The Mineral argus., 1884-03-20
THE M HEART.
Useful I~pEorzaattoa About the ETa4rsprins
of Life.

mechanism of the body, the central
,oint in the m~icrocosm, man Its size
$ about equal to that of the closed fist
If the person to whom it belongs. EEs
lverage weight in the adult from twenty
ninety years is, in the male, ter
1unees; in the female, eight tosnine LIZ
,ge il is somewhat larger than in nid-
lie life.
1t is lodged in the chest, between the
Gza vo-y much iGhedded in the
left lung, nearer the front wall Of the
chest than the back, and Is inclosed in
? sort of double bag-the pericardium.
1t is supported by the diaphragm Ito
it is connected by the perlcar-
dunn and by the great vessels which,
from it and entering it, help &c
suspend it and keep it In place.
<'The heart is reallyt two organs united
in one, one half governing the circuIa-
ton through the lungs, the other halt
that of all the rest OK the body. Elk
cept for economy of space and synchro-
nism of action, there might as well have
been two hearts placed in different
parts of the BODY" Each of these
united hearts has two chambers, on
auricle and a ventricle. The muscular
walls of these chambers differ III strength
according to the greater or less force
required of them. 1t is estimated that
the force which effects the contractions
of the left ventricle could move twenty
pounds through the space of on3 foot
in II second of time. Tie right
ventricle is supposed to be about hall
as powerful as the left. Each cavity OF
the heart holds about two ounces, OF
four tablespoonful of blood, Though
double this quantity has been found 10
it after DEATH and as it contracts about
seventy times a minute, more than two
hogsheads of blood traverse it every
hour. Our young readers can easily
estimate how much bloodpasses througs
it in the course of q long life. Substan-
ces injected into the venous blood have
been detected by chemical reaction one
minute afterward in the secretions,
showing that the pulmonary and gen
eral calculations are completed, and Sc
erection or execretion effected IN thus
| small period of time.
Between the chambers Of the right and
left sides of the heart are partitions
that on the right side composedo three
valves, 'the like Of which human lngen
uitv has never invented or initiated,
| that on the left of two. These valves
| omen and close as the blood is forced
through the heart.
The contraction and dilation Of the
two auricles and the two veatgleles are
simultaneous, but the contraction i'll tn
ventricles begins just ~preceptibly afte
that in the auricles. Then comes {
pause or rest, after which the auricle
and ventricles contract again IN til
same order us before, and the
comes a rest. One third of the tim
the heart, that type of unceGsing motion
rests. The striking together of tn
aortic and pulmonary valves at tn
close of the contraction causes n c
the two sounds-the short sound; til
other is supposed by an eminent author
itv to be caused by the friction OF tn
muscular fbles of the heart on eac
other.
An essential part of the nervous SUP
ply of the heart is oentered IN Itself
Nerve centres are situated III the bias
of the organ andin the midst of its othe
structures. 1t also receives branche
from the sympathetic nerve of the lung
and the stomach. If the heart of q lN
ing animal be removed from.its body,
will go on pulsating for a time, as
did {1efore It's removal, showing that til
heart contains within itself, IN part, tn
cause of its Action.
The heartbeat Is caused by the strik
ing of the apex of the heart against tn
pericardium, and through it on the in
ner wall of the chest at the momen
when the Yetricles contract. There /
also a recOil of the whole organ ut thi
moment in obedience to the laws of &C
ton and reaction. The pulse in the ar
teries as felt by the finger does not cor
respond precisely with the beat of th
heart, but takes place a little after u
and the further the artery is from ~
heart the longer is this interval; very
delicate tests prove, however, that tn,
shock of the contraction of the heart
felt all over the muscular system a
once: the actual fluid propelled take
longer to reach and distend the NOR
distant branch.
This organ, at once powerful andd del
icate, is subject to many diseases, som,
of which one may have for a long life
time and not die of at last. Less thar
4 per cent. of all the deaths in Ney
York City are caused by heart-disease
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A father writes to the Pail Mall Ga
] zettn fiat having In Accordance Will