The second book of anatomy, physiology and hygiene of the human body

Front matter

T HE PRICE fixed hereon is fixed by state contract, and any devia¬ tion therefrom shall be reported to your County Superintendent of Public Instruction, or the State Superintendent at Nashville.

Class 0^ 3 L Book C •'

if 0 Q

Preface

This is the second book of a three-volume series of physiologies. The first book is only for children. The third book is adapted to the needs of the highest grades of the public schools, including high schools. This second book is graded to the needs and capacity of intermediate grades.

Serious efforts have been made to present the various subjects in this book in a way that would make them plain and easy, and at the same time to teach some real physiology. A pupil may be interested and entertained with¬ out being instructed; but when interest is once aroused in the important facts of a sub¬ ject, instruction is sure to follow.

The technical terms are used wherever needed. The names are not the difficult parts of a physiology. Technical styles of expression have been avoided, as they are not necessary

IV

PREFACE in a book of this character, and would only make an easy subject appear hard.

A number of experiments have been incor¬ porated in the body of the text at points where they are most beneficial as an illustration. The live teacher will not omit a single one of these experiments, and will encourage the pupils to repeat the same and add others as far as possible. The experiments are an im¬ portant part of this grade of work.

In regard to alcohol and narcotics, we have tried to present the truth as we see it, and as we have learned it from the research and ex¬ perience of others. A broad view should be taken of this subject. In the light of the ex¬ perience of the past, the nature of the sub¬ stance in relation to the cells of the body, and the investigations of modern times, there appears to be nothing to recommend the use of alcoholic drinks as a beverage The matter is thus presented in this series of physiologies.

More cuts than are usually found in an in¬ termediate physiology are given in this book. Good cuts that illustrate the text are very

PREFACE valuable in this stage of the pupil’s progress. A good text-book is always a little beyond the pupil, but the steps must be easy ones from what he knows to what he is striving to get. The cuts must be an aid in making these steps, or they may as well be left out. We have tried to have all the cuts in this book worthy of the space they take.

We wish to acknowledge our obligation to the J. B. Lippincott Company for many cuts which appear in this book.

Through the kindness of Ginn & Co. we were permitted to select two cuts from Blaisdell’s Physiology.’’

Contents

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CHAPTER PAGE

I. Introductory.5

Chapter I

Matter. —All substances and bodies that we know anything about are composed of matter. Anything that we can see or feel is matter. Water, rock, air, wood, bone, iron, gold, and so on, are all forms of matter. Our bodies are made of various kinds of material substances which we take into the body by eating, drinking, and breathing.

Lifeless matter. —Lifeless matter is the kind that never moves or does anything of its own accord. Stones or wagons are lifeless because they will never move unless some outside force pushes or pulls them. The greater part of all the matter in the world is of this kind. The whole crust of the earth and all the water and the air are lifeless mat¬ ter. The wind blows only when the sun makes it do so, and it, in turn, may raise waves on the water.

A living body. —A living body is com¬ posed of matter, but the matter has been made over by a force called life .

We can tell whether or not a body is alive, in three ways : (i) Within all live bodies there is motion. The heart beats, the breast rises and falls in breathing, and sap circulates in trees. (2) A live body can take up lifeless matter and make it part of its own body. All live bodies must have some kind of food. In that way they grow and get strong. A stone does not grow or do any work. (3) All live bodies can start the growth of other bodies just like themselves. An apple-tree produces seeds which will sprout and grow up into other apple-trees of the same kind.

In short, then, all live bodies have motion within themselves , take in food , and produce other bodies of their own kind.

Animals and vegetables. —All live bodies are either animals or vegetables. In some re¬ spects all live bodies are alike, but there are a number of plain differences between animals and vegetables.

A vegetable is fixed to one place on the ground, while an animal can move about. A vegetable lives on a very simple kind of food which it gets from the ground through its roots, or from the air through its leaves, while an animal can live only on vegetables or other animals. Animals can feel and choose, while plants have no such power.

Animals are a higher kind of living bodies than vegetables.

Man’s place among living bodies.—

Man is the highest of all animals. His body is not so large or so strong as that of some of the lower animals, but he has the best brain, and hence can know more than any other animal. A man can think, reason, invent, make plans, and prepare for the future. These things make man the master of all other animals.

Since this is so, we should think that all men would try to know all they can learn about their bodies and minds, and would be careful to observe the laws of good health.

Many people do not take as good care of

their health as some of the lower animals do.

Either they do not know any better or they are not willing to do what they should do. It makes no difference what the cause is, any one who does not obey the laws of health will have to suffer in some way.

Purpose of this book. —The aim in this study is to learn all we can about the human body. When we know how nicely the differ¬ ent parts of the body are made and joined together, and how well all the parts work for the good of the whole body, we will certainly try in every way to help them, or at least will do nothing to hinder them.

We will study this book, then, to find out the laws by which our bodies work, and then learn how to obey these laws so that we may have good health.

Why we should study physiology.—

The human body, in one sense, is a machine. No one should try to run a machine unless he knows something about it.

If you were placed in charge of a printingpress, and were anxious to have it do the best kind of work for you for a long time, what would you do? No doubt you would care¬ fully examine it to see how it was put together and what work each part had to do. You would run it in such a way that it would do the best kind of printing for you. You would keep it clean, well oiled, and not allow any¬ thing to get into the cogs and break them. If any accident should happen to the press,, you would then know what to do.

We study physiology for similar reasons, (i) To find out what the different parts of the body are. (2) To find out the use of each part. (3) To find out how to take proper care of the body.

The body composed of cells. —The

body is made up of many millions of very small bodies called cells. The cells are so small that they can be seen only with a good microscope. The flesh, the bone, the skin, the hair, and so on, are all made up of a great number of these little cells. In Fig. i the

Fig. i.—A cell, a , cell-wall; b , albumin ; c, nucleus.

parts of a cell are shown. Within the cell, at some point, is always a nucleus. Around the nucleus is the albumin. Outside of all is the cell-wall. The nucleus is the centre of the life of the cell, and without it the cell would soon die. The albumin is a substance about like the white of an egg. It makes up the larger part of the cell. The cell-wall forms a little chamber, or cell, in which the nucleus and albumin are placed. In most vegetables this wall is thick and strong, but in animals it is -often very thin or entirely wanting.

Forms of cells. —When a great number of cells are joined together to form a body

Fig. 2.—Cells of various kinds. /, plant cells ; s , pavement cells; t, columnar cells ; w , ciliated cells; m y muscle-cells ; tt y nerve-cells.

like that of a tree, a horse, or a man, the cells press against each other and are made to have many different shapes. Also, the different kinds of cells have different kinds of work to do, and they are made so they can do their work in the best way. In Fig. 2 you can see the shapes of several kinds. The upper one shows some cells arranged in the tip of a root of a plant, s shows a few flat cells joined edge to edge like stones in a pavement, i shows a few cells standing on end like columns. The cells shown in w have cilia, or hair-like pro¬ jections on top. Two different kinds of muscle-cells are seen at m , and two nerve-cells at n. There are a number of other cells of different shape, each being adapted to the kind of work it has to do.

Single - celled animals. — There are a great number of very small animals which are composed of but a single cell. They are, in most cases, so small that they can be seen only with very strong microscopes.

A very good example of this kind of animal is shown in Fig. 3. It is called the amoeba . It lives in water and moist earth. If you could see one of them it would look like a very small lump of jelly with a round dot in¬ side. If you would continue to watch it, you would see that it is alive, for it would begin to

Fig. 3.—The amoeba.

move in a very peculiar way. It has no feet, but instead it pushes out one side of its body in the direction it wishes to go and then rolls the rest of the body into it. In that way it moves along, and when it rests it is in the shape of a tiny ball.

It has no stomach or mouth, but when it meets any small particles of food it wraps its whole body around it and takes the food into its body. In that way it can make a stomach for itself whenever it needs one.

The amoeba lives much as other animals do ; but its life is very simple, for it has only one cell, and must use it for everything it does.

The human body made of cells.— A

great number of cells much like the amoeba are found in the human body. They float about in the blood and move through other parts of the body. They are called white corpuscles, and will be described in a later chapter.

The most of the cells of our bodies do not move about. The muscles, bones, skin, brain, liver, and so on, are all made up of many cells ; but they are fixed to one spot and their food is brought to them by the blood.

One cell cannot do very much, but when a great number of them work together to do the same thing they can do a great deal. One boy cannot pull a heavy wagon along the road, but when a number of boys all pull and push in the same direction, the wagon can be moved along rapidly.

A division of work among the cells of the body. —In a large factory of any kind the work is divided among the men who are at work there. If they are making shoes, one set of men will prepare the leather; another will

*5 cut it out; another will sew the pieces to¬ gether, and so on till the shoe is complete. They can make shoes much better that way than if each man tried to do all the different kinds of work.

The human body is like this factory, and the different sets of men at work are like the dif¬ ferent groups of cells in the human body.

Each group of cells has become used to one kind of work and does not try to do any other kind. The cells in the stomach look after the digestion of food. Those of the skin work for the protection of the outside of the body. Those in the muscles move the body. Those in the heart keep the blood in motion. Those in the brain reach out long arms to the other cells and control their action. A great num¬ ber of groups of this kind are engaged in doing a special kind of work, and each can do better work than if it tried to do many dif¬ ferent things as the amoeba has to do.

An organ. —An organ of the body is com¬ posed of a large number of cells which work together to do a certain thing. The stomach is an organ of digestion. The lungs are the organ of breathing. The eye is the organ of sight. The ear is the organ of hearing. Whenever we use the word organ in this book, it will mean a collection of cells which are all working together to do some important work for the body.

The different kinds of matter in the body. —The whole body is made up of water , albumin , fat , minerals , and a little sugar. About three-fourths of the whole body is water. Even the cells of the hard bone and teeth are partly water.

The albumin is a very important part of all the cells. In a good-sized man there are about twenty pounds of it.

About ten pounds of a man’s weight is fat, sometimes more and sometimes less than that amount.

Minerals are found in all parts of the body, but mostly in the lime in the bones. Salt is a mineral found in all the cells.

J 7

How the body is kept alive. —The body is a machine, and, like all machines, it must be kept going or it will stop. Food and air are the two things which we take into the body, and they keep the cells alive and make them able to do work.

What does the engineer do when he wants his engine to run ? He shovels good coal into the fire-box under the boiler, and opens the damper so the fire can get a good draft of fresh air. The coal is the food of the engine and the draft of air is its breath. As long as the coal and air are supplied, the engine can be kept running; but as soon as either fails, the fire goes out and the engine stops. The engine may then be said to be dead, but a fire may be started in it at any time, and it is then alive again.

Eating and breathing are the two most im¬ portant things we have to do. The food and the air do for us what the coal and air did for the engine. We have to eat about three times a day, and must breathe constantly both day and night. If we could not get food and air jg SECOND BOOK OF PHYSIOLOGY

the body would soon die, and, unlike the en¬ gine, life could not be started in it again.

QUESTIONS.

1. What is matter ?

2. What is lifeless matter ? Give some examples.

3. In what three ways does a live body differ from lifeless matter ?

4. What are the two kinds of live bodies ?

5. Give three important differences between animals and plants.

6. Give some good reasons for studying physiology.

7. What three things should we find out by this study ?

8. What are the three parts of a cell?

9. Draw on paper or the blackboard several cells of different shape.

10. Describe the amoeba. How does it walk and eat ?

11. What is the human body composed of ?

12. How is work divided among the workmen in a large factory ?

13. How is work divided among the cells of the body ?

14. What advantage is there in having different groups of cells for each special kind of work ?

15. What is meant by an organ of the body ?

16. What five substances are in the human body?

*9

17. How much of the whole body is water?

18. How much of the body is albumin?

19. How does an engineer keep his engine going?

20. How do we keep the body alive and able to do work ?

Chapter II Food

What food does for the body. —Food does three things for the body. (i) It adds to the weight of the body. A growing boy or girl needs a great deal of food for this pur¬ pose. When they are full grown their weight will change very little during health. (2) The food unites with the oxygen of the air which we breathe and produces heat. A healthy body has almost exactly the same temperature all the time. (3) Food stores all the cells with material which they can use in doing work. In walking, running, and working the muscles are active and use up the material which the food brought to them.

In short, then, warmth, growth, and ability to do work are the three things which we get from food.

Why we have to continue to eat.—

Some one might say that he eats because he

FOOD is hungry, but that would not be correct. We get hungry only when we need more food. We have to keep on eating because the food is rapidly used up and the body is constantly wearing away. Every breath which is breathed out from the lungs carries heat and water out of the body. On a cold day, even when we are well clothed, a great deal of heat gets away from the body. The body gets its heat only by burning up some of the food which we eat, and so that is one reason why we get hungry.

The chief purpose of food is to furnish energy, that is, ability to do work.

When a man works hard he soon gets hun¬ gry, and needs to eat more than one who is idle. This is because the food which is stored in blood and in the cells of the body is rapidly used in doing work. Then the man eats again and uses that food in doing more work.

The skin is constantly wearing off and new cells from beneath form new skin.

In other ways, too, the body is constantly losing material, so that, in all these different ways, the body of a man who is doing hard work will lose about nine pounds a day. This must be supplied by the food which the man takes into his body.

What a food is. —A food is anything that will nourish the body without doing it harm. Bread, milk, meat, eggs, and many vege¬ tables are good foods because they supply the cells of the body with what they need. Alcohol is not a food, because, even if it does make the body warmer for a time, it also injures the cells.

Difference between the food of plants and animals. —The chief difference between a plant and an animal is in the kind of food which they use.

All animals live on plants, and plants live on the food which they get from the soil and the air. All plants are at work making food for animals. If plants should cease to grow, all animals would starve for want of food. When we eat beefsteak we eat the food which

FOOD

2 3 the ox got from the plants. The food in an egg was obtained by the hen from the plants. All of our food was prepared first by vege¬ tables.

Different kinds of food. —There are three important kinds of food. They are proteid y starch , and fat.

The proteids are the most important of all. The larger part of a living cell is proteid, and, as it is constantly being used up, the food must bring it a new supply. The white of an egg is almost all proteid. Proteid is found only in the live cells of animals and vegetables.

Starch is also an important food which is prepared for us by the vegetables. Wheat, corn, oats, potatoes, and many other vege¬ tables contain a large quantity of starch. The starch itself is not a food to the cells ; but the body has an easy way of changing it to sugar, as we will explain in the next chapter, and the cells then use the sugar.

The fats are obtained chiefly from fat meats, butter, milk, oils, and nuts. Fat is food which is stored up in the body. It may not be needed just at present, but it is always ready for use. When an animal cannot get food, it will live a long time on its fat, and then it will be very lean.

There are two other substances which we must have, and they may properly be classed as foods, though they are used in a different way from the three great foods named above. These two are minerals and zvater.

The minerals are needed to build up the parts of the body that do not change very much. Bone is hard and strong because it contains a great deal of lime. All the ma¬ terial from which bone is made must come from the food which we eat.

Salt is another important mineral which is needed by all the cells. There is some salt in our food, and we add a great deal more in cooking or at the table while we are eating. Other minerals are also needed, but they are already in the other foods.

Water is not used up in the body as the proteids, starches, and fats are, but it is always

FOOD

2 5 needed to dissolve the other foods and to float them out to the cells. A cell can neither work nor get its food unless it is bathed in water. The impurities which are made in the body must be washed away, and this is always done by the water. A man can live many days without the other foods, but he would hardly get through a single day without water.

Good water. —A man needs about three quarts of water every day. Part of this is taken with other foods, such as milk and vege¬ tables ; but he must drink a great deal besides.

There is little danger that any one will ever drink too much pure water. Most people drink too little. The great danger lies in drinking water that is not pure.

Water may be very clear and yet be very impure. The little germs of disease which live in water are so small that they cannot be seen with the naked eye. Water may be muddy, and yet be purer than some clear water. A filter may make the water clear, but it will not always make it pure. When water has a foul smell it is not fit to drink; but im¬ pure water cannot always be detected by the smell of it. How then can we tell whether the water which we drink is pure or not ? It is not always an easy matter. A bottle of the water may be sent to a chemist once in a while, and he can analyze it and see if it con¬ tains any impurities; but most people cannot go to that trouble and expense. The best way is to avoid water found in places where it is likely to be impure. The water in shallow wells, stagnant pools, and rivers into which the sewage of a city is emptied, is never safe to drink.

Shallow wells. —When it rains, the water either soaks into the soil or runs into the low places, forming the lakes and rivers. The part that soaks into the ground will run through cracks in the rock or through openings of any kind in the ground. In that way numerous veins of water are formed in the earth, some close to the surface and some deep in the rock. There are so many of these veins that

FOOD when we drill or dig into the earth we are almost sure to strike one of them and get a well of water. When a well is drilled deep into the rock and cased up with iron tubes, the

Yig. 4.— The kind of wells that are liable to contain impure water.

water in it is almost always pure and good to drink. This is so because the water has soaked through layers of sand, gravel, and clay, and then passed back and forth in the crevices of the rocks down to the bottom of the deep well. This is nature’s way of filtering water and making it pure.

Impure well-water is nearly always found in shallow wells. This is what we would expect. The rain-water gathers up many impurities, decaying matter, and disease germs and car¬ ries them into shallow wells. Such wells are often twenty, thirty, or forty feet deep, and are walled up with stone. Foul water can run through the wall into the well. The platform upon the well and the sod around it may be kept very neat and clean, but still the water may become very foul. Filth from a barnyard, outhouse, or sewer may be carried into such a well by a vein of water under the ground. Typhoid fever and other diseases are often caused by drinking water from such wells.

Shallow wells are always likely to contain foul water, and should be avoided if possible. Such wells in a city or town are much more dangerous than in the country.

City water. —Many cities and towns are supplied with good water from wells and

FOOD springs or lakes. Such water is often brought from a long distance and pumped through pipes into the city. One of the most im¬ portant things a city or town has to do is to supply its people with good drinking-water. City water sometimes also becomes impure and many people become sick, for everybody must drink water. When it is suspected that water contains germs which cause disease the only safe course is to first boil the water for twenty minutes or more. This will kill all living germs.

Freezing the water will not purify it. It is a bad practice to put broken ice into the drink¬ ing-water. The ice may be impure, and it makes the water too cold for a healthful drink.

Some good foods. —Wheat is one of our best foods because it contains all the different kinds of foods we have named. It is rich in proteid and starch, and also contains some sugar and fat. Dough made of flour is sticky because of the gluten in it, and gluten is chiefly

3° a proteid food. When yeast is mixed with it, the whole lump of dough will “rise.” This is caused by millions of little yeast-plants which grow rapidly in dough. They set free a great number of bubbles of gas called carbon diox¬ ide. The sticky gluten holds the bubbles in the dough, and as the amount of gas increases the dough is forced to “ rise.” When the dough is placed in a hot oven it will rise rap¬ idly, because the heat makes the gas expand. Baked bread will contain numerous holes where the gas was formed.

One can live very well on good bread and butter alone.

Corn is rich in starch and fats, but has only about one-half as much proteid as wheat has. That is why corn bread will not rise as well as wheat bread. Corn bread is a wholesome food.

Peas, beans, potatoes, and many fresh veg¬ etables are also desirable foods when mixed with other foods.

Meats and eggs are rich in proteid and fat. They are valuable foods for men who do hard

FOOD

3 1

work, but not so good for boys and girls or for those who sit at their work all day. Meats should always be well cooked. Beefsteak is much better than pork.

Good milk is a perfect food for children, but it alone is not enough for people who are grown.

The need of a mixed diet. —While bread contains all the different kinds of foods, it is not best to eat bread alone. We would have to eat too much starch to get the right amount of proteid. It is better to eat some good meat or egg with the bread. In that way we can get just the right amount of each kind. Fresh vegetables and fruits are also necessary to a good diet.