Principles of Public Health. Thomas Dyer Tuttle
they can be seen only with a powerful microscope. If you look at your hand you cannot see a cell, because it takes a great many cells to make a spot large enough for you to see. In Figure 1 you see a boy looking through a microscope, and beside him you see a picture of what he sees. This picture does not look like the skin on your hand, neither does it look like the skin on the boy's hand; but it is nothing more nor less than a piece of skin taken from that boy's hand, and it looks just as a piece of skin from your own hand would look if you were to see it through a very strong microscope.
Why cells must not be killed
The whole body is made up of just such little cells as you see in Figure 4, and each cell is alive and has a certain work to perform. It is very important that we keep these cells from dying and that they perform the work for which they are intended, for if these cells die or fail to act, the body becomes sick or dies.
Fig. 4. A cell. (a) Cell body; (b) nucleus; (c) nucleolus.
You can scratch some of the paint from your automobile and the machine will work just as well as ever. Apparently no harm has been done, but an opening has been made through which moisture and germs can enter and cause the wood to rot and the iron to rust. You can remove certain parts of the automobile and still the machine will do its work; but you cannot take away too much of any one part without weakening the automobile, and if certain parts are missing (such as the sparker, the battery, or the steering-gear), the usefulness of the machine is destroyed. So it is with the body. You can scratch off some of the skin and not do any apparent harm, but you have made an opening through which germs may get into the body. You can remove certain parts of the body, such as the arm or leg, and still the body will do efficient service. But there are certain parts of the body that are necessary to life, just as certain parts of the automobile are necessary to the usefulness of the machine. You cannot remove the heart and live; you cannot remove the brain and live.
How cells are killed
You are probably thinking that it must be easy to kill such a little thing as a cell; and so it is. Cells can be killed by too much heat or too much cold. When you skin your hand, you kill many cells, and at the same time make an opening for germs to get in and cause sickness. You can kill cells also by starving them, for they must have not only enough food, but the right kind of food. If you feed your bodies on nothing but candy, pie, and cake, most of the cells will refuse to perform their work and many of them will die. These cells must have also an abundance of air, and the air must be pure and fresh. If you breathe the air that others have breathed or that contains poison of any kind, you will soon find that you are not feeling well. This simply means that so many of the cells are being starved for fresh air, that not enough strong ones are left to do the necessary work. You can kill these cells by overwork, for they must have a proper amount of rest. If you go to school all day long and then sit up until midnight every night, you must not expect the cells of your body to keep strong and well. You can kill these cells by the use of certain things that act as poisons to them, such as tobacco, beer, wine, or whisky.
Questions. 1. In what way is the body like an automobile? 2. What are cells like? 3. Why must cells not be killed? 4. Name five ways by which we kill cells.
Remember. 1. Each part of the body is important to the welfare of the whole body. 2. Each part of the body is made up of very small particles that we call cells; each cell in the body is alive and has a certain work to perform. 3. Cells are very easily weakened and killed. 4. There are five principal ways by which we kill the cells in our bodies: by too much heat or cold; by not giving them the proper kinds of foods; by not giving them enough fresh air; by giving them too much work to do; and by poisoning them.
CHAPTER III HOW CLOTHING AFFECTS HEALTH
Fig. 5. Warm, dry clothing necessary for health.
Why the body should be equally covered
The body should always be kept at as nearly uniform a temperature as possible. In order to do this we wear clothing. Clothing keeps out the heat on a hot day, just as it keeps the heat in and the cold out on a cold day. The clothing should be equally heavy on all parts of the body. It is not right to wear a thick dress over your chest and leave your shoulders and arms bare, or nearly so. People who do this are killing a great many cells by letting part of their bodies become chilled while the rest is warm, probably too warm.
Why clothing should not be too heavy
The clothing should be just heavy enough to keep the body warm. If you wear such heavy clothing indoors that you are constantly perspiring, your underclothes become damp, and when you go out, even though you put on your overcoat, your body becomes chilled. If you begin to sneeze, that is Nature's way of telling you that you are killing many of your cells by too much cold.
People sometimes get warm from exercising, and then take off their coats. They should have removed their coats before they began to exercise. If you take off your coat after you are too warm, your body becomes chilled. Baseball pitchers know this, and if you watch a good pitcher, you will see that he always puts on his sweater as soon as he stops pitching, even though he is very warm. He knows that if he cools off too quickly, he will become stiff and sore and cannot pitch good ball.
When a draft is dangerous
Sometimes a person sits in a warm room until he begins to perspire freely. Then he opens a window and sits in the draft. Under ordinary conditions, the cool wind alone would chill the body, but now the rapid drying of the perspiration makes the body cool still more quickly. The sudden chill causes the person to take cold, which is simply another way of saying that he has killed many cells and caused others to fall sick, so that they cannot perform their work. We cannot get too much fresh air. Drafts do not hurt us if we are thoroughly wrapped up; but it is very dangerous to allow the wind to strike the body when it is not well protected, and especially when it is damp with perspiration.
Fig. 6. Properly prepared for wet weather.
Why damp clothing is dangerous
Damp clothing chills the body very rapidly and kills many cells. Indeed, if a single one of the germs that cause pneumonia were to enter your lungs while you were wearing damp clothing, it would grow so rapidly that you might have pneumonia in a very little while. That is why it is important to change your shoes and stockings as soon as you get them wet, and to take off immediately any clothing that becomes damp. It is hard for boys and girls to keep their feet dry in the winter and spring months, and rubbers are a nuisance; but if you expect to grow into the strong man or woman you picture yourself becoming, you must take care to wear your rubbers. Otherwise you may become weak and sickly, and never be able to do the things you hope to do.
The feet are not the only part of the body that needs to be kept dry. A wet coat is just as harmful as wet shoes and stockings; hence, you should always carry an umbrella or wear a raincoat when you go out into the rain. Umbrellas are unhandy for boys and girls to carry, but if you will remember that thousands of little cells in your body are being injured when you get wet and chilled, you will be willing to take your umbrella.
When to wear an overcoat
In cold weather the same amount of clothing should not be worn in the house and outdoors; for this reason, we have overcoats. If you wear your overcoat in the house, you will become overwarm and your underclothing will then become damp with perspiration; when you go outdoors into the cold air, this dampness will have just the same effect as would dampness that comes from outside.