THE HUMAN BODY AND THE GREAT LAWS OF HEALTH

A GREAT engine is made of many different parts all put together to make one machine. So is the human body made of many different parts all joined together to make one whole. The engineer must know when his engine needs coal and water and how to supply them. So we must understand the needs of our bodies and how to satisfy these needs. The engineer must know how to keep sand and dirt out of the working parts of the engine and how to oil these parts so that they will not wear each other away. So we must know how to keep out of our bodies the germs that cause disease and how to give our bodies the exercise and rest that are necessary for their health. In this chapter we shall study the parts of the body, the needs of the body, and the great laws we must observe to keep our bodies in health.

The parts of the human body. The human body is composed of a head, a trunk, and two pairs of limbs. It is supported by a strong framework of bones on which the whole body is built. The muscles to move this framework of bones are stretched over it in strong bands, and the skin forms a tough covering over the whole body.

The organs of the body. The bones and muscles form a thick wall about a large cavity in the trunk of the body. In this cavity are found

many of the organs that do the work of the body. In the upper part of the cavity we find the heart and lungs. In its lower part are the stomach, the

FIG. 3. The principal organs of the body. The left lung has been removed and the edge of the right lung turned back to show the heart and blood vessels more clearly.

intestines, the liver, the kidneys, and some other organs. In Figure 3 the organs are shown as they lie in place in the cavity of the trunk.

The uses of the organs. Each part of the body has a work to do. The bones give shape and strength to every part. Without them we should be as limp and shapeless as bags of sand. The muscles move all the body parts, and without the muscles we should be as motionless as trees or stones. The stomach and intestines receive food and prepare it for use; the heart keeps the blood moving through the body; and the lungs take in oxygen from the air. The hand has a work that the foot can

not do, and the eye has a work that the tongue cannot do. In the same way each part of the body has a work of its own that can be done by no other part.

The great laws of health. For an engineer to understand the importance of taking care of his engine is not enough; he must also know how to do it. So, if we hope to have strong, healthy bodies, we must not only understand the importance of keeping the laws of health, but we must know what these laws are and how we can keep them. The following are the great laws of health that we should understand and observe:

1. The body must have a proper supply of food. 2. It must have an abundance of fresh air. 3. It must get rid of its poisonous wastes. 4. It must be sheltered from the weather so that it will not be too hot or too cold.

5. It must have exercise, rest, and sleep. 6. It must be kept free from pain.

7. The mind must be cheerful, and not disturbed by constant fretting, anxiety, or care.

8. Disease germs must not be allowed to get into the body and poison it.

Every one of these laws must be followed if we are to keep our health and our strength; for as a lily in the garden flourishes when it has a fertile soil and other favorable conditions, so will your body have strength and vigor if its needs are satis

fied and it is allowed to live in accordance with the laws of health. And as surely as the lily wilts when its food or its supply of water fails, so surely must your body be injured if you break the great laws of its life. In later chapters of this book we shall discuss each of these laws and point out how each may best be followed.

Questions: 1. Name the principal divisions of the body. 2. What forms the framework of the body? 3. What is stretched over the framework of the body to move it? 4. With what is the body covered? 5. What organs are in the upper part of the cavity of the body? 6. In the lower part? 7. What is the work of the bones? 8. Of the muscles? 9. Of the stomach and intestines? 10. Of the heart? 11. Of the lungs? 12. Name some other organs of the body and tell what they do. 13. Give some of the great laws of health. 14. What will happen to us if we keep these laws? 15. If we break them?

Suggestions and topics for development: When any one is absent from the school or grade on account of illness, let the teacher and pupils discuss the cause of the illness and whether it could have been prevented by reasonable care. Keep a record of all cases and at the end of the year find how many days have been lost on account of illness and how much of this illness might have been prevented. Keep developing the idea that health follows right living, and that each pupil is hygienically the architect of his own fate.