Child's Health Primer For Primary Classes Part 3

1. How are the joints moved?

2. Where are the muscles in your arms, which help you to move your elbows?

3. Show why joints must have muscles.

4. What do we call the muscles of the lower animals?

5. What fasten the muscles to the bones?

6. Why do chickens and turkeys need strong muscles in their legs?

7. Why do swallows need strong breast muscles?

8. What makes the muscles of the blacksmith's arm so strong?

9. What will make your muscles strong?

10. What will make them weak?

11. What does alcohol often do to the muscles?

12. Can fatty muscles work well?

13. Why does not drinking beer make one stronger?

CHAPTER III.

NERVES.

[Ill.u.s.tration: H]OW do the muscles know when to move?

You have all seen the telegraph wires, by which messages are sent from one town to another, all over the country.

You are too young to understand how this is done, but you each have something inside of you, by which you are sending messages almost every minute while you are awake.

We will try to learn a little about its wonderful way of working.

In your head is your brain. It is the part of you which thinks.

As you would be very badly off if you could not think, the brain is your most precious part, and you have a strong box made of bone to keep it in.

[Ill.u.s.tration: _Diagram of the nervous system._]

We will call the brain the central telegraph office. Little white cords, called nerves, connect the brain with the rest of the body.

A large cord called the spinal cord, lies safely in a bony case made by the spine, and many nerves branch off from this.

If you put your finger on a hot stove, in an instant a message goes on the nerve telegraph to the brain. It tells that wise thinking part that your finger will burn, if it stays on the stove.

In another instant, the brain sends back a message to the muscles that move that finger, saying: "Contract quickly, bend the joint, and take that poor finger away so that it will not be burned."

You can hardly believe that there was time for all this sending of messages; for as soon as you felt the hot stove, you pulled your finger away. But you really could not have pulled it away, unless the brain had sent word to the muscles to do it.

Now, you know what we mean when we say, "As quick as thought." Surely nothing could be quicker.

You see that the brain has a great deal of work to do, for it has to send so many orders.

There are some muscles which are moving quietly and steadily all the time, though we take no notice of the motion.

You do not have to think about breathing, and yet the muscles work all the time, moving your chest.

If we had to think about it every time we breathed, we should have no time to think of any thing else.

There is one part of the brain that takes care of such work for us. It sends the messages about breathing, and keeps the breathing muscles and many other muscles faithfully at work. It does all this without our needing to know or think about it at all.

Do you begin to see that your body is a busy work-shop, where many kinds of work are being done all day and all night?

Although we lie still and sleep in the night, the breathing must go on, and so must the work of those other organs that never stop until we die.

OTHER WORK OF THE NERVES.

The little white nerve-threads lie smoothly side by side, making small white cords. Each kind of message goes on its own thread, so that the messages need never get mixed or confused.

These nerves are very delicate little messengers. They do all the feeling for the whole body, and by means of them we have many pains and many pleasures.

If there was no nerve in your tooth it could not ache. But if there were no nerves in your mouth and tongue, you could not taste your food.

If there were no nerves in your hands, you might cut them and feel no pain. But you could not feel your mother's soft, warm hand, as she laid it on yours.

One of your first duties is the care of yourselves.

Children may say: "My father and mother take care of me." But even while you are young, there are some ways in which no one can take care of you but yourselves. The older you grow, the more this care will belong to you, and to no one else.

Think of the work all the parts of the body do for us, and how they help us to be well and happy. Certainly the least we can do is to take care of them and keep them in good order.

CARE OF THE BRAIN AND NERVES.

As one part of the brain has to take care of all the rest of the body, and keep every organ at work, of course it can never go to sleep itself.

If it did, the heart would stop pumping, the lungs would leave off breathing, all other work would stop, and the body would be dead.

But there is another part of the brain which does the thinking, and this part needs rest.