Physiology and Hygiene for Secondary Schools.

by Francis M. Walters, A.M.

PREFACE

The aim in the preparation of this treatise on the human body has been, first, to set forth in a _teachable_ manner the actual science of physiology; and second, to present the facts of hygiene largely as _applied physiology_. The view is held that "right living" consists in the harmonious adjustment of one's habits to the nature and plan of the body, and that the best preparation for such living is a correct understanding of the physical self. It is further held that the emphasizing of physiology augments in no small degree the educative value of the subject, greater opportunity being thus afforded for exercise of the reasoning powers and for drill in the _modus operandi_ of natural forces. In the study of physiology the facts of anatomy have a place, but in an elementary course these should be restricted to such as are necessary for revealing the general structure of the body.

Although no effort has been spared to bring this work within the comprehension of the pupil, its success in the cla.s.sroom will depend largely upon the method of handling the subject by the teacher. It is recommended, therefore, that the _relations_ which the different organs and processes sustain to each other, and to the body as a whole, be given special prominence. The pupil should be impressed with the essential unity of the body and should see in the diversity of its activities the serving of a common purpose. In creating such an impression the introductory paragraphs at the beginning of many of the chapters and the summaries throughout the book, as well as the general arrangement of the subject-matter, will be found helpful.

Since the custom largely prevails of teaching physiology in advance of the sciences upon which it rests-biology, physics, and chemistry-care should be exercised to develop correct ideas of the principles and processes derived from these sciences. Too much lat.i.tude has been taken in the past in the use of comparisons and ill.u.s.trations drawn from "everyday life." To teach that the body is a "house," "machine," or "city"; that the nerves carry "messages"; that the purpose of oxygen is to "burn up waste"; that breathing is to "purify the blood," etc., may give the pupil phrases which he can readily repeat, but teaching of this kind does not give him correct ideas of his body.

The method of teaching, however, that uses the pupil's experience as a basis upon which to build has a value not to be overlooked. The fact that such expressions as those quoted above are so easily remembered proves the value of connecting new knowledge with the pupil's experience. But _the inadequacy of this experience must be recognized_ and taken into account.

The concepts of the average pupil are entirely too indefinite and limited to supply the necessary _foundation for a science_ such as physiology.

Herein lies the great value of experiments and observations. They supplement the pupil's experience, and increase both the number and definiteness of his concepts. No degree of success can be attained if this phase of the study is omitted.

The best results in physiology teaching are of course attained where laboratory work is carried on by the pupils, but where this cannot be arranged, cla.s.s experiments and observations must suffice. The Practical Work described at the close of most of the chapters is mainly for cla.s.s purposes. While these serve a necessary part in the development of the subject, it is not essential that all of the experiments and observations be made, the intention being to provide for some choice on the part of the teacher. A note-book should be kept by the pupil.

To adapt the book to as wide a range of usefulness as possible, more subject-matter is introduced than is usually included in an elementary course. Such portions, however, as are unessential to a proper understanding of the body by the pupil are set in small type, to be used at the discretion of the teacher.

The use of books of reference is earnestly recommended. For this purpose the usual high school texts may be employed to good advantage. A few more advanced works should, however, be frequently consulted. For this purpose Martin's _Human Body_ (Advanced Course), Rettger's _Advanced Lessons in Physiology_, Thornton's _Human Physiology_, Huxley's _Lessons in Elementary Physiology_, Howell's _A Text-book of Physiology_, Hough and Sedgwick's _Hygiene and Sanitation_, and Pyle's _Personal Hygiene_ will be found serviceable.

In the preparation of this work valuable a.s.sistance has been rendered by Dr. C.N. McAllister, Department of Psychology, and by Professor B.M.

Stigall, Department of Biology, along the lines of their respective specialties, and in a more general way by President W.J. Hawkins and others of the Warrensburg, Missouri, State Normal School. Expert advice from Professor S.D. Magers, Instructor in Physiology and Bacteriology, State Normal School, Ypsilanti, Michigan, has been especially helpful, and many practical suggestions from the high school teachers of physiology of Kansas City, Missouri, Professor C.H. Nowlin, Central High School, Dr.

John W. Scott, Westport High School, and Professor A.E. Shirling, Manual Training High School, all of whom read both ma.n.u.script and proofs, have been incorporated. Considerable material for the Practical Work, including the respiration experiment (page 101) and the reaction time experiment (page 323), were contributed by Dr. Scott. Professor Nowlin's suggestions on subject-matter and methods of presentation deserve special mention. To these and many others the author makes grateful acknowledgment.

F.M.W.

MISSOURI STATE NORMAL SCHOOL, SECOND DISTRICT, May 1, 1909.

PHYSIOLOGY AND HYGIENE

PART I: THE VITAL PROCESSES

CHAPTER I - INTRODUCTION

To derive strength equal to the daily task; to experience the advantages of health and avoid the pain, inconvenience, and danger of disease; to live out contentedly and usefully the natural span of life: these are problems that concern all people. They are, however, but different phases of one great problem-the problem of properly managing or caring for the body. To supply knowledge necessary to the solution of this problem is the chief reason why the body is studied in our public schools.

*Divisions of the Subject.*-The body is studied from three standpoints: structure, use of parts, and care or management. This causes the main subject to be considered under three heads, known as anatomy, physiology, and hygiene.

_Anatomy_ treats of the construction of the body-the parts which compose it, what they are like, and where located. Its main divisions are known as gross anatomy and histology. _Gross anatomy_ treats of the larger structures of the body, while _histology_ treats of the minute structures of which these are composed-parts too small to be seen with the naked eye and which have to be studied with the aid of the microscope.

_Physiology_ treats of the function, or use, of the different parts of the body-the work which the parts do and how they do it-and of their relations to one another and to the body as a whole.

_Hygiene_ treats of the proper care or management of the body. In a somewhat narrower sense it treats of the "laws of health." Hygiene is said to be _personal_, when applied by the individual to his own body; _domestic_, when applied to a small group of people, as the family; and public, or _general_, when applied to the community as a whole or to the race.

*The General Aim of Hygiene.*-There are many so-called laws of health, and for these laws it is essential in the management of the body to find a common basis. This basic law, suggested by the nature of the body and conditions that affect its well-being, may be termed the _Law of Harmony: The mode of living must harmonize with the plan of the body_. To live properly one must supply the conditions which his body, on account of its nature and plan, requires. On the other hand, he must avoid those things and conditions which are injurious, _i.e._, out of harmony with the body plan. To secure these results, it is necessary to determine what is and what is not in harmony with the plan of the body, and to find the means of applying this knowledge to the everyday problems of living. Such is the general aim of hygiene. Stated in other words: Hygiene has for its general aim the bringing about of an essential harmony between the body and the things and conditions that affect it.(1)

*Relation of Anatomy and Physiology to the Study of Hygiene.*-If the chief object in studying the body is that of learning how to manage or care for it, and hygiene supplies this information, why must we also study anatomy and physiology? The answer to this question has already been in part suggested. In order to determine what things and conditions are in harmony with the plan of the body, we must know what that plan is. This knowledge is obtained through a study of anatomy and physiology. The knowledge gained through these subjects also renders the study of hygiene more interesting and valuable. One is enabled to see _why_ and _how_ obedience to hygienic laws benefits, and disobedience to them injures, the body.

This causes the teachings of hygiene to be taken more seriously and renders them more practical. In short, anatomy and physiology supply a necessary basis for the study of hygiene.

*Advantages of Properly Managing the Body.*-One result following the mismanagement of the body is loss of health. But attending the loss of health are other results which are equally serious and far-reaching.

Without good health, people fail to accomplish their aims and ambitions in life; they miss the joy of living; they lose their ability to work and become burdens on their friends or society. The proper management of the body means health, and it also means the capacity for work and for enjoyment. Not only should one seek to preserve his health from day to day, but he should so manage his body as to use his powers to the best advantage and prolong as far as possible the period during which he may be a capable and useful citizen.

CHAPTER II - GENERAL VIEW OF THE BODY

*External Divisions.*-Examined from the outside, the body presents certain parts, or divisions, familiar to all. The main, or central, portion is known as the _trunk_, and to this are attached the _head_, the _upper extremities_, and the _lower extremities_. These in turn present smaller divisions which are also familiar. The upper part of the trunk is known as the _thorax_, or chest, and the lower part as the _abdomen_. The portions of the trunk to which the arms are attached are the _shoulders_, and those to which the legs are joined are the _hips_, while the central rear portion between the neck and the hips is the _back_. The fingers, the hand, the wrist, the forearm, the elbow, and the upper arm are the main divisions of each of the upper extremities. The toes, the foot, the ankle, the lower leg, the knee, and the thigh are the chief divisions of each of the lower extremities. The head, which is joined to the trunk by the neck, has such interesting parts as the eyes, the ears, the nose, the jaws, the cheeks, and the mouth. The entire body is inclosed in a double covering, called the _skin_, which protects it in various ways.

*The Tissues.*-After examining the external features of the body, we naturally inquire about its internal structures. These are not so easily investigated, and much which is of interest to advanced students must be omitted from an elementary course. We may, however, as a first step in this study, determine what kinds of materials enter into the construction of the body. For this purpose the body of some small animal should be dissected and studied. (See observation at close of chapter.) The different materials found by such a dissection correspond closely to the substances, called _tissues_, which make up the human body. The main tissues of the body, as ordinarily named, are the _muscular_ tissue, the _osseous_ tissue, the _connective_ tissue, the _nervous_ tissue, the _adipose_ tissue, the _cartilaginous_ tissue, and the _epithelial_ and _glandular_ tissue. Most of these present different varieties, making all together some fifteen different kinds of tissues that enter into the construction of the body.(2)

*General Purposes of the Tissues.*-The tissues, first of all, _form the body_. As a house is constructed of wood, stone, plaster, iron, and other building materials, so is the body made up of its various tissues. For this reason the tissues have been called the _building materials_ of the body.

In addition to forming the body, the tissues supply the means through which its work is carried on. They are thus the _working materials_ of the body. In serving this purpose the tissues play an active role. All of them must perform the activities of growth and repair, and certain ones (the so-called active tissues) must do work which benefits the body as a whole.

*Purposes of the Different Tissues.*-In the construction of the body and also in the work which it carries on, the different tissues are made to serve different purposes. The osseous tissue is the chief substance in the bony framework, or skeleton, while the muscular tissue produces the different movements of the body. The connective tissue, which is everywhere abundant, serves the general purpose of connecting the different parts together. Cartilaginous tissue forms smooth coverings over the ends of the bones and, in addition to this, supplies the necessary stiffness in organs like the larynx and the ear. The nervous tissue controls the body and brings it into proper relations with its surroundings, while the epithelial tissue (found upon the body surfaces and in the glands) supplies it with protective coverings and secretes liquids. The adipose tissue (fat) prevents the too rapid escape of heat from the body, supplies it with nourishment in time of need, and forms soft pads for delicate organs like the eyeball.

*Properties of the Tissues.*-If we inquire how the tissues are able to serve such widely different purposes, we find this answer. The tissues differ from one another both in composition and in structure and, on this account, differ in their properties.(3) Their different properties enable them to serve different purposes in the body. Somewhat as gla.s.s is adapted by its transparency, hardness, and toughness to the use made of it in windows, the special properties of the tissues adapt them to the kinds of service which they perform. Properties that adapt tissues to their work in the body are called _essential_ properties. The most important of these essential properties are as follows:

1. Of osseous tissue, hardness, stiffness, and toughness. 2. Of muscular tissue, contractility and irritability. 3. Of nervous tissue, irritability and conductivity. 4. Of cartilaginous tissue, stiffness and elasticity. 5.

Of connective tissue, toughness and pliability. 6. Of epithelial tissue, ability to resist the action of external forces and power to secrete.

[Fig. 1]

Fig. 1-Hand and forearm, showing the grouping of muscular and connective tissues in the organ for grasping.

*Tissue Groups.*-In the construction of the body the tissues are grouped together to form its various divisions or parts. A group of tissues which serves some special purpose is known as an _organ_. The hand, for example, is an organ for grasping (Fig. 1). While the different organs of the body do not always contain the same tissues, and never contain them in the same proportions, they do contain such tissues as their work requires and these have a special arrangement-one adapted to the work which the organs perform.

In addition to forming the organs, the tissues are also grouped in such a manner as to provide supports for organs and to form cavities in which organs are placed. The various cavities of the body are of particular interest and importance. The three largest ones are the _cranial_ cavity, containing the brain; the _thoracic_ cavity, containing the heart and the lungs; and the _abdominal_ cavity, containing the stomach, the liver, the intestines, and other important organs (Fig. 2). Smaller cavities serving different purposes are also found.

[Fig. 2]

Fig. 2-Diagram of a lengthwise section of the body to show its large cavities and the organs which they contain.

*Organs and Systems.*-The work of the body is carried on by its various organs. Many, in fact the majority, of these organs serve more than one purpose. The tongue is used in talking, in masticating the food, and in swallowing. The nose serves at least three distinct purposes. The mouth, the arms, the hands, the feet, the legs, the liver, the lungs, and the stomach are also organs that serve more than one purpose. This introduces the principle of economy into the construction of the body and diminishes the number of organs that would otherwise be required.

The various organs also _combine_ with one another in carrying on the work of the body. An ill.u.s.tration of this is seen in the digestion of the food-a process which requires the combined action of the mouth, stomach, liver, intestines, and other organs. A number of organs working together for the same purpose form a _system_. The chief systems of the body are the digestive system, the circulatory system, the respiratory system, the muscular system, and the nervous system.