First Book In Physiology And Hygiene Part 13

CHAPTER XXI.

HOW TO KEEP THE MUSCLES HEALTHY.

~1. How to Make the Muscles Strong.~--With which hand can you lift the more? with the right hand or with the left? Why do you think you can lift more with the right hand than with the left? A blacksmith swings a heavy hammer with his right arm, and that arm becomes very large and strong. If we wish our muscles to grow large and strong, so that our bodies will be healthy and vigorous, we must take plenty of exercise.

~2. Effects of Idleness.~--If a boy should carry one hand in his pocket all the time, and use only the other hand and arm, the idle arm would become small and weak, while the other would grow large and strong. Any part of the body which is not used will after a time become weak. Little boys and girls who do not take plenty of exercise are likely to be pale and puny. It is important that we should take the proper amount of exercise every day, just as we take our food and drink every day.

~3. Healthful Exercise.~--Some kinds of play, and almost all kinds of work which children have to do, are good ways of taking exercise. A very good kind of exercise for little boys and girls is that found in running errands or doing ch.o.r.es about the house.

~4. Food and Strength.~--A great part of our food goes to nourish the muscles. Some foods make us strong, while others do not. Plain foods, such as bread, meat, potatoes, and milk, are good for the muscles; but cakes and pies, and things which are not food, such as mustard, pepper, and spices, do not give us strength, and are likely to do us harm.

~5. Over-Exertion.~--We ought not to exert ourselves too much in lifting heavy weights, or trying to do things which are too hard for us.

Sometimes the muscles are permanently injured in this way.

~6. The Clothing.~--We ought not to wear our clothing so tight as to press hard upon any part of the body. If we do, it will cause the muscles of that part to become weak. If the clothing is worn tight about the waist, great mischief is often done. The lungs cannot expand properly, the stomach and liver are pressed out of shape, and the internal organs are crowded out of their proper places.

~7. Tight Shoes.~--People are often made very lame from wearing tight shoes. Their muscles cannot act properly, and their feet grow out of shape.

~8.~ In China, it is fas.h.i.+onable for rich ladies to have small feet, and they tie them up in cloths so that they cannot grow. The foot is squeezed out of shape. Here is a picture of a foot which has been treated in this way. It does not look much like a human foot, does it? A woman who has such feet finds it so difficult to walk that she has to be carried about much of the time. Do you not think it is very wrong and foolish to treat the feet so badly? You will say, "Yes;" but the Chinese woman thinks it is a great deal worse to lace the clothing tight about the body so as to make the waist small.

[Ill.u.s.tration: FOOT OF CHINESE WOMAN.]

~9. Effects of Alcohol upon the Muscles.~--When an intemperate man takes a gla.s.s of strong drink, it makes him feel strong; but when he tries to lift, or to do any kind of hard work, he cannot lift so much nor work so hard as he could have done without the liquor. This is because alcohol poisons the muscles and makes them weak.

~10. Effects of Drunkenness.~--When a man has become addicted to strong drink, his muscles become partly paralyzed, so that he cannot walk as steadily or speak as readily or as clearly as before. His fingers are clumsy, and his movements uncertain. If he is an artist or a jeweller, he cannot do as fine work as when he is sober. When a man gets very drunk, he is for a time completely paralyzed, so that he cannot walk or move, and seems almost like a dead man.

~11.~ If you had a good horse that had carried you a long way in a carriage, and you wanted to travel farther, what would you do if the horse were so tired that he kept stopping in the road? Would you let him rest and give him some water to drink and some nice hay and oats to eat, or would you strike him hard with a whip to make him go faster? If you should whip him he would act as though he were not tired at all, but do you think the whip would make him strong, as rest and hay and oats would?

~12.~ When a tired man takes alcohol, it acts like a whip; it makes every part of the body work faster and harder than it ought to work, and thus wastes the man's strength and makes him weaker, although for a little while his nerves are made stupid, so that he does not know that he is tired and ought to rest.

~13.~ When you grow up to be men and women you will want to have strong muscles. So you must be careful not to give alcohol a chance to injure them. If you never taste it in any form you will be sure to suffer no harm from it.

~14. Effects of Tobacco on the Muscles.~--Boys who smoke cigars or cigarettes, or who chew tobacco, are not likely to grow up to be strong and healthy men. They do not have plump and rosy cheeks and strong muscles like other boys.

~15.~ The evil effect of tobacco upon boys is now so well known that in many countries and in some states of this country laws have been made which do not allow alcohol or tobacco to be sold or given to boys. In Switzerland, if a boy is found smoking upon the streets, he is arrested just as though he had been caught stealing. And is not this really what a boy does when he smokes? He robs his const.i.tution of its vigor, and allows tobacco to steal away from him the strength he will need when he becomes a man.

~16. Tea and Coffee.~--Strong tea and coffee, while by no means so bad as alcohol and tobacco, may make us weak and sick. A person who drinks strong tea or coffee feels less tired while at work than if he had not taken it, but he is more tired afterwards. So you see that tea and coffee are also whips, small whips we might call them, and yet they really act in the same way as do other narcotics and stimulants. They make a person feel stronger than he really is, and thus he is led to use more strength than he can afford to do.

SUMMARY.

1. We must use the muscles to make them grow large and strong.

2. Exercise should be taken regularly.

3. Exercise makes the muscles strong, the body beautiful, the lungs active, the heart vigorous, and the whole body healthy.

4. Things we ought not to do: To run or play hard just before or after eating; to strain our muscles by lifting too heavy weights; to exercise so violently as to get out of breath; to lie, sit, stand, or walk in a cramped position, or awkward manner; to wear the clothing so tight as to press hard upon the muscles.

5. Good food is necessary to make the muscles strong and healthy.

6. Alcohol makes the muscles weak, although at first it makes us feel stronger.

7. A boy who uses tobacco will not grow as strong and well as one who does not.

8. The use of strong tea and coffee may injure the muscles.

CHAPTER XXII.

HOW WE FEEL AND THINK.

~1. How we Think.~--With what part of the body do we think? You will at once say that we think with the head; but we do not think with the whole head. Some parts of the head we use for other purposes, as the mouth to eat and speak with, and the nose to smell and breathe with. The part we think with is inside of the skull, safely placed in a little room at the top and back part of the head. Do you remember the name of this organ which fills the hollow place inside of the skull? We learned some time ago that it is called the _brain_. It is with the brain that we study and remember and reason. So the brain is one of the most important organs in our body, and we must try to learn all we can about it.

~2. The Brain.~--You cannot see and examine your own brain because it is shut up in the skull; but perhaps you can find the brain of a sheep or a calf at the meat market. The brain of one of these animals looks very nearly like your own.

~3. The Large Brain and the Small Brain.~--In examining a brain we should notice first of all that there are really two brains, a _large brain_ and a _small brain_. The large brain is in the top and front of the skull, and the small one lies beneath the back part of the larger one, If we look again we shall see that each brain is divided in the middle into a right and a left half. Each half is, in fact, a complete brain, so that we really have two pairs of brains.

[Ill.u.s.tration: THE BRAIN.]

~4. Brain Cells.~--The brain is a curious organ of a grayish color outside and white inside. It is soft, almost like jelly, and this is why it is placed so carefully in a strong, bony box. If we should put a little piece of the brain under a microscope, we should find that it is made up of a great number of very small objects called _nerve_ or _brain cells_. In the ill.u.s.tration you can see some of these brain cells.

[Ill.u.s.tration: BRAIN CELLS.]

~5. The Nerves.~--Each cell has one or more branches. Some of the branches are joined to the branches of other cells so as to unite the cells together, just as children take hold of one another's hands. Other branches are drawn out very long.

~6.~ The long branches are such slender threads that a great number of them together would not be as large as a fine silk thread. A great many of these fine nerve threads are bound up in little bundles which look like white cords. These are called _nerves_.

~7.~ The nerves branch out from the brain through openings in the skull, and go to every part of the body. Every little muscle fibre, the heart, the stomach, the lungs, the liver, even the bones--all have nerves coming to them from the brain. So you see that the brain is not wholly shut up in the skull, because its cells have slender branches running into all parts of the body; and thus the brain itself is really in every part of the body, though we usually speak of it as being entirely in the skull.

~8. The Spinal Cord.~--There are a number of small holes in the skull through which the nerves pa.s.s out, but most of the nerves are bound up in one large bundle and pa.s.s out through an opening at the back part of the skull and runs downward through a long ca.n.a.l in the backbone. This bundle of nerves forms the _spinal cord_. The spinal cord contains cells also, like those of the brain. It is really a continuation of the brain down through the backbone.

[Ill.u.s.tration: BRAIN AND SPINAL CORD.]

~9. Nerves from the Spinal Cord.~--The spinal cord gives off branches of nerves which go to the arms, the chest, the legs, and other parts. One of the branches which goes to the hand runs along the back side of the arm, pa.s.sing over the elbow. If we happen to strike the elbow against some sharp object, we sometimes. .h.i.t this nerve. When we do so, the under side of the arm and the little finger feel very numb and strange. This is why you call this part of the elbow the "funny" or "crazy bone." The cells of the spinal cord also send out branches to the body and to other cells in the brain.

~10. How we Feel.~--If we cut or burn ourselves we suffer pain. Can you tell why it hurts us to p.r.i.c.k the flesh with a pin, or to pinch or burn or bruise it? It is because the flesh contains a great many nerve-branches from the brain. When we hurt the skin or the flesh, in any way, these nerves are injured. There are so many of these little nerves in the flesh and skin that we cannot put the finest needle into the flesh without hurting some of them.

~11. The Use of Pain.~--It is not pleasant for us to have pain, but if the nerves gave us no pain when we are hurt we might get our limbs burned or frozen and know nothing about it until too late to save them.

~12. Nerves of Feeling.~--We have different kinds of nerves of feeling.