THE LUNGS.
[Illustration: T]HE blood flows all through the body, carrying good food
to every part. It also gathers up from every part the worn-out matter
that can no longer be used. By the time it is ready to be sent back by
the veins, the blood is no longer pure and red. It is dull and bluish in
color, because it is full of impurities.
If you look at the veins in your wrist, you will see that they look
blue.
If all this bad blood goes back to the heart, will the heart have to
pump out bad blood next time? No, for the heart has neighbors very near
at hand, ready to change the bad blood to pure, red blood again.
THE LUNGS.
These neighbors are the lungs. They are in the chest on each side of
the heart. When you breathe, their little air-cells swell out, or
expand, to take in the air. Then they contract again, and the air passes
out through your mouth or nose. The lungs must have plenty of fresh air,
and plenty of room to work in.
[Illustration: _The lungs, heart, and air-passages._]
If your clothes are too tight and the lungs do not have room to expand,
they can not take in so much air as they should. Then the blood can not
be made pure, and the whole body will suffer.
For every good breath of fresh air, the lungs take in, they send out one
of impure air.
In this way, by taking out what is bad, they prepare the blood to go
back to the heart pure and red, and to be pumped out through the body
again.
How the lungs can use the fresh air for doing this good work, you can
not yet understand. By and by, when you are older, you will learn more
about it.
CARE OF THE LUNGS.
Do the lungs ever rest?
You never stop breathing, not even in the night. But if you watch your
own breathing you will notice a little pause between the breaths. Each
pause is a rest. But the lungs are very steady workers, both by night
and by day. The least we can do for them, is to give them fresh air and
plenty of room to work in.
You may say: "We can't give them more room than they have. They are
shut up in our chests."
I have seen people who wore such tight clothes that their lungs did not
have room to take a full breath. If any part of the lungs can not
expand, it will become useless. If your lungs can not take in air enough
to purify the blood, you can not be so well and strong as God intended,
and your life will be shortened.
If some one was sewing for you, you would not think of shutting her up
in a little place where she could not move her hands freely. The lungs
are breathing for you, and need room enough to do their work.
THE AIR.
The lungs breathe out the waste matter that they have taken from the
blood. This waste matter poisons the air. If we should close all the
doors and windows, and the fireplace or opening into the chimney, and
leave not even a crack by which the fresh air could come in, we would
die simply from staying in such a room. The lungs could not do their
work for the blood, and the blood could not do its work for the body.
Impure air-will poison you. You should not breathe it. If your head
aches, and you feel dull and sleepy from being in a close room, a run in
the fresh air will make you feel better.
The good, pure air makes your blood pure; and the blood then flows
quickly through your whole body and refreshes every part.
We must be careful not to stay in close rooms in the day-time, nor sleep
in close rooms at night. We must not keep out the fresh air that our
bodies so much need.
It is better to breathe through the nose than through the mouth. You can
soon learn to do so, if you try to keep your mouth shut when walking or
running.
If you keep the mouth shut and breathe through the nose, the little
hairs on the inside of the nose will catch the dust or other impurities
that are floating in the air, and so save their going to the lungs. You
will get out of breath less quickly when running if you keep your mouth
shut.
DOES ALCOHOL DO ANY HARM TO THE LUNGS?
The little air-cells of the lungs have very delicate muscular (m[)u]s'ku
lar) walls. Every time we breathe, these walls have to move. The muscles
of the chest must also move, as you can all notice in yourselves, as you
breathe.
All this muscular work, as well as that of the stomach and heart, is
directed by the nerves.
You have learned already what alcohol will do to muscles and nerves, so
you are ready to answer for stomach, for heart, and for lungs. Is
alcohol a help to them?
REVIEW QUESTIONS.
1. Besides carrying food all over the body, what
other work does the blood do?
2. Why does the blood in the veins look blue?
3. Where is the blood made pure and red again?
4. Where is it sent, from the lungs?
5. What must the lungs have in order to do this
work?
6. When do the lungs rest?
7. Why should we not wear tight clothes?
8. How does the air in a room become spoiled?
9. How can we keep it fresh and pure?
10. How should we breathe?
11. Why is it better to breathe through the nose
than through the mouth?
12. Why is alcohol not good for the lungs?