Keeping the laws, a first book on physiology

Book III A First Book On Physiology

BY

JOHN W. RITCHIE

PROFESSOR OF BIOLOGY, COLLEGE OF WILLIAM AND MARY IN VIRGINIA

AUTHOR OF NEW-WORLD HEALTH SERIES, AND OF " HUMAN PHYSIOLOGY "

IN NEW-WORLD SCIENCE SERIES

Illustrated by

YONKERS-ON-HUDSON, NEW YORK

WORLD BOOK COMPANY

New- World Health Series contains the widely used Primer of Hygiene, Primer of Sanitation, and Primer of Physiology, for elementary schools, sometimes known as the Three Health Primers. These Primers are revised from year to year and kept thoroughly up to date, but a wholly new set, in large part rewritten, has recently been included in New-World Health Series, as follows :

Book I : Learning to Live, A First Book on Hygiene. By John W. Ritchie, Cloth. Illustrated. In press

Book II : Clearing the Way, A First Book on Sanitation. By John W. Ritchie, Cloth, Illustrated. J ust published

Book III : ICeeping the Laws, A First Book on Physiology. By John W. Ritchie. Cloth. Illustrated. Just ptibltshed

Books II and III : Life and Health, Consisting of Clearing the Way, a First Book on Sanitation, and Keeping the Laws, A First Book on Physiology. By John W. Ritchie, Cloth. Illustrated.

Just Published

WORLD BOOK COMPANY

Established 1905 by Caspar W. Hodgson YONKERS-ON-HUDSON, NEW YORK 2126 PRAIRIE AVENUE, CHICAGO

,7^

JUN29I9I8

Copyright, iqiby iqij^ by World Book Company. Copyright in Great Britain. All rights reserved,

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Preface

In this the most advanced volume of a series of elementary school texts, the author has attempted to give the pupil a general idea of how the body lives ; to arouse in him a desire to put himself into harmony with the laws of his physical being; and to furnish him with information that will be useful in his efforts to lead a hygienic life. To the writer it seems especially important to build, during the time of youth, a right mental attitude toward matters of health. Space has therefore been found for a consideration of the reasons for hygiene and for a discussion of the principles of health and of the results of living in accordance with them.

To the author it seems absolutely fundamental that in a democracy the individual be put into possession of the information on which he is supposed to base his conduct, especially when questions that affect the actions, not of an hour but of a lifetime, are involved. In this text, therefore, advice on matters of hygiene has been accompanied with the facts on which it rests, whenever this has been possible. It is believed that by thus providing a basis of sound hygienic information a receptive spirit on the part of the pupil is insured, and that this greatly increases the effectiveness of all the health work in the schools.

For advice during the preparation of this text the author makes acknowledgment to Dr. Charles P. Emerson, Dean of the Indiana University School of Medicine, who has read the greater part of the manuscript.

Contents

CHAPTER PAGE

1. Life and Health 157

2. The Human Body and the Cells of Which It Is Built 161

Chapter One Life And Health

Fig. I. The length of time a top will spin depends on the conditions under which the spinning is done.

Three boys threw their tops into a ring. One top hit a small stone and fell on its side. The second top struck in a sandy place in the earth and in thirty seconds its spinning was over. The third top found itself on smooth ground and it continued to spin for more than a minute.

How long will a top spin ? We cannot say. It depends on the conditions under which the spinning is done.

The length of human life. There is a common idea that the body has a certain " natural " Hfetime. This idea is not correct. In Europe three hundred years ago the average human life was twenty years. In 1910 it was

Europe forty years. At the present time in India it is twenty-four years. In Indiana it is forty-five years, and in Sweden it is fifty-two years. In New York City twelve Sweden years have been added to the

average life since 1866, and in Massachusetts Indiana from 1900 to 1910

human life lengthened at the rate of six months each year.

During this period, therefore, the people of Indiana may be said to have won back one half India the time that the passage of

Uthe years took from them.

The human machine may be destroyed in its first month by lack of proper food ; it may suddenly be wrecked by disease germs after it has been running smoothly for twenty-five years ; 52 yrs. 45 yrs. 40 yrs. 24 yrs. or it may give good scrvicc for Fig. 2. A diagram showing the sixty. Seventy, eighty, or even

average length of life in different ^^^ hundred ycarS. A top parts of the world. The length of -' ^

time the human body lasts depends SpiuS longer On a SmOOth than

on the care that it receives. q^ a rOUgh SUrfaCC, and the

human body lasts longer when it lives and works under good conditions than when it is neglected and abused.

Preventing sickness. In Ceylon for each looo people there are each day, on an average, 65 persons sick. In Spain for each 1000 inhabitants the daily average of sick persons in 191 2 was 44 ; in the United States it was 28 ; in Denmark it was 26 ; and in New Zealand it was 18. In London, Paris, Berlin, Munich, and Amsterdam in 1880,

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LIFE AND HEALTH

Cevlon

Spain

United States

New Zealand the daily average number of the sick was 55 for each 1000 inhabitants ; by igog the number had fallen to 31.

These facts prove that the amount of sickness in different countries depends on the intelHgence that the people use in caring for their health.

They show that to a great extent a nation can decide for itself how many of its people shall each day be sick and how many of them shall be well.

Disease prevails because of ignorance. If it is possible to escape sickness, why do men suffer from it ? It is because

Fig. 3. A diagram showing the most persons do not under- average daily number of sick per-

stand that health can be de- sons per 1000 inhabitants in dif-

T T T 1 TTT.^i . ferent countries in 1912. The

served and earned. Withm . r • i •

w^x VV.VX C4.11VX ^«.Axx^v^ iLxxxii ^j^q^j^^ ^f gickuess m any country

the last forty years the real depends to a great extent on the

causes of many diseases have ^"^^" ^^ inteUigence its people

^ use in dealing with matters of

been discovered, and the way health. to prevent many of the most

important of them is now known. This knowledge has come into the world very suddenly, and people in general do not yet understand it. All over the world, therefore, because of their ignorance people are still suffering from disease. The ancient Greeks taught that knowledge is virtue and that ignorance is sin.

^ We suffer from disease because of ignorance; we escape it through knowledge. — Richards.

l6o KEEPING THE LAWS

The great sin in the world of health today is ignorance, and we are punished for this ignorance by the preventable sickness that is among us.

Keeping the laws of health. Cut your finger and you will suffer; burn your hand and you will smart for it. Keep the laws under which your body lives and you will enjoy health ; break them and you must bear the punishment. You did not make the laws of health ; you can- Ai ^. ^ not chans^e them. Nature has laid

Fig. 4. Alexander the ^

Great. He died at the age down her rulcs, and the wisc coursc

of 33 because he paid no f qj. yQ^ ^O f ollow is tO find OUt what attention to his health. , , , 1 . i x 1

they are and then obey them. In the second part of this book we shall study the human body and the laws of its life.

What was the average length of life in Europe 300 years ago ? What is the average length of life at the present time in India ? in Massachusetts ? in Sweden ? In New York City how^ much has been added to the average life since 1866 ? How rapidly did human life lengthen in Indiana from 1900 to 1910? Is there a ''natural" lifetime for the body? Give a reason for your answer.

How many persons are sick each day for each 1000 inhabitants in Ceylon ? in Spain ? in the United States ? in Denmark ? in New Zealand? How much has sickness decreased in certain European cities during the last 30 years ?

Why do people allow preventable illness among them ? What result follows the keeping of Nature's laws ? What is the result of breaking these laws ? What course should we pursue with regard to them ?

Chapter Two The Human Body And The Cells Of Which It Is Built

Have you ever watched a little plant push its way out of a seed, thrust its roots downward into the earth, and unfold its leaves to the light ? And have you seen such a plant grow larger day by day, until finally it blossomed and bore seeds like the one from which it grew ? If you have worked in a garden and understand plants, you must often have thought that they are very much like the people about us in the way they grow and go through the cycle of their lives. This is indeed the truth, and, in order that you may better understand your own bodies, we shall begin this chapter by learning something of the structure of a plant and of how a plant grows.

A plant composed of cells. If you could examine a small portion of a leaf or other living part of a plant under a microscope, you would find that, like the human body, it is made up of cells. Each cell is composed of a half-liquid living material, which is inclosed by a cell wall. In the center of the living matter is a denser portion, which is called the nucleus. Each cell is alive ; each takes in food and does all those things that make a living plant or animal different from sticks and stones and other things that are not alive.

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Fig. 5. The life cycle of the bean.

1 62

Fig. 6. A pine seed cut open to show the young plant in it.

How the young plant starts from a cell called the egg.

Break open a seed and you will find in it a young plant.

Where did it come from ? It grew from a cell called the egg. This cell at first is like the other cells of which the seed is built, but at a certain time it increases in size and gathers to itself a rich food supply. It then begins to divide, and from it the new plant comes. Before we begin the story of its growth, however, there are some other facts that it is well for us to understand. The parts of a flower. Examine almost any common

flower, and you will have no trouble in recognizing the

parts shown in Figure 7. First come the little green

sepals, then the bright-colored petals, next the stamens^

and in the center one

or more pistils. The

lower part of the pistil

contains the young

seeds and becomes the

seed pod. In the heads

of the stamens is a

fine, powdery substance

called/^//^;^. When we

examine pollen under

a microscope, we see

that it is composed of

a great number of little grains. Each little grain is, in

reality, a cell; each contains living matter and a nucleus,

as do other cells.

The egg fertilized by the pollen. Bees visit flowers for

the nectar that is in the blossoms and for the pollen,

Fig. 7. The parts of a flower. To the left is a pistil cut open to show the location of the young seeds.

THE HUMAN' liODV AND ITS CELLS

1^)3 is shown growing out from the grain.

which they gather and mix with honey in making '' bee bread " for their young. In passing into a flower

Fig. 8. Pollen grains, ^^d out of it, a bee often leaves pollen

On the left a pollen tube on the sticky outer end of the pistil. When a pollen grain is thus left on a pistil, a long, threadlike tube grows

out from it, makes its way down through the pistil

to a young seed, enters the seed, and finds the egg

(Fig. 9). Then a nucleus from the pollen grain passes

out of the tube and unites with the

nucleus of the egg. The uniting

of the nucleus of the pollen grain

with the nucleus of the egg is

called fertilization^ and the egg is

said to be fertilized, because in

some way it is given the power to

grow and make a new plant.^ The growth of the egg into a new

plant. After the egg is fertilized,

it begins to grow. In a very short

time it divides into two cells.

Each of these again divides, making four cells, and the process

goes on until there is a group of

many cells, which have come from

the dividing of the egg. From these cells are formed

the roots, the stem, the leaves, and the other parts of pollen grain

pollen tube

Fig. 9. Diagram showing how the pollen tube passes down through the pistil to the ^gg.

1 When the pollen is washed away by rains, or when the spring is so cold and wet that bees and other insects cannot visit the flowers, the strawberry, plum, peach, and cherry crops fail. Without the pollen the eggs in the young seeds do not grow, the seeds die, and the fruits drop off.

the new plant. The outer ones change into skin or bark to protect the delicate living cells within. Some change into long wooden vessels to carry water from the earth up to the leaves ; some form vessels for carrying food throughout the plant ; and other cells take up all the different kinds of work that must be done within th^ plant. Usually the little plant stops at a certain stage of growth and rests within the seed until the warmth of

C D

Fig. io. Four stages in the development of the young plant from the ^gg. A represents the Qgg, B shows the division into two cells, and Cand D are later stages. In two of the cells in C, the nuclei have divided, but the new cell walls have not yet been formed.

the next spring stirs the cells into renewed activity and calls the plant forth to a new life.

The growth of the human body from a single cell. The human body, like the body of a plant, starts from one cell. This cell divides and redivides until it forms a great cluster of thousands of cells. Of these cells all the organs and parts of the body are built. Some cells build lime around themselves and form the bones. Some build a great network of tough fibers, called connective tissue fibers, which hold all the body together. Other cells make up the muscles; certain cells form organs for digesting the food ; the outermost ones make for the body a tough covering which we call the skin ; a great

THE HUMAN BODY AND ITS CELLS

I6S group in the head and along

the back become the brain

and nervous system; and

still other cells become fitted

for doing all the other kinds

of work that must be done

in the body. Thus we see

that the human body, like

the bbdies of all living things,

whether they be plants or

animals, starts with a single

cell; and that when the body

is grown, all its parts are

composed of cells, or of supporting substances, like bone

or connective tissue fibers,

that the cells have built.

The plan of the human body. When the growth of the human body is complete, we find that it is built according to a plan that is much like the plan of the bodies of other animals. Like the bodies of all the higher animals and of birds, frogs, and fishes, it has a head and trunk, and to the trunk are joinqd two pairs of limbs. In the back we find the jointed spinal column (page 171), which stiffens the trunk and at the same

On the right is . . i i i

nerve cell from time allows it to bend ; through the the brain; on the left, other parts of the body there are

a muscle cell from the , ....

stomach. Supporting bones with joints that

Figs, ii and 12. In its first stage connective tissue is a group of cells which build around themselves a mass of jelly-like material, as shown in Figure ii. This material hardens into the fibers that are seen between the cells in Figure 12. All through the body a framework of connective tissue runs, holding the cells, organs* and tissues in place.

Fig. 13. shown a heart stomach intestine permit movement at certain places ; and within a large cavity in the front of the trunk are placed a set of great organs, each of which carries on some work that is necessary for our life.

Among these organs are the stomach, intestine, and liver, which are concerned with the feeding of the cells ; the lungs, which take in oxygen and give off carbon dioxid ; the heart, which pumps the blood with its stores of food and oxygen through all the body ; and the kidneys, which remove poisonous wastes from the blood. Other important organs in the human body are the brain, which lies securely within the skull, and the eyes, ears, and nose, through which the brain learns about the outside world. In later chapters we shall study in more detail all these organs and their work.

Learning to care for the human body. In the first part of this book we studied about disease germs and how to avoid them. This is a most important subject ; for when germs get into our bodies they are like weeds in a garden, and we cannot have health while they are growing among our cells. At the same time, we must remember that if there were not a disease germ in all the world, so wonderful a machine as the human body with all its delicate

Fig. 14. 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.

THE HUMAN- JWDV JND ITS CI.LLS organs and parts would still require intelligent care. A gardener not only fights weeds; he also waters his plants and supplies them with the food materials which they need. So to keep our bodies in health we must not only avoid disease germs but must also keep all our organs at work so that our cells may have the right conditions for their life. In order that we may know how to do this, we must understand the human body and its needs.

Anatomy, physiology, hygiene.

Anatomy is the study of the structure of the body, — of the way its organs and parts are made and how they are all united to form one whole. Physiology is the study of the functions of the body, — of how the body lives and of the work that each part does to keep up the life of all the cells of which the body is composed. Hygiene is the study of how to care for the body, — of what we must do to keep ourselves in health. It is necessary for you to study anatomy and physiology in order that you may understand your body and its needs, and you should understand hygiene because it teaches you how to keep your body strong for the work that is waiting for you in the world.

Fig. 15. Cells from the lining of the trachea, fl! is a cell that manufactures sticky mucus {b) in which dust and germs from the air are caught. The cilia {c) on the other cells are very fine, hair-like processes that beat upward and sweep the mucus, dust, and germs up out of the air passages and lungs.

Of what is a plant composed ? Describe a cell. Where does the young plant within a seed come from ? Name the parts of a flower. What is pollen ? Why do bees visit flowers ?

What do they do for flowers ? What grows from the pollen grain when it is placed on the pistil ? What is fertilization ? Describe the growth of the ^gg.

From what does the human body start ? Of what are all the organs of the body built ? Name some of the different kinds of cells and tissues in the body. Name the principal organs of the body and explain the work done by each.

What is anatomy ? What is physiology ? Why do we study anatomy and physiology ? What is hygiene ? Why do we study hygiene ?

Chapter Three

Any one looking at the solid walls of a tall building would naturally suppose that these walls carried the weight of the great structure above them. As a matter of fact, the building has a steel framework which supports it and braces it in time of storm, and the walls do not bear even their own weight. This is shown by the fact that the workmen often finish a portion of the wall many stories above the ground, before they build in the parts that connect it with the earth. The important thing in supporting the building, therefore, is the hidden framework which outlines the shape of the building and carries its weight; it is not the walls, which are a mere covering hanging on the framework.

The skeleton. The human body, like a great building, has a framework which gives the body its shape and provides support for it. This framework is composed of 206 bones. All the bones taken together are called the skeleton.

In addition to supporting the body, the bones protect delicate organs like the brain and heart, and make it possible for the muscles to move the different body parts. Feel your wrists, your sides, your cheeks, or almost any part of your body, and you will find the bones under the skin and soft flesh. We shall now

Fig. 16. The weight of the building is carried by the steel framework.

I/O cranium clavicle sternum

humerus tarsal hones

metatarsals ^phalanges

Fig. 17. The skeleton.

study the more important bones of the skeleton and the way in which these bones are joined to make a framework for the body as a whole.

The spinal column the center of the skeleton. The backbone, or spi7ial cohcmii, is the center around which the whole skeleton is built. Not only does it run up the back and stiffen and support the trunk, but it also carries the head on its top, and it has the bones of the chest and the bones of the hips attached to it. It is composed of many short bones, — an arrangement which gives it a great number of joints and enables it to bend freely and easily in any direction. Each bone of the spinal column is called a vertebra (plural, vertebrce). Five of the lower vertebrae are joined to make one large, solid bone which is called the sacrum. Below the sacrum there are three or four small vertebrae which form a little tail-like structure, the coccyx^ on the end of the spinal column.

The skull. The skeleton of the head, or skull, is composed of the

fourteen bones of the face and of eight bones which make a strong box (the cranium) to protect the brain. In the skull of a little baby there are places where the bones

Fig. 18. The skeleton of the head and trunk.

have not completely covered the brain. A baby's head, therefore, needs to be protected carefully from blows.

The ribs and sternum. The ribs are twelve pairs of slender bones that curve around the chest. They are used in breathing and they protect the heart and lungs. At the back they are attached to the spinal column. In front, the seven upper pairs are joined to the breastbone, or sternum^ and the next three pairs are hung from the ribs above. The two lower pairs have their front ends free, and are csW^d floating ribs.

The bones of the shoulder. The shoulder has two bones, — the collar-bone, or clavicle^ and the shoulder blade, or scapula. The scapula is a flat bone which lies on the back of the shoulder. It is held in place by strong muscles, and at its outer end has a socket for the head of the arm bone. The clavicle has its inner end attached to the sternum and its outer end is propped against the point of the scapula. When the clavicle is broken, as by a fall, the shoulder drops forward and downward.

The pelvis. The pelvic or hip bones are two large, widespreading, flat bones that can easily be felt in the sides. They are joined to the sacrum at the back and to each other in front. With the sacrum, these bones form the bowl-shaped pelvis, which gives support to the organs that lie in the lower part of the cavity of the abdomen and also furnishes a solid framework to which the legs are attached.

The bones of the limbs. Each limb has in it thirty bones, and the bones of the arm and leg are very similar. The thigh has in it a great bone called the femur, and the arm has in it a corresponding bone called the humerus. In the leg below the knee there are two

THE FRAMEWORK OF THE JIODV

«73

Fig. 19. From an X-ray photograph of a broken forearm and a wrist. The crosses show where the bones are broken.

long bones, the tibia and the fibicla, and in the forearm there are two similar bones, the tihia and the radius. In the wrist we find a group of small bones (the carpal bones), and in the ankle is another group of small bones (the tarsal bones). In the hand are five bones {metacarpals^ each bearing a finger, and in the foot are five bones {metatarsals^ each bearing a toe. Finally, the fingers of each hand have in them fourteen bones {phalanges), and the toes have the same number of bones arranged in the same way. The arms and legs are built on the same general plan, but the wrist has one more bone than the ankle, and the elbow has no bone corresponding to the kneecap {patella) on the front of the knee.

Bones composed of animal and mineral matter. A bone is composed of animal matter and mineral matter. The mineral matter is lime. The animal matter consists chiefly of tough fibers buried in the mineral groundwork of the bone. The animal matter gives the bone its toughness and keeps it from breaking. The mineral matter stiffens it and makes it able to bear the weight of the body.

These statements you can prove for yourself by burning one bone in the fire and soaking another in a weak acid. The first bone has the animal matter burned out of it and becomes brittle like chalk. The mineral matter is eaten out of the other bone by the acid, and the bone becomes limber like a piece of rubber tubing. You can easily imagine the difficulties you would be

1/4 in if your skeleton lacked either the mineral matter which stiffens it or the animal matter which toughens it.

Joints. Close your hand and watch your fingers as they bend. The bending is not in the bones themselves, but at the joints between the bones, and the advantage of having a jointed skeleton is that it makes movement possible. There are two principal kinds of joints in the body, — ball-and-socket joints and hinge joints. The former allow motion freely in any direction ; the latter allow motion only in two opposite directions, as does a hinge. Good examples of ball-and-socket joints are found in the shoulder and the hip ; of hinge joints, at the elbow, at the knee, and in the fingers.

Cartilage and ligaments. The ends of the bones at the joints are covered with a smooth, white material called cartilage^ which is kept moist by an oil that is secreted in the joints. This keeps down friction in the joints. Around the joints are many strong bands and cords of connective tissue called ligaments. Their chief function is to tie the bones together, but they also inclose the joints so that the oil cannot escape.

Figs. 20 and 21. On the left is shown the shoulder joint, an example of a ball-and-socket joint. On the right is the elbow joint, an example of a hinge joint.

Fig,

22. The ligaments of the wrist.

The treatment of sprains. When a joint is bent too far, the ligaments about it are either torn loose from the bones or broken. An injury of this kind is called a sprain, and a bad sprain often requires longer to heal than a broken bone. Some athletic trainers who are skilled in treating sprains insist that, if the joint can be properly supported, the injured member should be used as soon as possible. The reason given for this treatment is that exercise helps to keep up a good circulation through the part and also lessens the danger of the new ligaments being formed so short that the joint will be left stiff after the injured tissues have healed. It is difficult, however, to keep the parts from slipping about and breaking up the delicate new ligaments that are forming, and in most cases it is probably better to rest the injured part and exercise it only when this can be done without too great pain.