The human body and health, revised; an intermediate textbook of essential physiology, applied hygiene, and practical sanitation for schools

I. I

HUMAN BODY AND HEALTH

REVISED

AN INTERMEDIATE TEXTBOOK OF ESSENTIAL PHYSIOLOGY, APPLIED HYGIENE, AND PRACTICAL SANITATION FOR SCHOOLS

BY

ALVIN DAVISON, M.S., A.M., Ph.D.

INTERMEDIATE

AMERICAN BOOK COMPANY

NEW YORK CINCINNATI CHICAGO

BOSTON

ATLANTA

. 3^3

Copyright, 1909 , by ALVIN DAVISON.

Copyright, 1924 , by AMERICAN BOOK COMPANY.

HUMAN body, revised. INT.

W. P. I

I

MADE IN U.S.A.

Preface

A few minutes* reflection in regard to the modern ways of living will fix in the mind of any sound reasoner the con¬ viction that we are a careless and cruel people. Nearly 1000 human beings in the United States are dying daily of diseases which science has shown how to prevent. Streams are polluted, garbage dumped on the nearest vacant lot, fresh air and sunshine shut out of the houses by double doors and windows, and innocent children fed dirty milk because people do not realize that these acts are respon¬ sible for many of the 4000 graves daily made in our nation’s cemeteries.

Sanitary science and the public health can be advanced only as they are supported by an intelligent public opinion. Laws necessary to the public welfare can be secured and up¬ held when the majority of citizens appreciate the value of the problems involved. New ideas are grasped most readily by the young and it is with them that modem hygienic teaching will have the greatest influence. Parents do not recognize that eyesight is being impaired, normal growth prevented, blood poisoned, and the body starved because of customs and habits born in ignorance.

An effort has been made to present in this book the sub¬ ject of personal and public health in such a way as to appeal to the interest of boys and girls and fix in their minds the essentials of right living. Knowing anatomy and physiology is of little value to our young folks unless it helps them to practice intelligently in their daily lives the teachings of hygiene and sanitation.

In place of general statements in regard to promoting health, specific facts and full explanations are given showing

PREFACE how disease is caused and how the body may be kept well and strong. Much labor and expense have been devoted to the preparation of the illustrations which the pupils should be required to study carefully.

A few experiments have been outlined and many other experiments and helpful suggestions for the teacher are given in the Advanced book- of this series. The im¬ portance of proving the truth and making clear the leading facts relating to efficient living, by simple demonstrations and experiments cannot be overestimated.

Every teacher is urged to secure from the State Board of Health, at the capital of the state, copies of the numerous bulletins issued concerning health. These are sent free to those requesting them. The teacher who does her duty in imparting instruction that invites health and happiness will bless not only those of to-day, but generations yet unborn.

How the Body is Gc v^erned

•

•

XVII. The Care of the Nervous System

coTics Affect it

AND HOW NaR-

CONTENTS

CHAPTER PAGE

XVIII. Organs for Receiving Knowledge ^ . 174

XIX. The Cause of Sickness ..... 188

XX. How TO Keep Well ..... 200

Pronunciation and Explanation of Difficult

THE HUMAN BODY AND HEALTH

Chapter I The Human Body As A Living Machine

The Body like a Locomotive.—^The locomotive moves about and does work at the bidding of the engineer. It does this just as long as it is supplied with water, and coal or wood, if the ashes, the burnt waste matters, are re¬ moved, and if its parts are kept in order.

No engineer is trusted to manage a locomotive until he understands all its parts and how they work. To avoid wrecks and loss of life, he must examine his machine at the end of every trip and see that every screw, lever and wheel is in proper order.

The human body is in many ways like the locomotive and each person is his own engineer. The body does what its owner commands as long as it is fed, if the ashes, the waste matters, are removed and if its parts are kept in a healthy condition.

Why One should know the Parts of the Body.—No rail¬ road company will trust the management of a locomotive to an engineer who does not know its parts, because by the neglect to repair a weak or worn part the entire engine may be ruined. For the same reason every person, who is the engineer of his own body, should know its parts.

10 THE HUMAN BODY AS A LIVING MACHINE

The study of the parts of the body and their location is called anatomy. The greatest use of anatomy is to help one to understand how the parts of the body do their work.

Learning the Use of the Parts.—The engineer must understand the use of each lever, wheel and screw in his engine in order to determine when they are in proper work¬ ing condition. A person must likewise know the use of the various parts of his body to understand when they are doing their work properly.

The use of any certain portion of the body is spoken of as its function. The study of the function of the heart, lungs or other parts of the body is known as physiology.

One of the chief benefits to be had from the study of physiology is the knowledge which aids us much in under¬ standing how to care for the body. By proper care all its parts may be kept in a healthy state and in most cases sickness may be prevented.

Taking Care of the Body.—The body is a much more delicate machine than the locomotive. It is often injured by food taken at the wrong time, or in too large quantities. Impure oil and dirty coal sometimes clog parts of the locomotive and make it do poor work. Impure air and unclean food and water often seriously damage the human body so as to cause sickness and even death.

The study of the care of the body and of how to prevent fevers, colds and ill health of all sorts is called hygiene. Happiness and health depend largely upon hygiene.

Importance of Hygiene.—During the eighteenth century, it is estimated that 50,000,000 persons died of sm.allpox

THE HUMAN BODY AS A LIVING MACHINE in Europe. To-day the disease is so uncommon that many physicians have never seen a case.

Scurvy which afflicted so many of the sailors a century or two ago now seldom occurs because the men have learned what kind of food to eat to avoid the disease. Of the French soldiers who went to fight the people of Mada¬ gascar, seven thousand died of fevers which we now know how to prevent, and only twenty-nine were killed in battle. In our war with Spain, less than three hundred of our soldiers were killed in battle, but over three thousand died of disease which hygiene has shown how to avoid.

What Hygiene does.—Hygiene protects the body in time of peace as the shield and steel armor of the old Romans protected them in time of war. Health depends largely upon preventing tiny plants and animals called germs, from feeding upon our bodies, and upon supplying the body with the proper food, air, drink and clothing.

Among every thousand people there are more than twice as many deaths yearly in Russia and India as in Sweden. This is because the Russians and people of India do not observe the teachings of hygiene so carefully as the Swedes. In London, a hundred years ago, the number of deaths in every thousand residents was three times as great as in the year 1900.

Why All should know Hygiene.—In order that we may be a healthy nation, every one must observe the laws of hygiene. Each person by his own efforts alone may not be able to protect his health, for the ignorant may furnish him bad food or bad water. A milkman caused 236 cases of diphtheria in one city by being so careless as to help care

THE HUMAN BODY AS A LIVING MACHINE for the milk when he was recovering from diphtheria. One hundred years ago, the average length of human life in the United States was 28 years. Hygiene has shown us how to prevent sickness and death so that the average length of life is now 42 years.

1600-1700

1700-1800

1800-1850 igooigoo

igio

15 acres

14 acres

13 acres

nacres

aacres

racres

Fig. 1 —Number of acres required yearly to bury the dead among each 1,000,000 inhabitants in Germany, England and the United States. Note that the number of deaths is decreasing as people learn how to avoid disease.

1. In what way is the body like a locomotive? 2. Why should a person know much about his body? 3. What is meant by anatomy? 4. Of what use is anatomy? 5. Why should you know the use of the parts of the body? 6. What is physiology? 7. How does the study of physiology benefit one? 8. Describe what is meant by hygiene? 9. Name some diseases which long ago killed many. 10. Upon what does health depend? 11. Why do more people die in some countries than in others? 12. Why can one not pro¬ tect his health by his efforts alone? 13. How can we secure the best health as a nation?

Chapter II

Bacteria.—Bacteria are also called microbes or germs. There are hundreds of kinds of bacteria and all are so small that a million together would not make a mass so large as the head of a pin. They are of various shapes. Most of them are straight, curved, or twisted rods. Some have the form of a ball.

Bacteria occur nearly everywhere. A bit of dirt as large as a pea may contain a million bacteria, and a hundred thousand of them are commonly present in a cup of water. More than a million bacteria are lodged on the surface of the body and billions dwell in the mouth and intestine.

Many kinds of bacteria are useful, but a few kinds some¬ times cause serious disease when they grow in other plants, or in the bodies of animals or man.

Nature of Bacteria.—A hundred years ago many people thought that dead matter could of itself change into living plants or animals. When meat broth is put away in the cupboard for a day or two, the microscope shows it to be full of tiny forms of life. It is now known that this life does not start from the broth, but consists of

14 PLANTS AND ANIMALS RP^LATED TO HEALTH bacteria. They are constantly floating through the air and can be kept out of food by placing it in air¬ tight jars. The food and the jars must first be boiled to kill the bacteria in them.

The spoiling or souring of food of any kind is generally due to bacteria.

Need of Bacteria.—Experi¬ ment shows that higher life depends upon the help of bacteria. The dead leaves, grass, fallen trees and the waste matter of the barnyard cannot rot or decay without the aid of bacteria. If these little plants were destroyed, the surface of the earth would soon become cov¬ ered with dead matter.

These ever-present bacteria change the dead plants and animals

Fig. 2. —Harmless bacteria so numerous in drinking water that a person often takes a half-million into his stomach daily. Much enlarged.

products of life into a food which matter into food for the grass, wheat and corn. Much enlarged.

the new plants can use the next season. Some bac¬ teria feed upon living animals instead of dead matter. It is these that cause disease.

Bacteria of Disease.—Fifty million persons are every year forced to the sick bed in this country and Europe by bacteria. Each disease is caused by a certain kind of germs and if these are kept out of the body, the sickness cannot occur.

Some of the common diseases resulting from bacteria are pneumonia, measles, typhoid fever, diphtheria, sore throat, sore throat diphtheria sleeping sickness boils leprosy grippe malaria

PiQ. 4.—The germs causing various diseases. Much enlarged.

grippe and tuberculosis. When the germs of these diseases get into the body, they devour the tissues and give off poisons.

How Bacteria get into the Body.—^Bacteria nearly always enter the body through the mouth. The germs of typhoid fever generally reach the system with water which has received the waste matter from a typhoid patient. The bacteria of pneumonia, sore throat, diphtheria and grippe are frequently received from the drinking cup, pencils oi other objects used by persons recently recovered from these diseases. The germs are sometimes breathed in with dust. The bacteria of tuberculosis reach the body with air or food or are scraped from the drinking cup or other objects used by the sick.

If nurses and patients would be careful to destroy with boiling water or formalin the germs which leave the bodies of the sick in the spit and other excretions, there would be fewer bacteria to make people sick.

How Bacteria grow.—When supplied with food and kept warm, bacteria grow very rapidly. Cold makes them grow more slowly. One plant produces two new ones by separa¬ ting in the middle. This can occur every fifteen minutes so

that one germ can produce millions in a single

Fig. 5.—Drawing of a germ at inter- day.

vals of ten minutes while growing. i . ,

In some bacteria de¬ prived of food and moisture, the contents of the plant col¬ lect in one part and become surrounded by a tough coat. This part with its coat is a spore. Boiling water will kill most spores in less than ten minutes. Our common disease bacteria do not have spores and therefore they are killed by being boiled one minute.

Mold.—Mold belongs to the group of plants known as fungi. They have no light green coloring matter in them and cannot feed on the air as plants with green leaves do.

Mold often forms white or greenish patches on bread or fruit in a damp cellar. It is made of fine threads from

Fig. 6.—Bac¬ teria. The white bodies are spores.

Fig. 7. —Bread mold much enlarged. Note the tiny spores bursting from their case in the right upper corner.

which other hairlike branches stick, up into the air.

These branches bear on their ends little knobs contain¬

ing dozens of tiny balls called spores.

These spores break loose and float about in the dust. When they fall upon moist food they sprout and grow into a patch

of mold. The spores are hard to kill but eight minutes in boil¬ ing water will usually cause their death.

Some kinds of mold grow on the body and cause disease. Barber's itch and ringworm are caused by molds growing in the skin. The spores are carried from one face to another by an uncleaned razor, towel, or brush. Other diseases are sometimes caught by using soiled towels in public places.

Animal Parasites.—Any plant or animal which feeds upon another living plant or animal without at once destroying it, is a parasite.

The bacteria of disease are all para¬ sites. Some animals live in the human body and produce disease. Yellow fever, sleeping sickness, and malaria are caused by tiny animals which get into the body by the bite of a fly or mosquito. The plague which has killed

Fig. 8.—A flea which car¬ ries the germs of plague from the sick to the well.

DAY. PHTS. INT.-2 millions of people in Asia and some in our own country is caused by bacteria, but the germs are usually put beneath the skin by the bite of bugs or fleas which have been sucking blood from sick persons or from rats.

The Itch Mite and Head Lice.—The itch was once a very common disease. When it was discovered that a little spider living in the skin was the cause of the continuous itching, a way of killing it was soon found (Fig. 9).

The disease is now easily cured by an ointment which any physician can supply.

Tiny six-legged insects called head lice some¬ times live among the hair. They cause con¬ tinuous itching and sleep¬ lessness. They are easily killed by thoroughly rub¬ bing the scalp with equal ^ parts of olive oil and coal oil before going to bed.

Fig. 9.—The tiny spider which causes the itch when living in the skin. Much enlarged.

The hair should then be kept from soiling the linen by wrap¬ ping a towel about the head. In the morning the head should be washed with soap and equal parts of vinegar and hot water to remove the tiny white eggs clinging to the hair. This treatment should be given two or three times.

Worms. —Small worms also may be parasites in the human body. There are various kinds like the tapeworm and roundworm, but the most important is the hookworm. This is found in the ground in the southern states, and enters through the skin when a person goes barefoot.

The parasite finally reaches the intestine and so weakens the individual that he loses all energy, becomes shiftless, ane¬ mic, and dull. A doctor can give drugs which will expel the worms and bring about complete re¬ covery.

Overcoming the Para¬ sites. —Owing to the fact that many sick per¬ sons through carelessness let disease germs escape from their bodies, every¬ body is likely to get some of these enemies into his body. The studies of physiology and hygiene have shown that persons may prevent many of them from entering the body or even from growing after they are in the body. Prevention of the sickness which they cause, as well as of other kinds of sickness, depends much upon understanding the plan of the body, the care and use of food, and the care and use of the organs as explained in the following chapters.

Fig. 10.—The boy at the left is a victim of the hookworm disease. He is 21 years old and weighs 65 pounds. The other boy is not infected. He is 10 years old and weighs 63 pounds.

1. Give two other names for bacteria. 2. What is the form of bacteria? 3. Where are bacteria found? 4. When may bacteria be harmful? 5. How may bacteria be kept away from food? 6. Of what use are some bacteria? 7. State a fact showing that bacteria cause much sickness. 8. Name some diseases due to bacteria.

9. How do tlie germs of typhoid fever often get into the body?

10. State how the bacteria of other diseases may enter the body.

11. What should nurses and patients do to prevent sickness in other persons? 12. Describe how bacteria grow. 13. What is a spore? 14. Why are some bacteria harder to kill than others? 15. Describe mold. 16. What kinds of mold cause disease? 17. What is a parasite? 18. Name some diseases caused by tiny animals living in the body. 19. WTiy should one having itch not sit near or handle things to be used by other persons? 20. Why should one with head lice not use another, person’s brush or hat? 21. How is the hookworm disease contracted? 22. How can we prevent sickness from parasites?

The presence of mold germs in dust may easily be shown in the following manner: Rub a piece of bread across one board of a dusty floor and then lay it soiled-side up in a saucer containing two table¬ spoonfuls of water. Cover with a bowl and let it remain in a warm place from three to six days. The white threads of mold may then be seen and on the ends of the upright branches are tiny balls each containing a hundred or more spores.

Chapter III The Plan Of The Human Bodt

Nature of Living Things.—Liv¬ ing plants and animals differ from all dead objects such as iron and stone by being able to take food and change it so as to form a part of their own bodies.

The corn plant takes in some of its food through the leaves and some through the roots. In some of the worms and other lower ani¬ mals, the food in a watery state passes directly through the skin into the body. Most animals, however, have a special open¬ ing called the mouth for the pur¬ pose of receiving food, and a sac or canal in which the food is changed to a liquid. Then there are tubes for taking the food to all parts of the body and for car¬ rying off the waste matter.

Special structures are provided for moving the body, and there are still other structures called nerves to make all parts of the body work in proper order.

These several duties such as

Fig. 11.—The chief organs of the body from the side, o, arch of the aorta or main artery of the trunk; c, large intestine; d, diaphragm; e, throat; g, lung; k, kidney; I, spinal cord within the back bone; m, main artery dividing to go to the legs; n, pancreas; o, gullet; 4, spleen; tr, wind pipe; f,main vein of body; ap, appendix.

preparing food, carrying it about in the body and moving the body, are performed by separate portions of the human body, which are named systems.

The Systems.— We shall study seven systems forming the human body. The framework or hony system is for support and movement. The lean meat makes up much of the muscular system used in moving the bones. The mouth, stomach, intestine and whatever else helps to prepare the food for use form the digestive system. The blood tubes, conveying the food from the intestine to all parts of the body and carrying off the waste matter, constitute the hlood system.

Fig. 12.—Slice of the wall of the gullet enlarged to show nature of tissues.

The breathing system con¬ sists of the lungs and other parts used in supplying the body with air. The skin and kidneys taking the waste matter out of the blood belong to the sewer system. The brain and nerves form the nervous system which directs the ac¬ tions of all parts of the body.

The Parts of a System.

—Each system is com¬ posed of several parts called organs. Each organ has a certain work to do in helping the body to keep well and perform the duties of life. The heart is the organ for sending the blood through the body, the stomach is an organ for digesting food, and a lung is an organ for breathing.

Nature of an Organ.—The organs when examined with a microscope enlarging their parts are seen to be made of several different substances. Each of these is called a tissue. The stomach, is lined with one kind of tissue wnile its outer part is made of muscular tissue (Fig. 12.) Among these two is a nervous tissue, and the three are bound together by a connective tissue made mostly of fine threads.

Parts of a Tissue.

—The microscope shows that the tis¬ sues are made of cells mingled with fine threads or other substance. A cell is a tiny mass of matter containing a smaller particle of matter called the nucleus. Usually each cell is surrounded by a thin membrane, the cell wall (Fig. 13).

The form of cells varies widely. The fat cells are like little balls while the muscle cells are rodlike. The nerve cells are very irregular with branching processes. Some of the cells such as those on the surface of the skin are flat like the scales of a fish and others in the intestine are shaped like tiny corks.

Character of Cells.—All plants and animals are composed of one or more cells united by threadlike fibers, or by other matter. Each of many plants and animals living in dirty

Fig. 14.—Various kinds of cells many times enlarged, n, from the brain; /, fat cell; m, muscle; e, surface of skin.

water is made of a single cell. They require food and air just the same as the cells of the body and also give off waste matter.

After growing to a certain size, these animals

Fig. 15 .—A water snake which has just divide in the mid¬ shed its outer skin. die and each half

swims away as a new animal to repeat the process the next day. In the same way new cells are formed in the body, but instead of moving apart they stick fast together.

Dying Parts of the Body.—Dead cells can be scraped from the sldn at any time. Some animals such as frogs and snakes shed the entire dead outer skin in one piece several times each year. The cells beneath divide and thus form other cells for a new skin.

The cells within the deep parts of the body remain m place year after year, but tiny bits of them are dying con¬ stantly and passing out in the breath, the sweat and in other ways. These dead bits are burned to ashes in the body in much the same way that a match burns. The burning of anything means the union with it of a part of the air called oxygen.

Burning or Oxidation.—The union of oxygen with any other substance is oxidation. The head of a match is scratched to make it hot enough to cause the oxygen of the air to unite with it.

The living action of the cells in the body makes the oxygen there unite with the dead particles and burn them into ashes so that they can be carried out of the body through the lungs and kidneys, and not clog the organs. This burning or oxidation of the dead parts of the cells, and of the food brought there by the blood, goes on very slowly so there is no flame but enough heat to keep the body warm. By experiment, it has been found that the oxidation of an ounce of fat within the body furnishes just the same amount of heat as the burning of an ounce of fat produces when burned outside of the body.

1 . How does dead matter differ from living things? 2. What animals do not have mouths? 3. What is a system in the body? 4. Name some of the systems in the body. 5. Tell what three of the systems are used for. 6. What is an organ? 7. Name five organs in the body. 8. What is a tissue? 9. Tell how the cells differ. 10. How do cells grow? 11. How are the dying parts of the body cast off? 12. What is oxidation? 13. What makes oxidation occur in the body? 14. What results from oxidation in the body? 15. Where is oxygen burned in the body?

The fact that parts of the body are dying and are being cast off may be shown in the following manner: Secure two or three frogs, or salamanders found in ponds or under stones near streams and place them in a jar containing a half inch of water. Generally with¬ in a week, large strips of shed skin may be seen floating in the water. The shed skins of caterpillars or other insects may often be found sticking to stones or trees. Any caterpillar confined in a box and fed for a few days with the leaves of the plant on which it was found will shed its skin.

Chapter IV

Need of Food.—The body consists of about twelve gallons of water; twelve pounds of mineral matter such as table salt, potash, lime and iron; twelve pounds of fat; and twenty-four pounds of proteid. Proteid forms a portion of every cell in the body. A common form of proteid is albumin like the white of egg. Since mineral matter such as lime,

\ , salt and potash left from burning the piece

parts of the body of meat, a.

made of these sub¬ stances are dying daily and passing away, such food must be taken as will restore the loss.

Food is also required for fuel to be burned to keep the body warm, and to supply energy to make it move and enable the organs to do their work. A steam locomotive cannot pull cars without burning coal. For the same reason, the arm or leg cannot be moved without some thing being burned in the body.

Kinds of Food.—The two gener&l groups of foods are

the flesh foods and the fuel foods. The flesh foods are the proteids. These form a large part of lean meat, of dried peas and beans, and of wheat flour. They help build up bone, blood, and flesh.

The/iie^ foods consist of sugars, starches, and fats. These are used to give energy for work and to keep the body

warm. The sugar used on the table i s made largely from beets and from sugar cane.

Milk sugar is pres¬ ent in milk, and fruit sugar makes the ripe fruit sweet.

Starch is found mainly in such vege- Fig. 18.—A tiny slice of potato to show the tables as COrn starch grains. Much enlarged. . , ,

rice, wheat, and

potatoes, where it appears in the form of little grains (Fig.

Fats make up most of the fat meat, form a large part of the cream of milk and about nine tenths of butter. The fat of beef is called tallow and that from pork is known as lard. A fat which is liquid at room temperature is spoken of as oil. Cottonseed oil, castor oil and olive oil are de¬ rived from plants.

Quantity of Food Required.—Careful experiments lately made have shown that most people eat too much. No matter how much food is eaten, only that part of it re¬ quired by the body for replacing worn-out material and furnishing fuel will be used. The extra amount eaten is likely to cause sickness by clogging the organs or by help¬ ing bacteria to develop in the food canal and to give off poisons. These produce headache and other kinds of illness called indigestion or dyspepsia.