Graded lessons in hygiene

Front matter

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Preface

The keynote of this book is health. There has been no attempt to prepare an extended treatise on anatomy and physiology. It has been the purpose of the author to present in simple language to the children in the intermediate grades a knowledge of the conditions which tend to preserve and strengthen the body.

While the facts of anatomy and physiology in this book have been made in a sense secondary to the main theme — hygiene — yet they embrace the results of the latest investigations in these departments of research, and are ample for a clear understanding of the central subject. The lessons are designed throughout to come within the comprehension of young pupils, as well as to meet the wants of those in the more advanced classes, in emphasizing the common laws of health. This steady progression from the simple to the more difficult is made by easy, natural, well-gradated steps.

The author regards it not only the most logical arrangement, but also in harmony with the best pedagogy, to embrace the main discussion of the effects of alcohol and tobacco in separate chapters. Connected discussion is better than scattered fragments.

541779

6 PREFACE.

In the teacher's edition of this book, more specific directions are to be found for presenting the subject-matter of these lessons. This supplement for teachers also includes suggested exercises for use in gymnastic drill, as well as a series of tests for hearing, vision, memory, and the methods of making physical measurements. There is albo contained in the teachers' edition a more extended discussion of the effects of narcotics and alcohol upon the human system, and the methods of teaching the same.*

William 0. Krohn.

Chicago, May 1, 1900.

Table Of Contents

OHAPTKB PAOS

I. OuB Food . . . . • 9

III. OuB Dbink - - • - -46

Chapter I. Our Food

Why We Eat. — Does it ever seem strange to you that these bodies of ours do not appear to wear out, though we are constantly using them ? We know that our clothes wear out, no matter how careful of them we may be. A wagon or piece of machinery tends to wear out with each movement it makes. You would not expect your pencil, pocket-knife, bicycle, or skates to keep fresh and new after long and frequent use. Our bodies are constantly wearing out. Every movement of our bodies, however slight, causes at least a small amount of wear. Why, then, do not our bodies waste away ? Because they are being continually repaired. Every little particle of worn-out matter is being replaced by a new one. The food we eat is being changed into the parts of the body that are wearing out.

You are growing very fast. But a few years ago you were much smaller than you now are. Next year you expect to be even larger and stronger. What is it that makes you grow ? Is it the air that you breathe ? No, not that alone. Air is necessary to life ; but you would soon starve if you had nothing but air upon which to live. Water is necessary to life, and yet none of us could live on water alone. You hai^e noticed the little tree in the orchard and the plant in the garden, how

10 GRADED LESSONS m HYGIENE.

"»'# • •♦•,•• • f HI)idly ^^'grc^. If you should stand the plant or tree in

.tte-joiddfe of yput'.schoolroom, on the clean, hard floor, and

•'gfvfe- If sunKglri^'-aif, and water, without any soil, would it

grow ? No ; it would not even live. The roots, by means of

which our little tree, when out of doors, was fastened to the

soil, could not make their way into the hard floor.

If the tree is to live and grow, its roots must go down into the soil and find something for the tree just as necessary to its life, health, and growth, as the air, sunshine, and water. The roots, even the smallest of them, work down into the earth and find food for the tree, and it is this food which the roots find that makes plants and trees grow. The richer the soU — that is, the better the food — the faster they grow. In one garden we find the plants looking pale and sickly, growing scarcely at all, whUe in another garden the plants look fresh and thrifty and are growing rapidly. What causes the difference? You are quick to answer that in one garden the soil is richer, containing more food for the plants, and the gardener loosens the soil that the roots may have a chance to push their way farther and farther into the earth to get more food. The wise gardener also pulls up the weeds that would otherwise grow around the plants, so that these weeds may not use up the food in the soil that the plants need for their health and growth.

Why do you eat ? Because the food keeps your bodies in repair so that they will not wear out, and also because it makes you grow.

Have you ever thought how much one eats in a lifetime? It is a nice problem in arithmetic to figure this out. Nearly every boy and girl in your school eats at least two pounds of food in a day. In a year, then, each of you will eat two tim^s 365 or 730 pounds of food. This is many times your own weight. By the time you have become sixty years old, how much will you have eaten ?

What to Eat. — Our bodies are repaired and made to grow by what we eat. If you eat inferior food your bodies will be made of poor material, and will not grow as fast as they should, or do their work well. If you eat poor, unhealthful food, your body will have to be repaired often ; that is, you will have to call the doctor to give you some medicine to undo the harm caused by the improper food, whatever it may have been. You see how important it is that we know something about our foods. All of us should know what foods are good for us, and what will do us harm. What foods will promote health and growth, and what wiU cause disease and retard growth, is certainly very important knowledge.

Do you think the dark soil in the garden or flower-bed looks anything like the bright-eyed, laughing pansy ? Does the black loam resemble the rich green of the waving branches of the fern ? As we eat the ripe apple, juicy plum, luscious grape, or sweet pear, do we taste anything like the dark, gritty, sandy soil which made it possible for them to exist ? To all of these questions you answer. No. And yet in the same way the roots of the pansy, the fern, and the fruit tree take their food from the soil, and it is then changed so that leaves are made to grow, flowers to bloom, and fruits to appear.

Is it not equally strange to think that the bread, potatoes, meat, and eggs you eat, as well as the milk and the water you drink — in fact, every bit of good food of which you partake — is taken up by the organs of the body and changed into bone, nerve, and muscle? And yet, if we can only get the food into the blood, as the root gets the food from the earth into the sap of the plant, each part of the body will pick out just what it needs to make it strong. The bones will take up from the blood just those little particles they need for their growth and repair, and likewise, the muscles and nerves will do the same. Your own body does not look like the food you eat any more than the plant looks like the soil upon which it feeds. Our food becomes changed in some way into all the different parts of the body — skin, hair, bone, muscle, brain, "and nerve.

Since food thus becomes changed into the different parts and organs of which the body is composed, is it not very important that we be careful to select the foods that are best suited to the repair and growth of our bodies? But before we consider this further, let us follow the food we eat as it makes its journey through the body. The preparation of the food so that it may be used in nourishing the body is digestion. The object of digestion is to separate the food from its hard and useless parts, and then to soften and dissolve it so that it becomes liquid, and can flow with the blood to the various parts of the body requiring food.

How We Digest. — ^The first step in digestion is the proper cooking of the food we eat Our digestion, then, really begins outside of the body. Cooking softens the food so that it can be chewed easily. You would find it difficult to chew raw rice grains. Cooking softens the hard grains of rice, wheat, or oats, anjd it also makes most of the foods taste better. A raw potato does not taste very good, but what boy or girl does not enjoy

OUR FOOD.

eating nicely cooked potatoes at least once a day? Again, cooking destroys many poisons in food. We will learn more about that in the chapter on "Disease Grerms."

Mouth Digestion. — ^After the food is properly cooked, the next step in digestion is to take it into the mouth, where the digestion is continued by chewing and grinding the food with the teeth, and pushing it about the mouth with the tongue. We move it from one side of the mouth to the other untU it is in little, fine particles. While we are. chewing our food well, it is mixed with a watery fluid, called saliva. There are three glands on each side of the mouth that are busy making and secreting this saliva.

You will see their location in the picture. The saliva which the glands produce is sent into the mouth by means of little tubes called ducts. When we eat, taste, or even look at some foods we like, these glands make so much saliva that we sometimes say the mouth waters. You should remember to eat slowly, in order to give

Ftgubb 1.— The Saliyary Glands.

GRADED LESSONS JN HYGIENE.

your teeth a chance to grmd up the food, and also give it time to become well mixed with the saliva of the mouth, which helps so much in preparing the food for the further steps of digestion. After being thoroughly chewed, the food is swallowed.

Stomach Digestion. — In the back part of the mouth, at the throat, begins a long, narrow tube, which passes down to the

stomach. This tube, or food-pipe, is about nine inches long. It is called the esophagus. You all know where the pit of your stomach lies. This is the stomach's center.

The stomach is simply an enlargement of the digestive tube. It is like a large bag with a coat of loosely woven muscles, and it has a queer little gate-keeper or valve (pylorus) at the lower end that will not open and permit the food to pass out imtil it is sufficiently digested and ready for the bowels or intestines. As soon as the food gets into the stomach, the muscular coat begins to contract, first lengthwise and then crosswise. It thus keeps the food churning to and fro, and mixes it with a fluid or juice more powerful than the saliva of the mouth. This fluid in the stomach, so necessary to digestion, is called the gastric juice. It is formed

Figure 2.— The Stomach.

in the many pocket-like glands in the lining of the inner wall of the stomach. The stomach churns away from two to four hours after every meal, according to the kind of food eaten, the way in which it has been cooked, and the health of the person eating it. After each meal the stomach should be allowed to rest a while before the next. This is why girls and boys should, as a rule, eat nothing between meals. If you do, the stomach becomes too tired to do its work well when meal time comes again, and so you are not hungry. Irregular habits of eating, as well as improper, imwholesome food, will cause disorders of the stomach, such as dyspepsia. Again, the gastric juice will not digest the foods in the proper length of time if the pieces are too large and not properly chewed or masticated when swallowed. This is another reason for eating slowly. It should also be remembered that the juices so necessary to digestion are secreted more rapidly and do their work better if we are in a cheerful mood. If we come to the table cross and peevish, the food we eat will not do us as much good and will not be so well digested as it would be if we were cheerful and happy. Cheer is necessary to good digestion.

The blood vessels of the stomach dissolve and take up some of the food and carry it away, but most of the pulpy mass, after being thoroughly mixed with the gastric juice, passes through the little gateway, or pylorus, to the intestines, to be mixed with still another juice.

Digestion in the Intestines. — At the lower end of the stomach the food canal becomes narrow again. This portion of the digestive canal below the stomach is called the intestines or bowels. The intestinal tube is about twenty-five feet long in

GRADED LESSONS IN HYGIENE.

the grown person. This long portion of the food canal is coUed up and closely packed away in the cavity of the abdomen, below the stomach, so as to take the smallest possible amount of room. The last few feet of the intestinal tube is larger than the rest, and is called the colon. The portion directly attached to the stomach is longer, but at the same time much smaller, and is called the small intestine. It is about twenty feet long

and one inch in diameter. The small intestine opens into the large intestine or colon, which is about two inches in diameter, and in the adult about five feet in length. The entire intestinal canal, then, consists of a tube of muscular tissue lined with a mucous membrane. The walls of the intestines are from onesixteenth to one-eighth of an inch in thickness. On their inner surface, imbedded in the mucous membrane, are innumerable small tube-like glands that are very important. They pour out a liquid called the intestinal juice, which does its part in the digestion of food. Along the lower side of the stomach there is a large gland called the pancreas or sweetbread. Each day this pours into the intestines about one quart of a liquid called the pancreatic juice. This juice is even more important than the saliva, gastric juice, or intestinal juice, for it does most of the work of digesting our food. It is so powerful that it breaks up the fats in our food, such as butter

Figure 3.— Showing the Three Coats of the Stomach, (g) Inner surface,

. mucous membrane, (mi) Circular layer of muscular fibers, (me) Outer layer of longitudinal muscular fibers, (p) Ridge of pyloric ring.

OUR FOOD.

and the fatty portions of meats, into very small particles so that they will mix with water. The pancreatic juice also changes the starch in our foods, as the starch of potatoes, bread, and uncooked fruits, into the sugar the body so much needs.

The liver, which is located above the stomach, close Under the ribs and on the right side of the body, is a large chocolatecolored organ, and has for its chief business the making of a fluid called &&. This fluid is also very necessary for the digestion of the food in the intestines.

Fresh human bile is a liquid of a brownish gold color. It is carried to the intestines through a little tube or duct, called the gall-duct. This enters the intestines just a few inches below the stomach. If the liver makes bile faster than it is needed by the intestines, it is stored up in a Httle pear-shaped sac, known as the gall-bladder. This hangs from the under side of the liver. The saying, " bitter as gall," arises from the extremely bitter taste of the bile in the gall-bladder. Sometimes in cleaning a chicken or other fowl in preparation for cooking, by drawing out the liver, intestines, 2

Figure 4.— The Liver— Its Under Surface.

heart, and other organs, the gall-bladder becomes broken, and the bile it contains comes in contact with the meaty portions of the fowl to be eaten. These are rendered, because of the intense bitterness, entirely unfit for food.

While the bile is very important, it of itself does very little of the work of digestion, but its presence makes the pancreatic juice more powerful. Mixed with bile, the pancreatic juice is able to do double the work of digestion that it could do alone. Bile is reaUy a waste substance thrown off by the liver, but on its way out of the body it helps greatly in building up the body. The bile and pancreatic juice enter the small intestine at nearly the same place. The liver is really a wonderful organ. Besides making bile, it aids in various other ways in the digestion of food. It also helps to keep the blood pure by removing from it harmful substances that are formed within the body. The liver also acts as a wide-awake sentinel, in that it destroys many of the disease germs, or microbes, that find their way into the mouth and stomach along with our food. If in healthy condition, the liver will kill germs that might otherwise cause such diseases as typhoid fever, malaria, or la grippe. If any of these little germs, or any other poisons, such as the poisons of poorly canned meats or vegetables, are swallowed along with the food, they are also taken up with the food, and carried by means of the blood tubes into the liver. The liver works hard to keep these poisons from going any farther along the blood tubes to other portions of the body, and thus guards the rest of the body from the effects of the bad food. If the liver gets out of order it sends but httle bile, instead of the quart a day it should send into the intestines.

OUR FOOD.

Poisons are then permitted to pass by unattacked, and the pancreatic juice cannot do the full work of digestion allotted to it. As a result of a disordered liver we have a rather common form of sickness known as biliousness.

Movements of the Intestines. — As the mouth by its movements in chewing the food fine, and the stomach by means of its movements in churning the food about, by rocking it to and fro, from side to side and end to end, so in a similar way the small intestine makes certain movements that mix the food with the bile, intestinal, and pancreatic juices, and forces it farther along the digestive tube or food canaL As the food goes farther and farther along the small intestine, it becomes more and more liquid, untU, at the end, only indigestible portions remain, such as unripe fruit, seeds, peelings, large pieces of food that were not chewed fine enough, and husks of grains, like the covering of the separate grains of sweet com, peas, beans, and the coarser forms of cracked wheat or oatmeal. These waste portions remain solid because the juices cannot act on them and digest them. At this stage of digestion in the small intestine, the food looks somewhat hke mUk with the undigested particles mentioned above floating in it. This food is still in reality

FiouBE 5.— Crofis section of Small Intestine, showing the three layers.

GRADED LESSONS IN HYGIENE.

outside of the body almost as much as if it were still untouched on your plate on the dinner-table. It must pass through the walls of the intestine and get into the blood, and then be carried

to the various parts of the body, before it really becomes food for the bones, nerves, and muscles.

Absorption of Food. — As the food is passed slowly along the small intestine, its hquid parts soak through into the blood tubes, and by the time it reaches the large bowel, or colon, most of the water and all of the useful particles have been removed e^nd carried away by the blood, and only the waste matter, such as seeds, hard portions of unripe fruits, peelings, husks, and the like, mentioned above, remain behind. This is driven on and out of the body. These waste portions, that naturally find their way into the large bowel, should be expelled at least once a day, in order to insure good health. If this is done regularly at a certain time, for example, at about the same hour each morning, the bowels form the habit of always acting at this time. If this waste matter is not given off, we have sick-headache, a feeling of heaviness, and may become ill, for these waste substances are sure to poison the body if retained.

Figure 6.— Showing the DigestlTe Tube, or Food Canal.

You see, then, that there are at least five important organs of digestion. The mouth, the stomach, the intestines, the pancreas, and the liver. Food is softened and prepared for digestion by these five organs by first being properly cooked. Cooking is the first step in digestion. Will you also please remember that there are five digestive fluids: saHva, gastric juice, pancreatic juice, bile, and intestinal juice?

REVIEW QUESTIONS.

1. Why do we eat?

2. Why should we eat several kinds of food?

3. What is digestion?

4. Why should our food be properly cooked?

5. What important fluid in the mouth aids digestion?

6. Why should we eat slowly?

7. What is the stomach like?

8. How long does it churn the food?

9. What important juice in the stomach is necessary to digestion?

10. Why should we eat regularly, and not between meals?

11. What part of the work of digestion is done by the intestines?

12. What help is given by the liver?

13. What juices combine to digest the food in the intestines?

14. How is the food carried through the body to its different parts, after it is digested?

Chapter II. Healthful And Unhealthful Foods

We have learned that digestion is the process by means of which the food we take into the mouth is changed into liquid form, or a state of solution, suitable for being absorbed into the blood. This change may be rapid or slow, according to the nature of the food-stuffs the digestive juices are called upon to dissolve. We all know that it takes much longer to digest a piece of beefsteak than it does a cup of beef tea. We know that milk is more readily digested than roast pork or boiled cabbage. When a person is not very well, when we wish to save labor for the digestive organs and make digestion as easy as possible, the person is placed upon a "liquid diet." How does this help to save work for the digestive organs and digestive juices, when they are not in good, healthy condition?

You have observed that some animals seem to be eating all the time. The hen appears to be continually picking up seeds of weeds and grasses, grains of wheat or com, and countless Httle bugs, as she goes about the yard. Other animals eat large quantities of food at one time, and then lie quiet and sleep for days. I saw a very large snake — a boa constrictor — at one of the parks the other day, that eats only once in two or three months ; but when he eats it takes a very large meal to satisfy him — several chickens, a number of rabbits, and a small army of rats and mice. Other animals, such as the dog, do not chew their food at all. They tear it apart so that the pieces can just be gotten into the mouth and swallowed, and that is all. The stomach and intestines of a dog have thicker and tougher walls, and the digestive juices have more power. That is the reason that dogs can even digest bones which they frequently swallow. You have noticed that the cow will chew her food only a little at first. Notice how fast she eats the grass in the pasture and see how quickly she swallows it. Then while she is resting she brings the food back to her mouth again, and chews it finer. Deer also do the same. It is called "chewing their cud." Once my little girl, when about three years old, saw some deer in one of the city parks chewing their cud; she turned to me and said, "What do deer chew gum for, papa?" Cattle have four stomachs, one of which is called the paunch and is very large. In the full-grown ox it will hold two bushels. The fourth stomach is nearly like man's in size' and shape, and is really the true stomach, for it is the one in which most of the stomach digestion takes place. The other three are little more than storehouses and passageways for the food.

Even some of the small insects have a stomach and intestines which secrete digestive juices. In most worms the digestive tube passes straight through the body. Oysters and clams also possess a stomach and coiled-up intestines. The soft, darkcolored substance at the back part of an oyster or clam is the liver.

Kinds of Food. — Some animals can live on just one kind of food. The cattle on the range will live and fatten on fresh or dried grass alone. The horse will do the same; only he should have oats or com in addition to grass or hay, if he has to work hard. A squirrel likes the kernels of nuts and some of the grains, but does not care for grass. A boy or girl eats more kinds of food than any other animal. Man requires a great variety of foods. He eats vegetables for one purpose, meats from some of the animals for another purpose, and could not live in a healthy condition if he did not have some food, such as salt, from the mineral kingdom.

Different Foods in Different Countries. — In traveling over the earth, we find the people of one country eat things as food that people of other lands could not bear to eat at all. There are people who eat bees and grasshoppers ; others eat rats, mice, bats, and lizards. In some of the French restaurants roasted isnails are regarded as a choice article of food, while to most people they are repulsive. A man who used to chop wood for heating the schoolhouse in which I first taught, used to find nests of black ants taking their long winter sleep in their curiously made houses in the chunks of wood. He would eat the ants with his bread at lunch with great relish. Yet this same man would never eat nice, ripe strawberries, for he said they made him ill. He was certainly a queer fellow, and I am sure his tastes differed from yours as well as my own.

Conditions That Modify the Demands for Foods — The habits of life, as well as the character of the climate, make a great deal of difference in the kind and amount of food eaten. The active man who is working hard at some heavy, muscular labor out of doors, especially in winter, requires a larger amount of food, consisting of a great deal of meat, than does a person whose work is not so hard. You have heard people say when they were very hungry, that they could " eat like a wood-chopper." And we will all agree that the hard-working wood-chopper and miner require more food than would the tailor seated in his shop, or the clerk in a dry-goods store. The miner, the woodman, and the stage-driver are exposed to cold, rough weather, while the clerk, the tailor, and the newspaper editor are sheltered within doors during their work, which, in addition, does not require as much physical energy as does the heavy work the others do out of doors. An Eskimo in the cold, frozen North can eat fifteen pounds of meat a day, to which he often adds larger quantities of fat or blubber. I have been told by Lieutenant Schwatka, the Arctic explorer, that he has seen an Eskimo eat as much as thirty-two pounds of meat and several tallow candles in a single day.