The Lambertville record. [volume] (Lambertville, N.J.) 1872-1968, 1879-06-11

two fiat cords stretching across It, and the air
comes out between them. When the air Is
forced out from the lungs it strikes on these
cords, and sound Is made, just as when the
key of an organ is struck while the pedals are
in motion, a sound is produced, by the air
from the bellows striking on the reed The
chest may represent the bellows to this little
organ In the throat. The air is passing out
and in through the chink between the cords
of the larynx continually as we breathe. But
it does not, as you know, always produce d
sound. When the cords are loose they do not
make any sound. They are loose when we
merely breathe but when we speak or sing,
they are frightened The strings of violin
viii give no sound unless they are stretched
| tight SO It is with the cords of the larynx. -
There are little muscles that tighten the cords
of this organ when it is required. When we
merely breathe these muscles do not act. But
when we speak they contract, and thus tight.
en- the cords. The different notes of the voice
depend upon the degree to which these cords
are frightened. When the note is a high one,
they are very tense I; but when the note is a
low one, they are but slightly tense. The
working of these little muscles in tightening
these cords is regulated by the mind in the
brain, by means of the nerves that go to them.
The lungs are essentially the seat of the
process of respiration, and occupy nearly the
whole cavity Of the chest or thorax. They
are two bodies of graysh pink color, sepa-
rated by the heart and its great vessels. They
are spongy and full of very small airscells,
which give them their spongy lightness ; and
as q sponge is much larger when it's cells are
filled with water than when it is dry, so the
lungs swell outwhen theircells are filed with
air. 1t is in these airscells that the air chang
es the dark blood to red. But this is not done
by mixing up the blood with the air of these
cells. The blood is never mixed with the air,
except, when in disease, blood is raised from
the lungs. In such a case, the blood gets in
TO the air. cells and air tubes. But in health
this will never happen. The thin skin or
membrane, that makes each air.eell, will not
let the blood come through 1t. The air acts
upon the blood through the pores of this
membrane, and the capllaries that branch ont
upon it. 1t is by the oxygen of the air we
take in at every inspiration, that every drop
of dark blood that goes to the lungs is chang
ed to red blood. HH- fa
The great object Of this respiratory appa.
ratue is to keep the air going into and out of
these air-cells In this way. fresh air is con-
tinually brought to the blood. When we
breathe in or inspire, the air is forced into all
thaca coils md ~ hon ,y., hraotl,o
pire, 1t is forced out of them. But it is not
all forced out. The lungs are never entirely
empty Of air. Enough is forced out to keep
the air in the lungs constantly changing. -
The average number of respiratinns made in
a minute is about eighteen taking in and
dscharging about twenty cubic inches of air
at each respiratory movement. 1t is the mus
Giles Of the chest that perform the movements
of respiration. The principal muscle that
acls in these movements is the diaphragm. 1t
is a stout muscular aud tendinous sheet.
stretching across the lower part of the chest.
1t serves as partition between the cavity Of
the chest aud the cavity of the abdomen.
Above it are the heart and lungs, below it are
the stomach, liver, ntestines, &c.
The right lung is divided into three lobes,
and the left two. SO you learn that the right
lung is the largest, both in size and weight
weighing about two ounces more than the left.
The entire weight Of both lungs together, is
about forty two ounces /; a little over two
pounds and half. But this is subject to
much variation according 10 the amount of
blood or Serious fluid they may contain. The
right lung is broader than the left, owing to
the inclination of the heart tn the left side,
and is also shorter by an inch, In consequence
of the diaphragm rising higher on the right
side To accommodate the liver.
Thus have given the frame work or skel-
eton, the Enclosure or muscular system, the
lines of communication or nervous system,
the apparatus for distributing the blood or
circulatory system, and the pneumatic appa-
ratus for changing the blood from dark or VEN
Gus to red Or arterial, (by discharging the
carbonic acid gas from tho venous, and taking
ON oxygen gas instead, thus changing it to
red or arterial blood, called the respiratory
system. l will next give the structure and
functions of the digestive system, and the
organs OF special sense.
FRO BE coNTINUED.)