venous to arterial
blood occurs in the capillaries of the lungs, the only means of
communication between the pulmonary arteries and the pul-
monary veins. The blood in the pulmonary capillaries is sep-
arated from the air only by a delicate tissue formed of its own
wall and the pulmonary membrane. Hence a gaseous inter-
change, the essential step in respiration, very readily takes
place between the blood and the air, by which the latter gains
moisture and carbon dioxid, and loses its oxygen. These changes
in the lungs also restore to the dark blood its rosy tint.

The only condition absolutely necessary to the purification
of the blood is an organ having a delicate
membrane, on one side of which is a thin
sheet of blood, while the other side is
in such contact with the air that an inter-
change of gases can readily take place.
The demand for oxygen is, however, so
incessant, and the accumulation of carbon
dioxid is so rapid in every tissue of the
human body, that an All- Wise Creator has
provided a most perfect but complicated
set of machinery to effect this wonderful
purification of the blood.

We are now ready to begin the study Fig. 84.

of the arrangement and working of the res- ^ p^g o ^ •

piratory apparatus. With its consideration, we complete our
view of the sources of supply to the blood, and begin our study
of its purification.

203. The Trachea, or Windpipe. If we look into the mouth
of a friend, or into our own with a mirror, we see at the back
part an arch which is the boundary line of the mouth proper.
There is just behind this a similar limit for the back part of
the nostrils. The funnel-shaped cavity beyond, into which



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204



PRACTICAL PHYSIOLOGY.



both the mouth and the posterior nasal passages open, is
called the pharynx. In its lower part are two openings. ; the
trachea, or windpipe, in front, and the oesophagus behind.
The trachea is surmounted by a box-like structure of carti-
lage, about four and one-
half inches long, called the
larynx. The upper end
of the larynx opens into
the pharynx or throat, and
is provided with a lid, —
the epiglottis, — which
closes under certain cir-
cumstances (sees. 137 and
349). The larynx contains
the organ of voice, and is
more fully described in
Chapter XII.

The continuation of the
larynx is the trachea, a
tube about three-fourths of
an inch in diameter, and
about four inches long.
It extends downwards
along the middle line of
the neck, where it may
readily be felt in front,
below the Adam's apple.

The walls of the wind-
pipe are strengthened by
a series of cartilaginous
rings, each somewhat the shape of a horseshoe or like the letter
C, being incomplete behind, where they come in contact with
the oesophagus. Thus the trachea, while always open for the
passage of air, admits of the distention of the food-passage.



Fig. 85. — Larynx, Trachea, and the Bronchi.
(Front view.)

A, epiglottis ; B, thyroid cartilage ; C, cricoid-
thyroid membrane, connecting with the cricoid
cartilage below, all forming the larynx ; D, one
of the rings of the trachea.



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RESPIRATION. 205

204. The Bronchial Tubes. The lower end of the wind-
pipe is just behind the upper part of the sternum, and there it
divides into two branches, called bronchi. Each branch enters
the lung of its own side, and breaks up into a great number of



Fig. 86. — Relative Position of the Lungs, Heart, and its Great Vessels.

A, left ventricle ; B, right ventricle; C, left auricle; D, right auricle; E, superior vena
cava; F, pulmonary artery ; G, aorta; H, arch of the aorta; K, innominate artery ;
L, right common carotid artery; M, right subclavian artery; N, thyroid cartilage
forming upper portion of the larynx ; O, trachea.

smaller branches, called bronchial tubes. These divide into
smaller tubes, which continue subdividing till the whole lung
is penetrated by the branches, the extremities of which are
extremely minute. To all these branches the general name of
bronchial tubes is given. The smallest are only about one-
fiftieth of an inch in diameter.



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206 PRACTICAL PHYSIOLOGY.

Now the walls of the windpipe, and of the larger bronchial
tubes would readily collapse, and close the passage for air,
but for a wise precaution. The horseshoe-shaped rings of car-
tilage in the trachea and the plates of cartilage in the bronchial
tubes keep these passages open. Again, these air passages have
elastic fibers running the length of the tubes, which allow them
to stretch and bend readily with the movements of the neck.

205. The Cilia of the Air Passages. The inner surfaces
of the windpipe and bronchial tubes are lined with mucous

membrane, continuous with that of
the throat, the mouth, and the nostrils,
the secretion from which serves to
keep the parts moist.

Delicate, hair-like filaments, not un-
like the pile on velvet, called cilia,
spring from the epithelial lining of
the air tubes. Their constant wavy
movement is always upwards and out-
wards, towards the mouth. Thus any
excessive secretion, as of bronchitis
or catarrh, is carried upwards, and
finally expelled by coughing. In this

F,G. 87.- Bronchial tube, with ^^y- ^^« .'""^s ate kept quite free
its Divisions and Subdivisions, ^^om particles of foreign matter de-
(Showing groups of air cells at rived from the air. Otherwise we

theterminationof minutebron- ^^^^^^ ^^^ ^^^ ^^^^^ ^^ .^^ ^^
chial tubes.) ' ^

from the accumulation of mucus and
dust in the air passages. Thus these tiny cilia act as dusters
which Nature uses to keep the air tubes free and clean (Fig. 5).

206. The Lungs. The lungs, the organs of respiration,
are two pinkish gray structures of a light, spongy appearance,
that fill the chest cavity, except the space taken up by the
heart and large vessels. Between the lungs are situated



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RESPIRATION. 20/

the large bronchi, the oesophagus, the heart in its pericardium,
and the great blood-vessels. The base of the lungs rests on
the dome-like diaphragm, which separates the chest from the
abdomen. This partly muscular and partly tendinous partition
is a most important
factor in breathing.
Each lung is
covered, except at
one point, with an
elastic serous mem-
brane in a double
layer, called the
pleura. One layer
closely envelops the
lung, at the apex of
which it is reflected
to the wall of the
chest cavity of its

own side, which it FiG.g8._xhe Lungs with the Trachea, Bronchi, and

lines. The two layers Larger Bronchial Tubes exposed. (Posterior view.)

thus form between a, division of left bronchus to upper lobe ; B, left branch

them a closed sac a o^ the pulmonary artery; C, left bronchus; D, left superior

* pulmonary vein ; E, left inferior pulmonary vein ; F, left

serous cavity (see auncle; K, inferior vena cava; L, division of right bronchus

Fio" fin aKn nnfp to lower lobe; M, right Inferior pulmonary vein; N, right

o* y» > superior pulmonary vein ; O, right branch of the pulmon-

p. 176). ary artery; P, division of right bronchus to upper lobe;

In health the two . ^' ^^^' ^^°'"^^^ ' ^' "«^' ^""*"^^^-
pleural surfaces of the lungs are always in contact, and they
secrete just enough serous fluid to allow the surfaces to glide
smoothly upon each other. Inflammation of this membrane is
called pleurisy. In this disease the breathing becomes very
painful, as the secretion of glairy serum is suspended, and the



Online LibraryAlbert Franklin BlaisdellA practical physiology: a text-book for higher schools → online text (page 16 of 36)