MY
BODY TEMPLE
PART 7
Your
Heart
If
you place your hand on the left side of your chest, you will feel
something beating. If you cannot feel the beats easily, run up and
down stairs two or three times, and you will feel them distinctly.
What is this curious machine inside the chest, that beats so
steadily? It is the heart.
The
heart may be called a live pump, which keeps pumping away during our
whole lives. If it should stop, even for a minute or two, we would
die. If you place your hand over your heart and count the beats for
exactly one minute, you will find that it beats about seventy-five or
eighty times. When you are older, your heart will beat a little more
slowly. If you count the beats while you are lying down, you will find
that the heart beats more slowly than when you are sitting or
standing. When we run or jump, the heart beats harder and faster.
Why
does the Heart Beat? We have learned in preceding lessons that the
digested food is taken into the blood. We have also learned that both
water and oxygen are taken into the blood. Thus the blood contains all
the materials that are needed by the various parts of the body. But if
the blood were all in one place it could do little good, as the new
materials are needed in every part of the body. God has provided a
wonderful system of tubes running through every part of the body.
These tubes carry the blood into every part. They are connected with
the heart. When the heart beats, it forces the blood through the tubes
just as water is forced through a pipe by a pump or a fire-engine.
The
heart has four chambers, two upper and two lower chambers. The blood
is received into the upper chambers, called the atrium, and is then
passed down into the lower chambers called ventricles. From the
ventricles it is sent out to various parts of the body.
The
heart tubes through which the blood is carried are called blood
vessels. There are three kinds of blood vessels. One set carry the
blood away from the heart, and are called arteries (ar' te-ries).
Another set return the blood to the heart and are called veins. The
arteries and veins are connected at the ends farthest from the heart
by many very small vessels. These minute, hairlike vessels are
called capillaries (cap' -il-Ia-ries).
An
artery leads out from the lower chamber of each side of the heart. The
one from the right side of the heart carries the blood only to the
lungs. The one from the left side of the heart carries blood to every
part of the body. It is the largest artery in the body, and is called
the aorta. Soon after it leaves the heart the aorta begins to send out
branches to various organs. These divide in the tissues again and
again until they become so small that only one corpuscle can pass
through at a time.
These
very small vessels now begin to unite and form larger ones, called
veins. The small veins join to form larger ones, until finally, all
connect into two large veins which empty into the upper chamber of the
right side of the heart. The veins which carry blood from the lungs to
the heart empty into the upper chamber of the left side of the
heart.
MY BODY
TEMPLE
PART 8
A
Drop of Blood
Did
you ever cut or prick your finger so as to make it bleed? Probably you
have more than once met with an accident of this sort. All parts of
the body contain blood. If the skin is broken in any place the blood
flows out.
Do
you know what a microscope is? It is an instrument, which magnifies
objects, or makes them look a great deal larger than they really are.
Some microscopes are so powerful that they will make a little speck of
dust look as large as a great rock.
If
you should look at a tiny drop of blood through such a microscope,
you would find it to be full of very small, round objects called blood
corpuscles. They look something like little red donuts but they
don’t have holes.
You
would notice that there are two kinds of corpuscles. Most of them are
slightly reddish, and give to the blood its red color. A very few are
white.
Do
you wonder what these little corpuscles do in the body? They are very
necessary. We could not live a moment without them. We need to take
into our bodies oxygen from the air. It is the business of the red
corpuscles to take up the oxygen in the lungs and carry it round
through the body in a wonderful way, of which we shall learn more in a
future lesson.
The
white corpuscles have something to do with keeping the body well. They
are carried by the blood into all parts of the body and stop where
they find a foreign object, something that is not part of the body.
This may be a virus, bacteria, or it may be something like a sliver!
The white corpuscles go to work fighting this foreign object to
prevent infection and sickness. If it is a germ, the white corpuscles
gobble it up!
The
corpuscles float in clear, almost colorless fluid, called plasma,
which contains the digested food and other elements by which the body
is nourished.
A
severe loss of blood, called a Hemorrhage (hem'-or-rhage) can happen
from accidents or injuries of various sorts. It is important to know
what to do quickly, as there may not be time to get to hospital fast
enough to save the injured person's life. Here are a few pointers:
If
the blood from a cut flows in spurts and is bright red, it is from an
artery. If it is dark-colored, and flows in a steady stream, it is
from a vein.
It
is best to apply pressure directly over the wound. The pressure can be
made with the thumbs or with the whole hand. Grasp the part firmly and
press very hard, or tie a handkerchief or towel around the wounded
part and twist it tight. If the cut is on an arm or leg, have the
person lie down, and hold up the injured part. This is an excellent
means of stopping hemorrhage.
Nosebleeds
may be stopped by placing the hands and feet into very warm water. At
the same time place an ice-pack on the back of the neck. Often the
ice-pack alone will do the trick. Keep the head up and a bit forward
to prevent choking. =^..^=
MY BODY
TEMPLE
PART 9
Circulation
While
the blood is passing through the small blood vessels in the various
parts of the body, each part takes out just what it needs to build up
its own tissues. At the same time, the tissues give out their worn-out
or waste matters. The red blood cells (corpuscles) in the capillaries
give up their oxygen, and the blood receives in its stead a poisonous
substance called carbon-dioxide.
While
in the arteries the blood is of a bright red color; but while it is
passing through the capillaries the color changes to a bluish red, or
purple, color. The red blood is called arterial blood, because it is
found in the arteries. The purple blood is called venous blood,
because it is found in the veins. The loss of oxygen in the cells
causes the change of color.
Exactly
the opposite happens in the blood when it passes through the lungs.
The blood, which has been gathered from the various parts of the body,
is dark, impure blood. In the lungs this dark blood is spread out in
very tiny capillaries and exposed to the air.
While
passing through the capillaries of the lungs, the blood gives up some
of its impurities in exchange for oxygen from the air. The red cells
absorb the oxygen and the color of the blood changes from dark purple
to bright red again. The purified blood is then carried back to the
upper chamber of the left side of the heart through four large veins.
The blood is now ready to begin another journey around the body.
If
you place your finger on your wrist at just the right spot, you can
feel a slight beating. This beating is called the pulse. It is caused
by the movement of the blood in the artery of the wrist at each beat
of the heart. The pulse can be felt at the neck and in other parts of
the body where an artery comes near to the surface.
The
heart is a small organ, only about as large as your fist, and yet it
does an amazing amount of work. Each time it beats, it does as much
work as your arm would do in lifting a large apple from the ground to
your mouth. It beats when we are asleep as well as when we are awake.
When we run it beats very fast. A ton is 2,000 pounds; in twenty-four
hours the heart does as much work as a man would do in lifting stones
enough to weigh more than one hundred and twenty tons.
While
the blood is passing through the capillaries, some of the white cells
escape from the blood vessels. What do you suppose becomes of these
runaway cells? Nature has provided a way by which they can get back
to the heart. In the little spaces among the tissues outside of the
blood vessels very tiny channels called lymph channels or lymphatics (lym-phat'-ics)
begin. The whole body is filled with these small channels, which run
together like a net. In the center of the body the small lymphatics
run into large ones, which empty into the veins near the heart. This
is how the stray white blood cells get back into the blood.
In
the lymph channels the white cells float in a colorless fluid called
lymph. The lymph is plasma from the blood, which has soaked through
the walls of the small vessels. The chief purpose of the lymphatics is
to carry the lymph from the tissues back to the heart.
Here
and there, scattered through the body, are oval structures where many
lymphatic vessels connect. These are called lymph nodes. In these
germs and foreign matter are trapped and eaten up by the white blood
cells. The heart and blood vessels are among the most wonderful
structures in the body. =^..^=
 
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