How 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.
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.
When you are asleep, you are not thinking,
but you are breathing and other work of the body is
going on.
If the thinking part of the brain
does not have good quiet sleep, it will soon wear
out. A worn-out brain is not easy to repair.
If well cared for, your brain will
do the best of work for you for seventy or eighty
years without complaining.
The nerves are easily tired out, and
they need much rest. They get tired if we do
one thing too long at a time; they are rested by a
change of work.
IS ALCOHOL GOOD FOR THE NERVES AND THE BRAIN?
Think of the wonderful work the brain
is all the time doing for you!
You ought to give it the best of food
to keep it in good working order. Any drink that
contains alcohol is not a food to make one strong;
but is a poison to hurt, and at last to kill.
It injures the brain and nerves so
that they can not work well, and send their messages
properly. That is why the drunkard does not know
what he is about.
Newspapers often tell us about people
setting houses on fire; about men who forgot to turn
the switch, and so wrecked a railroad train; about
men who lay down on the railroad track and were run
over by the cars.
Often these stories end with:
“The person had been drinking.” When
the nerves are put to sleep by alcohol, people become
careless and do not do their work faithfully; sometimes,
they can not even tell the difference between a railroad
track and a place of safety. The brain receives
no message, or the wrong one, and the person does
not know what he is doing.
You may say that all men who drink
liquor do not do such terrible things.
That is true. A little alcohol
is not so bad as a great deal. But even a little
makes the head ache, and hurts the brain and nerves.
A body kept pure and strong is of
great service to its owner. There are people
who are not drunkards, but who often drink a little
liquor. By this means, they slowly poison their
bodies.
When sickness comes upon them, they
are less able to bear it, and less likely to get well
again, than those who have never injured their bodies
with alcohol.
When a sick or wounded man is brought
into the hospital, one of the first questions asked
him by the doctor is: “Do you drink?”
If he answers “Yes!” the
next questions are, “What do you drink?”
and “How much?”
The answers he gives to these questions,
show the doctor what chance the man has of getting
well.
A man who never drinks liquor will
get well, where a drinking man would surely die.
TOBACCO AND THE NERVES.
Why does any one wish to use tobacco?
Because many men say that it helps
them, and makes them feel better.
Shall I tell you how it makes them feel better?
If a man is cold, the tobacco deadens
his nerves so that he does not feel the cold and does
not take pains to make himself warmer.
If a man is tired, or in trouble,
tobacco will not really rest him or help him out of
his trouble.
It only puts his nerves to sleep and
helps him think that he is not tired, and that he
does not need to overcome his troubles.
It puts his nerves to sleep very much
as alcohol does, and helps him to be contented with
what ought not to content him.
A boy who smokes or chews tobacco,
is not so good a scholar as if he did not use the
poison. He can not remember his lessons so well.
Usually, too, he is not so polite,
nor so good a boy as he otherwise would be.
REVIEW QUESTIONS.
1.
How do the muscles know when to move?
2.
What part of you is it that thinks?
3.
What are the nerves?
4.
Where is the spinal cord?
5.
What message goes to the brain when you put
your
finger on a hot stove?
6.
What message comes back from the brain to the
finger?
7.
What is meant by “As quick as thought”?
8.
Name some of the muscles which work without
needing
our thought.
9.
What keeps them at work?
10.
Why do not the nerve messages get mixed and
confused?
11.
Why could you not feel, if you had no nerves?
12.
State some ways in which the nerves give us
pain.
13.
State some ways in which they give us
pleasure.
14.
What part of us has the most work to do?
15.
How must we keep the brain strong and well?
16.
What does alcohol do to the nerves and brain?
17.
Why does not a drunken man know what he is
about?
18.
What causes most of the accidents we read of?
19.
Why could not the man who had been drinking
tell
the difference between a railroad track and a
place
of safety?
20.
How does the frequent drinking of a little
liquor
affect the body?
21.
How does sickness affect people who often
drink
these liquors?
22.
When a man is taken to the hospital, what
questions
does the doctor ask?
23.
What depends upon his answers?
24.
Why do many men use tobacco?
25.
How does it make them feel better?
26.
Does it really help a person who uses it?
27.
Does tobacco help a boy to be a good scholar?
28.
How does it affect his manners?