Читать книгу How to live: A manual of hygiene for use in the schools of the Philippine islands - Adeline Knapp - Страница 3

CHAPTER I.
THE HUMAN BODY.

Table of Contents

In America, where they make the best locomotive engines in the world, they say that the life of an engine is about twenty years. That is, when they build an engine, they know about how much work it will have to do and what usage it is likely to have. They know that the engine is strong enough to do such work and stand such usage for twenty years. So they say that the length of the engine’s life is twenty years.

Now, a man’s body is, in its way, a machine. It is made to do certain work, and if it has the right sort of care, it ought to be healthy and do the work required of it, to the end of the man’s life. It is estimated that the natural life of a man is seventy years. This little book is intended to tell us how to live and something about caring for our bodies so that they shall last as long as possible, and be ready and able to do their work in the world.

The Skull, Chest, and Abdomen.

In a general way, we may compare the human body to three closed boxes, one above another. These boxes are the skull, the chest, and the abdomen. Each one has its own special contents, formed to do a special work for the body. The skull is a hard, bony case made to contain the brain. This is where the mind lives, and it is part of the work of the mind to take care of the body and direct its movements. The brain maintains a sort of telegraph station within itself. Wires, which we call nerves, branch out from it to all parts of the body, and the brain is constantly receiving messages over these wires and sending others telling the muscles what to do. For instance, if the hand comes in contact with something hot, a message instantly goes to the brain, telling this fact. The brain sends back word to take the hand away, and the hand is withdrawn. But all this is done so quickly that the hand seems to be withdrawn the very instant that it comes in contact with the fire. The skull is supported by the backbone, which connects it with the second closed box.

This second cavity is the chest, which is really a sort of cage formed by the ribs, the backbone, and the breastbone. In the chest are the heart and the lungs. The heart is an engine. Put your hand over it and you can feel the steady throb of its beat, day and night. It is working all the time, whether you are awake or asleep. The business of the heart is to send blood to all parts of the body. It does this by driving the blood through tubes, called arteries and veins, that go all over the body. The arteries are deep down among the muscles, but some of the veins are close to the surface. We can see blue veins at the temples and on the backs of our hands. All the blood goes to every part of the body once in two minutes.

The food which a person eats is acted upon by the digestive fluids in the body and is turned over and dissolved until it becomes fluid itself. It is then taken up by the blood and carried to different parts of the body, so that each organ and muscle gets what it needs. We shall learn, a little later, just how the food gets into the blood. We have seen that the heart sends the blood out through vessels, which are called arteries. This blood starts from the heart bright red, full of fresh air and food for the body. As it goes on its journey, each tissue takes from it what is needed to keep that part healthy, and at last the blood has given out all the good things with which it was loaded. It no longer carries food and fresh air, but is full of the impurities taken in on its journey. If something were not done to cleanse it, the man would die.

The Circulation of the Blood.

The blood is forced by the heart through the arteries (black lines), and returns to it through the veins (dotted lines).

The impure blood flows from the arteries into the veins through tiny canals. The veins are tubes something like the arteries, and they usually lie beside the arteries. They and the arteries are like the two tracks of a great railway line, one going from the main station, the heart, the other coming back.

But the blood in the veins is not like that in the arteries. Instead of being bright red, and healthy-looking, it is dark colored. It flows more slowly, and it is full of impurities which it is carrying away from the body. The veins carry this blood to the right side of the heart, and the heart sends it to the lungs. There are many blood vessels in the lungs, and they are divided into branches running in every direction through the lung tissue. When we draw in a deep breath, we fill the lungs with fresh air. This is at once taken up by the impure blood in the branching blood vessels. The impurities are breathed out with the air that leaves our lungs, and the blood once more becomes bright red and full of new life. In this way the blood is purified. Then it is sent back to the heart, all ready to start out again through the body. The whole journey is made every two minutes.

The third box, which we call the abdominal cavity, is separated from the chest by a broad, thin muscle, the diaphragm. The abdomen has a hard floor of bone, but the walls are soft, being made up only of the muscles and the lower ribs. In the abdomen are the stomach and intestines, the liver, kidneys, and other organs of which we shall learn later.

Food is carried from the mouth to the stomach by the muscular tube which passes through the chest just back of the breastbone. This tube is called the esophagus. With the mouth, the stomach, and the bowels, it forms what is called the food canal.

As soon as the food enters the mouth, it begins to turn from solid into liquid form, so that the blood can take it up. We chew the food, so that it may become mixed with the saliva in the mouth; then it is swallowed and goes into the stomach. This is a kind of sack which holds about a quart. Just as saliva is secreted in the mouth and acts upon the food, so in the stomach there is a fluid called the gastric juice, which aids digestion. The gastric juice mixes with the food, dissolves it, and makes it soft, so that it can pass through the lower opening of the stomach into the intestines. Here there are other juices which dissolve still more of the food, until at last it is all liquid and looks like milk.

Now it is taken up by the blood through tiny canals that reach down into the intestines and absorb it. But it is not really a part of the blood yet. It must be changed still further, so the blood carries it to the liver. Here it is made a part of the blood, and is able to nourish all parts of the body.

All the food that cannot be dissolved is indigestible, and the body must get rid of it. Some of it passes off as solid matter, by way of the bowels; some is got rid of through the urine; some goes out with the breath, as we have seen; and a great deal goes off in the perspiration. This is why we need to bathe our bodies and to wash our clothing. The perspiration brings the bad matter to the surface, where it clings to the skin and the clothing until it is removed by washing.

But this series of boxes, which we call the head and trunk of the body, would be very helpless without the legs and arms to carry them about and to wait upon them. Taken all together, the head, trunk, and limbs form the body. The framework, which we call the skeleton, is made up of bones. These bones are like the framework of a house,—they keep the body upright and support the muscles. In young people the bones are soft and elastic. A baby often has falls that would break the bones of a grown person, but the baby’s bones are not broken because they are not yet hardened. This is an advantage, for children get a great many more falls than grown people do, and it would be hard for them if the bones were broken as easily.

But if children’s bones do not break, they bend, and it is easy for them to grow into bad shape. If children do not sit up straight they become round-shouldered, and many children get into the habit of carrying one shoulder higher than the other. Often, too, they are careless about walking and sitting properly.

The Wrong Way to Carry a Baby.

In this country, where nearly all weights are carried on the head, we rarely see a man who does not carry his head and shoulders well. He learns in childhood to keep his shoulders even and to hold his head up. But there is one custom of the country which prevents the people from walking well. This is the practice of carrying little children on the hip. It is bad for the children, as it strains the muscles of the lower part of the back, and bends the soft little bones so that they do not grow straight as they naturally would. It is bad, too, for the person who carries the child. The body is thrown to one side, the weight of the child presses the soft organs of the abdomen downward, and the effect is often serious. It is very bad indeed for one child to carry another this way. Babies should be carried in the arms, as European children are.

When we walk, we should let the weight of the body rest on the soles of the feet. We should lift the foot free from the ground and carry it straight forward when we step. Some day, if you will study the difference between the walk of a good horse and that of a carabao, you will see how a man should walk. The horse lifts his hind foot, carries it straight forward, and sets it down almost exactly in the print his front foot made. The carabao lifts his hind foot, swings it outward in an awkward curve, brings it back into line, and sets it down in much the same way as the horse. But he loses a little time swinging it outward, and he looks very clumsy, as well.

Now, some people, instead of walking like horses, walk like carabaos. They scuffle along the street with dragging steps, rolling their hips, and swinging their feet outward, just as these animals do. They look lazy and clumsy, and as if they could hardly hold their bodies together. People should learn to walk well while they are young.

The bones are covered with muscles, which are what we mean when we say the flesh. There are a great many muscles in the body. They give it shape and move it about. When we bend an arm or a finger, we do it by the action of the muscles. The brain tells the muscles how to act, as we have seen. It sends messages along the nerves, and the muscles obey. We can make our muscles strong by exercise, but if we do not use them enough, they will grow weak and soft.

QUESTIONS.

Table of Contents

How does the brain send messages to the different parts of the body?

What does the heart do?

What does the blood take up from the body?

How does it get rid of impurities?

What becomes of food after it is swallowed?

How are the bones of a child different from those of a grown person?

How does it hurt the bones to sit or stand badly?

Why should we sit up straight?

How ought babies to be carried?

Why is it hurtful to carry them on the hip?

What do we call the muscles?

What are their uses?

How can we make our muscles strong?