Wilfrid Richmond.

The Americana: a universal reference library, comprising the arts ..., Volume 10 online

. (page 124 of 185)
Online LibraryWilfrid RichmondThe Americana: a universal reference library, comprising the arts ..., Volume 10 → online text (page 124 of 185)
Font size
QR-code for this ebook


port on the International Exhibition of Electri-
city at Paris* (1884), he published: < Ancient
and Modern Light-Houses* (1889); 'Electrical
Appliances of the Present Day* ; < Engineer Ex-
hibit, Centennial Exhibition* (1882); and his-
tory of the Application of Electricity to Light-
ing the Coasts of. France* (1885).

Heard, Franklin Fiske, American jurist:
b. Wayland, Mass., 17 Jan. 1825. He was grad-
uated at Harvard in 1848; was admitted to the
bar in 1850; and practised in Middlesex County
and later in Boston. He attained a reputation
as an authority on pleading, and in 1861-6 was
an editor of the Monthly Law Reporter.* His
publications include: * Libel and Slander*
(1860); an edition of < Stephen on Pleading >
(1867); standard books on < Criminal Pleading 3
(1879) and <Civil Pleading* (1880); <Heard
on Criminal Law* (2d. ed 1882); Shakespeare
as a Lawyer* (1883); < Precedents of Equity
Pleadings* (1884) ; < Precedents of Pleadings
in Personal Actions in the Superior Courts of
Common Law* (1886).

Hearing, one of the five senses, the phys-
ical organ of which is the ear. (See Ear,
Acoustics.)

Heara, hern, David William, American
Roman Catholic clergyman and educator: b.
Boston, Mass., 21 Nov. 1861. He was gradu-
ated at Boston College in 1880; took post-
graduate courses in literature, science and phi-
losophy for five years, and theological courses
for four; entered the Society of Jesus, and
was ordained priest of the Roman Catholic
Church. He was successively professor in
Georgetown University, vice-president of Bos-
ton College, and vice-president of the College of
Saint Francis Xavien New York. In 1900 he
became president of Saint Francis Xavier.



Digitized by



Google



HE ARN — HEART



Hcarn, Lafcadio, American author:* b.
Santa Maura (Leucadia), Ionian Islands, 27
June 1850; d. Tokio, Japan, 26 September 1904.
Educated in England and France, he came to
the United States in 1869, was a journalist
in Cincinnati and New Orleans, in 1887-9 was
at Saint Pierre, Martinique, French West In-
dies, and in 1890 went to Japan. He became
a Japanese subject with the nam* Yakumo
Koizumi, and was appointed lecturer in English
literature at the Imperial University of Tokio.
His ( Stray Leaves from Strange Literature >
(1884), and <Some Chinese Ghosts> (1887),
were succeeded by ( Chita: A Memory of Lost
Island* (1889), story of the destruction of
*L'Ile Derniere? once the watering-place of
Louisiana fashion, which attracted attention
by its descriptive powers; and ( Two Years in
the French West Indies y (i8oo) ? which gained
new interest through the Martinique disaster
of 1002. Among his further works, dealing
almost exclusively with thing9 Japanese and
revealing a thorough comprehension of and
sympathy with the art, myth, tradition, and
philosohy of the Orient, are: ( Out of the
East* (1894); ( Glimpses of Unfamiliar Japan*
(1895); ( Kokovo } (1896); ( Gleanings in
Buddha-Fields> (1897); c Exotics and Retro-
spections* (1898); and ( Kotto, or Japanese
Curios* (1902).

Hearst, Phoebe Apperson, American
philanthropist : b. 1840. Sne was for a time a
teacher, and in 1861 married George F. Hearst
of California. She has been active in charitable
and philanthropic enterprises and has given
largely, especially to educational institutions.
In San Francisco she has established kinder-
garten classes for the children of the poor,
and a manual training school, and has organized
a number of working girl's clubs. She has also
given money to build a National Cathedral
School for girls; has made donations to the
American University at Washington ; has estab-
lished and given largely to public libraries in
the mining towns of the West; and maintained
a school for mining engineers at the University
of California. In 1800 she offered to pay the
expenses of an international competition of
architects to obtain a suitable plan for a campus
«ind buildings for the University of California,
and to erect two buildings in accordance with
this plan. See California, University of.

Hearst, William Randolph, American
newspaper publisher : b. San Francisco. He was
graduated from Harvard, and on leaving college
took charge of the publishing of the San Fran-
cisco Exominer, formerly owned by his father,
Senator Hearst of California. In 1895 he bought
the New York Journal, the name of the morning
edition of which he later changed to the Ameri-
can; in 1900 he started the Chicago American;
in 1004 the Boston American and the Los
Angeles Examiner, In 1002 he presented the
Greek Theatre to the University of California.
He represented the nth Congressional District
<New York) in the 58th and 50th Congresses.
In 1005 ne was defeated for the office of Mayor
of New York City and in 1006 for Governor.

Hearty The. The heart and the blood-
vessels constitute the mechanical means for
maintaining the circulation of the blood. In
many respects this system is the most readily
understood of any in the body, in that it is



largely mechanical. There are, however, certain
factors not existing in an ordinary system of
hydraulics which, while essential to -the proper
performance of the function in the human body,
render the understanding of the subject more
difficult. The heart is merely a pump, or father
two pumps fused, for convenience, into one. It
derives its power through contraction of the red
muscle which forms its wall. It is hollow,
alternately filling and emptying, receiving blood
from one set of tubes filling its cavities, then
emptying its contents into other tubes by contrac-
tion of its walls and momentary obliteration of
its cavities. The action is analagous to that of
the ordinary bulb syringe. The proper direction
of the flow of the blood is maintained by valves,
similar in structure and like in function to the
valves in an ordinary pump.

The heart is about the size of the closed fist.
The average dimensions of the adult organ are :
length 85-00 millimetres in the male, 80-85 mm.
in the female ; breadth, 92-105 mm. in the male,
85-92 mm. in the female; thickness, 35-36 mm.
in the male, 30-35 mm. in the female. The aver-
age weight in men is 300 grams ; in women 250
grams. The heart is cone-shaped with the base
uppermost. It lies within the cavity of the bony
cnest, a small portion of its anterior surface
being in contact with the chest-wall, the rest
covered by the overlapping lungs. The apex of
the cone, or ^apex/ as it is technically called, is
in the space between the fifth and sixth ribs
on the left side, about 2 centimetres to the inside
of a vertical line drawn through the left nipple.
The heart reaches no lower and no farther to
the left than this. From this point it readies
upward to the second rib, two thirds of its mass
being to the left of the middle line of the body.
one third to the right. Its long axis is neither
vertical nor horizontal but is inclined to an angle
of about 30 degrees to the horizontal, hence 60
degrees to the vertical. Therefore it is nearer
horizontal than vertical. The position of the
apex of the heart can be readily determined by
placing the finger in the interspace mentioned
and feeling the beat In the healthy individual
when not under excitement of the emotions or
exercise no motion of the heart can be felt by
the finger upon the chest-wall except at the
apex.

Of secondary importance only to the heart
is the system of tubes conveying the blood:
arteries, capillaries, veins. The arteries are
thick- walled, elastic tubes, dividing and sub-
dividing into k smaller tubes, but the total sec-
tional area increases as the Vessels become
smaller in diameter. These end in a fine net-
work of very small, thin-walled tubes called
from their resemblance in size to hairs, capil-
laries. X nese i" rum become veins, enlarging
their diameter and diminishing their number,
thus reversing the process in the arteries. Veins
have very thin walls in proportion to the
diameter of the bore and are provided with
valves to prevent a back flow of blood.

This arrangement of the blood-vessels may
be likened to two cones, base to base, one apex
representing the largest artery leaving the heart,
the other apex the largest vein entering the
heart, and the bases of the cones the wide capil-
lary system. The flow of blood will be naturally
fastest in the larger arteries and veins, slower
in the smaller arteries and veins, and slowest
in the capillaries, due to the fact alr^dy men-



Digitized by



Google



HEART



tioned that as vessels divide although the
branches are smaller in diameter the combined
sectional area is larger. The condition is quite
like that of the flow of water in a river, the
current being swiftest where the banks approach
each other, slowest where the river widens into
a lake or pond, again to become swifter as the
width of the stream lessens.

The two pumps which compose the heart as
a single whole are called the right heart and left
heart This designation takes its origin from
the fact that one is more to the right side of
the body, the other to the left side. Ordinarily
the two parts are spoken of as the right side and
the left side. The left side is by far the more
powerful pump, having a very thick wall, its
function being to force the blood under consid-
erable pressure through most of the body, the
so-called systemic circulation. The right heart
lias merely to force the blood through the lungs,
a relatively short distance and under low pres-
sure.

Each half of the heart has two cavities, a
thin-walled one called the auricle for receiving
the returning . blood poured into it from the
veins, and a thick-walled one called the ven-
tricle which receives the blood from the auricle
through an orifice guarded by a valve. The
function of the ventricle is to force the blood by
contraction of its muscular wall into the
arteries through a connecting orifice also guarded
by a valve. These four chambers are called the
right auricle, right ventricle, left auricle and left
ventricle. The walls of the auricles are com-
posed of red muscle and are quite thin, the work
required of them being but slight, that is, they
force the blood under slight resistance. The
walls of the ventricles are also made up of red
muscle fibres, the outer surface being smooth,
the inner surface crossed by a network of beams
of muscle called the trabecular The thickness
of the wall of the right ventricle between the
trabecular is from 2 to 3 millimetres ; of the left
ventricle 7 to 10 millimetres. The capacity of
each ventricle is about 100 cubic centimetres,
that is, it forces out about this amount at each
contraction.

The function of the valves is to permit the
flow of liquid in one direction and to prevent
its flow in the opposite direction ; in other words,
their presence enables a pump to maintain a
flow of liquid in one direction with little or no
back flow.

The heart has four valves, one between each
auricle and ventricle, and one in each ventricle
at its point of connection with its outgoing
artery. The valve between the auricle and
ventricle of the left heart is called the mitral,
from its resemblance to a bishop's mitre ; that
between the right auricle and right ventricle is
called the tricuspid from its having three folds
or cusps. The left ventricle is connected with
the systemic circulation by the great artery
called the aorta, its guarding valve is called the
aortic valve. The right ventricle is connected
with the circulation through the lungs by the
pulmonary artery, its valve is called the pul-
monic valve. The aortic and pulmonic valves
are each composed of three cups of thin, flexible
tissue fastened to the inner wall of the blood-
vessel, their edges hanging free, and capacious
enough to meet in the middle of the orifice they
guard. When the ventricles contract, the blood
within them under pressure tends to escape



through any orifice, it presses upon these cups,
forcing them against the walls of the orifice
leading to the aorta and pulmonary artery re-
spectively, leaving an opening of full size. In
other words tliey offer no obstruction to the
flow of blood in this direction. When, however,
the muscle-wall by its contraction has emptied
itself of blood through the orifices just men-
tioned it begins to relax, thus enlarging the
cavity of the ventricle. Were there nothing to
prevent, the blood just forced into the aorta and
pulmonary artery under considerable pressure
would flow back again into the relaxing ven-
tricle, and so it does to a very slight degree, but
this very back flow fills these three cups with
blood, causing them to meet in the middle of the
orifice, thus completely blocking it so far as any
return of blood is concerned, and what blood
has been forced into the aorta and pulmonary
artery remains there to be carried on still fur-
ther with the next contraction of the heart.

The mitral and tricuspid valves are simply
flat folds or curtains attached to the edges of
the orifices between auricles and ventricles.
They are thrown back upon the inner walls of
the ventricles while the blood is flowing from
the auricles into the ventricles, offering little
or no resistance to the flow, but when the flow
of blood is in the opposite direction, that is,
when the ventricles contract, they are floated
upward till the free edges come in contact, thus
blocking the orifice. The flaps are prevented
from going too far by delicate tendinous cords
attached to the free edge of the valves at one
end and to the inside of the heart wall at the
other end. They play the same part that sheets
do for a sail. It will thus be seen that while
one set of valves — mitral and tricuspid — is
closed, the other set — aortic and pulmonic —
will be open, and vice versa.

The period of active contraction of the ven-
tricles is called the systole, and its time is often
spoken of as the systolic period. The period of
dilatation of the ventricles, the time during
which they fill with blood from the auricles, is
called the diastole or diastolic period. In time
the two are nearly equal, the diastole being
somewhat longer.

The cause of the heart beat is a matter of
great interest Inasmuch as the skeletal muscles
require for contraction a stimulus carried to
them through nerves, it was thought that heart
muscle required a similar nerve impulse. It was
known to physiologists that the heart of a frog
severed from its connections went on beating
in spite of there being no nerves attached to it to
convey an impulse from without. Then certain
nerve ganglia were found in portions of the
heart wall and it was inferred that these gave
out the necessary stimulus. But finally it was
found that isolated portions of the heart wall
in which there were no nerve ganglia continued
to beat if they had a blood supply. Hence it was
concluded by Gaskell that the beat of the heart
must be due to an inherent rythmical power of
the ventricle; the stimulus to the muscle prob-
ably residing in some chemical substance in the
blood coming to the part At any rate the
ganglion theory is no longer held, while the
latter is considered the probable one.

The sounds associated with the periods pre-
viously described are readily heard by anyone
placing the ear over the heart of another person,
or with a stethoscope the individual may hear



Digitized by



Google



HEART



his own heart sounds. The contraction of the
ventricles occurs at the time the impulse is seen
and felt over the apex of the heart in the fifth
interspace. It is associated with a booming
sound, loud and distinct. Then comes a short
period of silence corresponding to the time
when the heart muscle ceases its contraction
and begins to relax. Then comes a very short,
sharp, flapping sound due to the closure of the
valves which prevent the return of the blood
from the aorta and pulmonary artery to the ven-
tricles. Then follows a longer period of silence
and again a repetition of the same set of sounds.
The time from the beginning of the first sound
to the beginning of the second sound, that is, the
time of the *boom* and its short silence, is the
systole of the ventricle. The time from the
beginning of the second or short, sharp sound
through the period of silence following it is
the diastole of the ventricle. The whole period
occupied from the beginning of the first of the
sounds described to its repetition is called a
cycle of the heart. Of these there are on an
average in an adult 72 per minute. When the
successive cycles occupy the same length of
time the rhythm is said to be •regular.® When
the times are unequal the term a irregular B is
used. When a beat is dropped the term •inter-
mittent 1 * is applied.

If, when the ear is placed over the heart; the
finger be placed over the artery in the wrist, an
impulse or beat will be felt in the latter, occur-
ring at a slightly later time, about one sixth of
a second, than the apex beat. This is the pulse
wave corresponding to that individual heart
beat. It varies in frequency, in volume and in
tension according to the number of heart beats,
the volume of blood thrown into the arteries
from the heart, and the tension or tone of the
arterial wall. The latter point will be explained
later.

The course of the blood after leaving the
left ventricle is through the aorta and its branch-
ing arteries to the arms and legs and to all the
organs of the body, except the main supply to
the lungs, through capillaries ; thence it is re-
turned by the veins to the right auricle, from
there it goes to the right ventricle, from which
it is pumped through the lungs for purification
to the left auricle and thence to the left ven-
tricle again. The length of time required for
any portion of blood to make the complete cir-
cuit m the human being is not known with abso-
lute accuracy, but it is probably not less than
15 seconds nor more than 30 seconds.

The work done by the heart may be ex-
pressed in units. Assuming the pressure in the
left ventricle during contraction to be 130 milli-
metres of mercury, each square centimetre will
receive a pressure of 175.5 grams. Assuming
further that the left ventricle forces 100 cubic
centimetres of blood at each contraction, the
work done will equal 17,880 gram centimetres.
The right ventricle does a third as much work as
the left, giving a total of 23,840 gram centi-
metres. The total work of the heart per diem
equals 24,000 kilogram metres, equivalent to 56.6
kilo-calories.

The relatively high pressure required of the
heart in maintaining the circulation is due to
the fact that it has to force the blood into
arteries having elastic walls that offer a con-
siderable resistance to stretching. The stream
from the heart into the arteries is intermittent,



the elastic arterial walls are stretched by the
incoming blood absorbing the force during
systole and tending to again give out this force
when the heart ceases during diastole to supply
fresh blood. Even during diastole the pressure
within the arteries remains considerable. Hence
the heart has to force the blood against the
elastic tension of the arterial wall and against
the blood already in the vessel from previous
heart beats. This force stored up in the arterial
wall tends to drive the blood along to the capil-
laries and veins, making in the capillaries and
veins a constant flow, just as a single-cylinder
pump provided with an air-chamber delivers a
constant stream. The circulation, then, in the
arteries is intermittent, in the capillaries and
veins constant.

An element of much interest as well as of
great importance to the proper maintenance of
the circulation in the arteries and to the nutrition
of the organs supplied by them • with blood is
what is called Avascular tonicity,* by which is
meant the peculiar property inherent in the
arterial walls of maintaining a relatively con-
stant blood pressure with varying amounts of
blood contents. In an ordinary system of
hydraulics maintained through elastic tubes the
walls of which are stretched by the circulating
contents, the pressure falls if some of the con-
tents escape. In animals, on the contrary, a con-
siderable quantity of blood may be withdrawn
from the blood-vessels, yet the blood pressure,
after a fall of very short duration, returns to
the normal. This tonicity is due to the fact that
the walls of the arteries have circular muscle
fibres, under control of nerves, that contract
down upon the blood remaining in the vessel
and so maintain the pressure, a matter of great
importance, as an equal pressure in organs is
necessary for the proper physiological function.

The muscle in the arterial walls is supplied
with two sets of nerves called vasomotor nerves,
having opposite actions. One set called vaso-
constrictors has the power when stimulated of
contracting the vessel, the other set called vaso-
dilators enlarges the vessel. Under normal
conditions a certain equilibrium is established
between the two sets of nerves and the artery
is said to possess •tone.* Increased action of
one over the other will produce increased
amount of blood in the part, as m the familiar
example of blushing, or on the other hand pallor
as seen in fright. Certain drugs have a powerful
effect upon these nerves.

Before considering the diseases of the heart
a word may be said of the historical develop-
ment of the subject That the blood circulated
was not known until Harvey demonstrated it in
1628. Auenbrugger, a Viennese physician, in
1 761 invented percussion, the method by which
the position, size, and in a measure the changes
in organs may be determined by the sound pro-
duced when the surface of' the body over them
is struck or •percussed,* as it is technically
called. His invention remained unheeded until
1806, when Corvisart, body physician to Na-
poleon, used it in mapping out the heart m
healthy and in diseased conditions. Laennoc,
the founder of auscultation as used to-day, by
means of his newly invented stethoscope, gave
to the world in 181 9 the first accurate descrip-
tion of the characteristics of the heart sounds
and the significance of changes in the sounds
in the diagnosis of diseases of the heart. Boril-



Digitized by



Google



HEART



laud in France and Hope in England were also
pioneers in this work, practically all that has
been done since then being an elaboration along
lines laid down by them.

By percussion the size and position of the
heart can be accurately determined, and by
auscultation variations from the normal sounds
and the presence of abnormal sounds enable
one to determine what special derangement of
the heart exists.

To understand the abnormalities of the heart
it should be borne in mind that the work of this
organ is done by the muscle of which it is com-
posed ; that the nerve stimulus for the muscular
contraction comes from within the heart wall,
and that the regulatory action, that is, whether
it beats faster or slower, depends upon two
nerves of opposing action, the vagus and the
sympathetic; stimulation of the former slowing
the heart, stimulation of the latter increasing
the rapidity of action. Under ordinary con-
ditions an equilibrium is established between
them, somewhat analagous to the equilibrium in
a balance when equal weights are placed in the
scale-pans; an equilibrium that is at once dis-
turbed if weights are added to or taken from
either pan. Furthermore intact valves are neces-
sary for the proper function of the heart.

Hence changes in the action of the heart are
due to changes in the nerve stimulation ; changes
in the muscle; changes in the valves. They
may exist alone or in combination. Changes
affecting the nerves are more commonly func-
tional or temporary; while those affecting
muscles and valves are organic and usually,
though not always, permanent.

Diseases of the valves are the most frequent,
the most important and of the greatest interest.
A valve to perform its duty properly must be
so flexible that it is readily thrown back against
the walls of the heart so as not to hinder the
passage of the blood through the orifice it
should go. It should also quickly fall back into
place and meet its fellows, so as to block the
passage and prevent the flow of blood in the
direction it should not go. Unfortunately these
delicate valve segments are prone to inflamma-
tion, rheumatic fever being the commonest
cause. This inflammation is associated with the
formation of new tissue much like that formed
in the scar of a wound. It leads to thickening,



Online LibraryWilfrid RichmondThe Americana: a universal reference library, comprising the arts ..., Volume 10 → online text (page 124 of 185)