Hygienic Physiology : with Special Reference to the Use of Alcoholic Drinks and Narcotics

Part 4

Chapter 43,838 wordsPublic domain

TIME FOR EXERCISE.--We should not exercise after long abstinence from food, nor immediately after a meal, unless the meal or the exercise be very light. There is an old-fashioned prejudice in favor of exercise before breakfast--an hour suited to the strong and healthy, but entirely unfitted to the weak and delicate. On first rising in the morning, the pulse is low, the skin relaxed, and the system susceptible to cold. Feeble persons, therefore, need to be braced with food before they brave the outdoor air.

WHAT KIND OF EXCERCISE TO TAKE.--For children, games are unequaled. Walking, the universal exercise, [Footnote: The custom of walking, so prevalent in England, has doubtless much to do with the superior physique of its people. It is considered nothing for a woman to take a walk of eight or ten miles, and long pedestrian excursions are made to all parts of the country. The benefits which accrue from such an open-air life are sadly needed by the women of our own land. A walk of half a dozen miles should be a pleasant recreation for any healthy person.] is beneficial, as it takes one into the open air and sunlight. Running is better, since it employs more muscles, but it must not be pushed to excess, as it taxes the heart, and may lead to disease of that organ. Rowing is more effectual in its general development of the system. Swimming employs the muscles of the whole body, and is a valuable acquirement, as it may be the means of saving life. Horseback riding is a fine accomplishment, and refreshes both mind and body. Gymnastic or calisthenic exercises bring into play all the muscles of the body, and when carefully selected, and not immoderately employed, are preferable to any other mode of indoor exercise. [Footnote: The employment of the muscles in exercise not only benefits their especial structure, but it acts on the whole system. When the muscles are put in action, the capillary blood vessels with which they are supplied become more rapidly charged with blood, and active changes take place, not only in the muscles, but in all the surrounding tissues. The heart is required to supply more blood, and accordingly beats more rapidly in order to meet the demand. A larger quantity of blood is sent through the lungs, and larger supplies of oxygen are taken in and carried to the various tissues. The oxygen, by combining with the carbon of the blood and the tissues, engenders a larger quantity of heat, which produces an action on the skin, in order that the superfluous warmth may be disposed of. The skin is thus exercised, as it were, and the sudoriparous and sebaceous glands are set at work. The lungs and skin are brought into operation, and the lungs throw off large quantities of carbonic acid, and the skin large quantities of water, containing in solution matters which, if retained, would produce disease in the body. Wherever the blood is sent, changes of a healthful character occur. The brain and the rest of the nervous system are invigorated, the stomach has its powers of digestion improved, and the liver, pancreas, and other organs perform their functions with more vigor. By want of exercise, the constituents of the food which pass into the blood are not oxidized, and products which produce disease are engendered. The introduction of fresh supplies of oxygen induced by exercise oxidizes these products, and renders them harmless. As a rule, those who exercise most in the open air will live the longest.--LANKESTER.] (See p. 280.)

THE WONDERS OF THE MUSCLES.--The grace, ease, and rapidity with which the muscles contract are astonishing. By practice, they acquire a facility which we call mechanical. The voice may utter one thousand five hundred letters in a minute, yet each requires a distinct position of the vocal organs. We train the muscles of the fingers till they glide over the keys of the piano, executing the most exquisite and difficult harmony. In writing, each letter is formed by its peculiar motions, yet we make them so unconsciously that a skillful penman will describe beautiful curves while thinking only of the idea that the sentence is to express. The mind of the violinist is upon the music which his right hand is executing, while his left determines the length of the string and the character of each note so carefully that not a false sound is heard, although the variation of a hair's breadth would cause a discord. In the arm of a blacksmith, the biceps muscle may grow into the solidity almost of a club; the hand of a prize fighter will strike a blow like a sledge hammer; while the engraver traces lines invisible to the naked eye, and the fingers of the blind acquire a delicacy that almost supplies the place of the missing sense.

DISEASES, ETC.--l. _St. Vitus's Dance_ is a disease of the voluntary muscles, whereby they are in frequent, irregular, and spasmodic motion beyond the control of the will. All causes of excitement, and especially of fear, should be avoided, and the general health of the patient invigorated, as this disease is closely connected with a derangement of the nervous system.

2. _Convulsions_ are an involuntary contraction of the muscles. Consciousness is wanting, while the limbs may be stiff or in spasmodic action. (See p. 261.)

3. _Locked-jaw_ is a disease in which there are spasms and a contraction of the muscles, usually beginning in the lower jaw. It is serious, often fatal, yet it sometimes follows as trivial an injury as the stroke of a whip lash, the lodgment of a bone in the throat, a fishhook in the finger, or a tack in the sole of the foot.

4. _Gout_ is characterized by an acute pain located chiefly in the small joints of the foot, especially those of the great toe, which become swollen and extremely sensitive. It is generally accompanied by an excess of uric acid in the blood, and a deposit of urate of soda about the affected joint. Gout is often the result of high living, and of too much animal food. It is frequently inherited.

5. _Rheumatism_ affects mainly the connective, white, fibrous tissue of the larger joints. While gout is the punishment of the rich who live luxuriously, rheumatism afflicts alike the poor and the rich. There are two common forms of rheumatism--the inflammatory or acute, and the chronic. The latter is of long continuance; the former terminates more speedily. The acute form is probably a disease of the blood, which carries with it some poisonous matter that is deposited where the fibrous tissue is most abundant. The disease flies capriciously from one joint to another, and the pain caused by even the slightest motion deprives the sufferer of the use of the disabled part and its muscles. Its chief danger lies in the possibility of its affecting the vital organs. Chronic rheumatism--the result of repeated attacks of the acute--leads to great suffering, and oftentimes to disorganization of the joints and an interference with the movements of the heart.

6. _Lumbago_ is an inflammation of the lumbar muscles and fascia. [Footnote: Lumbago is really a form of myalgia, a disease which, has its seat in the muscles, and may thus affect any part of the body. Doubtless much of what is commonly called "liver" or "kidney complaint" is only, in one case, myalgia of the chest or abdominal walls near the liver, or, in the other, of the back and loins near the kidneys. Chronic liver disease is comparatively rare in the Northern States, and pain in the side is not a prominent symptom; while certain diseases of the kidneys, which are as surely fatal as pulmonary consumption, are not attended by pain in the back opposite these organs.--WEY.] It may be so moderate as to produce only a "lame back," or so severe as to disable, as in the case of what is popularly termed a "crick in the back." Strong swimmers who sometimes drown without apparent cause are supposed to be seized in this way.

7. _A Ganglion_, or what is vulgarly called a "weak" or "weeping" sinew, is the swelling of a bursa. [Footnote: A bursa is a small sack containing a lubricating fluid to prevent friction where tendons play over hard surfaces. There is one shaped like an hourglass on the wrist, just at the edge of the palm. By pressing back the liquid it contains, this bursa may be clearly seen.] It sometimes becomes so distended by fluid as to be mistaken for bone. If on binding something hard upon it for a few days it does not disappear, a physician will remove the liquid by means of a hypodermic syringe, or perhaps cause it to be absorbed by an external application of iodine.

PRACTICAL QUESTIONS.

1. What class of lever is the foot when we lift a weight on the toes?

2. Explain the movement of the body backward and forward, when resting upon the thigh bone as a fulcrum.

3. What class of lever do we use when we lift the foot while sitting down?

4. Explain the swing of the arm from the shoulder.

5. What class of lever is used in bending our fingers?

6. What class of lever is our foot when we tap the ground with our toes?

7. What class of lever do we use when we raise ourselves from a stooping position?

8. What class of lever is the foot when we walk?

9. Why can we raise a heavier weight with our hand when lifting from the elbow than from the shoulder?

10. What class of lever do we employ when we are hopping, the thigh bone being bent up toward the body and not used?

11. Describe the motions of the bones when we are using a gimlet.

12. Why do we tire when we stand erect?

13. Why does it rest us to change our work?

14. Why and when is dancing a beneficial exercise?

15. Why can we exert greater force with the back teeth than with the front ones?

16. Why do we lean forward when we wish to rise from a chair?

17. Why does the projection of the heel bone make walking easier?

18. Does a horse travel with less fatigue over a flat than a hilly country?

19. Can you move your upper jaw?

20. Are people naturally right or left-handed?

21. Why can so few persons move their ears by the muscles?

22. Is the blacksmith's right arm healthier than the left?

23. Boys often, though foolishly, thrust a pin into the flesh just above the knee. Why is it not painful?

24. Will ten minutes' practice in a gymnasium answer for a day's exercise?

25. Why would an elastic tendon be unfitted to transmit the motion of a muscle?

26. When one is struck violently on the head, why does he instantly fall?

27. What is the cause of the difference between light and dark meat in a fowl?

III.

THE SKIN.

A protection from the outer world, it is our only means of communicating with it. Insensible itself, it is the organ of touch. It feels the pressure of a hair, yet bears the weight of the body. It yields to every motion of that which it wraps and holds in place. It hides from view the delicate organs within, yet the faintest tint of a thought shines through, while the soul paints upon it, as on a canvas, the richest and rarest of colors.

ANALYSIS OF THE SKIN.

THE SKIN.

THE SKIN is a tough, thin, close-fitting garment for the protection of the tender flesh. Its perfect elasticity beautifully adapts it to every motion of the body. We shall learn hereafter that it is more than a mere covering, being an active organ, which does its part in the work of keeping in order the house in which we live. It oils itself to preserve its smoothness and delicacy, replaces itself as fast as it wears out, and is at once the perfection of use and beauty.

1. STRUCTURE OF THE SKIN.

CUTIS AND CUTICLE.--What we commonly call the skin--viz., the part raised by a blister--is only the cuticle [Footnote: _Cuticula_, little skin. It is often styled the scarfskin, and also the epidermis (_epi_, upon; and _derma_, skin).] or covering of the cutis or true skin. The latter is full of nerves and blood vessels, while the former neither bleeds [Footnote: We notice this in shaving; for if a razor goes below the cuticle, it is followed by pain and blood. So insensible is this outer layer that we can run a pin through the thick mass at the roots of the nails without discomfort.] nor gives rise to pain, neither suffers from heat nor feels the cold.

The cuticle is composed of small, flat cells or scales. These are constantly shed from the surface in the form of scurf, dandruff, etc., but are as constantly renewed from the cutis [Footnote: We see how rapidly this change goes on by noticing how soon a stain of any kind disappears from the skin. A snake throws off its cuticle entire, and at regular intervals.] below.

Under the microscope, we can see the round cells of the cuticle, and how they are flattened and hardened as they are forced to the surface. The immense number of these cells surpasses comprehension. In one square inch of the cuticle, counting only those in a single layer, there are over a billion horny scales, each complete in itself.--HARTING.

FIG. 22.

VALUE OF THE CUTICLE.--In the palm of the hand, the sole of the foot, and other parts especially liable to injury, the cuticle is very thick. This is a most admirable provision for their protection. [Footnote: We can hold the hand in strong brine with impunity, but the smart will quickly tell us when there is even a scratch in the skin. Vaccine matter must be inserted beneath the cuticle to take effect. This membrane doubtless prevents many poisonous substances from entering the system.] By use, it becomes callous and horny. The boy who goes out barefoot for the first time, "treading as if on eggs," can soon run where he pleases among thistles and over stones. The blacksmith handles hot iron without pain, while the mason lays stones and works in lime, without scratching or corroding his flesh.

THE COMPLEXION.--In the freshly made cells on the lower side of the cuticle, is a pigment composed of tiny grains. [Footnote: These grains are about 1/2000 of an inch in diameter, and, curiously enough, do not appear opaque, but transparent and nearly colorless.--MARSHALL.] In the varying tint of this coloring matter, lies the difference of hue between the blonde and the brunette, the European and the African. In the purest complexion, there is some of this pigment, which, however, disappears as the fresh, round, soft cells next the cutis change into the old, flat, horny scales at the surface.

Scars are white, because this part of the cuticle is not restored. The sun has a powerful effect upon the coloring matter, and so we readily "tan" on exposure to its rays. If the color gathers in spots, it forms freckles. [Footnote: This action of the sun on the pigment of the skin is very marked. Even among the Africans, the skin is observed to lose its intense black color in those who live for many months in the shades of the forest. It is said that Asiatic and African women confined within the walls of the harem, and thus secluded from the sun, are as fair as Europeans. Among the Jews who have settled in Northern Europe, are many of light complexion, while those who live in India are as dark as the Hindoos. Intense heat also increases this coloring matter, and thus a furnace-man's skin, even where protected by clothing, becomes completely bronzed. The black pigment has been known to disappear during severe illness, and a lighter color to be developed in its place. Among the negroes, are sometimes found people who have no complexion, _i. e._, there is no coloring matter in their skin, hair, or the iris of their eyes. These persons are called Albinos.]

II. HAIR AND NAILS.

The Hair and the Nails are modified forms of the cuticle.

FIG. 23.

THE HAIR is a protection from heat and cold, and shields the head from blows. It is found on nearly all parts of the body, except the palms of the hands and the soles of the feet. The outside of a hair is hard and compact, and consists of a layer of colorless scales, which overlie one another like the shingles of a house; the interior is porous, [Footnote: In order to examine a hair, it should be put on the slide of the microscope, and covered with a thin glass, while a few drops of alcohol are allowed to flow between the cover and the slide. This causes the air, which fills the hair and prevents our seeing its structure, to escape.] and probably conveys the liquids by which it is nourished.

Each hair grows from a tiny bulb (papilla), which is an elevation of the cutis at the bottom of a little hollow in the skin. From the surface of this bulb, the hair is produced, like the cuticle, by the constant formation of new cells at the bottom. When the hair is pulled out, this bulb, if uninjured, will produce a new one; but, when once destroyed, it will never grow again. [Footnote: Hair grows at the rate of about five to seven inches in a year. It is said to grow after death. This appearance is due to the fact that by the shrinking of the skin the part below the surface is caused to project, which is especially noticeable in the beard.] The hair has been known to whiten in a single night by fear, fright, or nervous excitement. When the color has once changed, it can not be restored. [Footnote: Hair dyes, or so-called "hair restorers," are almost invariably deleterious substances, depending for their coloring properties upon the action of lead or lunar caustic. Frequent instances of hair poisoning have occurred, owing to the common use of such dangerous articles. If the growth of the hair be impaired, the general constitution or the skin needs treatment. This is the work of a skillful physician, and not of a patent remedy. Dame Fashion has her repentant freaks as well as her ruinous follies, and it is a healthful sign that the era of universal hair dyeing has been blotted out from her present calendar, and the gray hairs of age are now honored with the highest place in "style" as well as in good sense and cleanliness.] (See p. 285.)

Wherever hair exists, tiny muscles are found, interlaced among the fibers of the skin. These, when contracting under the influence of cold or electricity, pucker up the skin, and cause the hair to stand on end. [Footnote: In horses and other animals which are able to shake the whole skin, this muscular tissue is much more fully developed than in man.] The hairs themselves are destitute of feeling. Nerves, however, are found in the hollows in which the hair is rooted, and so one feels pain when it is pulled. [Footnote: These nerves are especially abundant in the whiskers of the cat, which are used as feelers.] Thus the insensible hairs become wonderfully delicate instruments to convey an impression of even the slightest touch.

FIG. 24.

Next to the teeth and bones, the hair is the least destructible part of the body, and its color is often preserved for many years after the other portions have gone to decay. [Footnote: Fine downy hairs, such as are general upon the body, have been detected in the little fragments of skin found beneath the heads of the nails by which, centuries ago, certain robbers were fastened to the church doors, as a punishment for their sacrilege.]

THE NAILS protect the ends of the tender finger, and toe, and give us power more firmly to grasp and easily to pick up any object we may desire. They enable us to perform a hundred little, mechanical acts which else were impossible. At the same time, their delicate color and beautiful outline give a finish of ornament to that exquisite instrument, the hand. The nail is firmly set in a groove (matrix) in the cuticle, from which it grows at the root in length [Footnote: By making a little mark on the nail near the root we can see, week by week, how rapidly this process goes on, and so form some idea of what a multitude of cells must be transformed into the horny matter of the nail.] and from beneath in thickness. So long as the matrix at the root is uninjured, the nail will be replaced after any accident. (See p. 288.)

III. THE MUCOUS MEMBRANE.

STRUCTURE.--At the edges of the openings into the body, the skin seems to stop and give place to a tissue which is redder, more sensitive, more liable to bleed, and is moistened by a fluid, or mucus, as it is called. Really, however, the skin does not cease, but passes into a more delicate covering of the same general structure, viz., an outer, hard, bloodless, insensible layer, and an inner, soft, sanguine, nervous one. [Footnote: With a dull knife, we can scrape from the mucous membrane which lines the mouth some of the cuticle for examination under the microscope. In a similar way, we can obtain cuticle from the surface of the body for study and comparison.] Thus every part of the body is wrapped in a kind of double bag, made of tough skin on the outside, and tender mucous membrane on the inside.