The Muscular System : Part 4

Physiology and Hygiene for Secondary Schools
by Francis M. Walters

(Page 18 of 27)

The increase in the flow of the blood and the lymph causes changes to take place more rapidly in the liquids around the cells, thereby increasing the supply of food and oxygen, and hastening the removal of waste.

One should plan for Exercise. - Since exercise is demanded by the nature and plan of the body, to neglect it is a serious matter. People do not purposely omit exercise, but from lack of time or from its interference with the daily routine of duties, the needed amount is frequently not taken. Especially is this true of students and others who follow sedentary occupations. People of this class should plan for exercise as they plan for the other great needs of the body - food, sleep, clothing, etc. It is only by making a sufficient amount of muscular work or play a regular part of the daily program that the needs of the body for exercise are adequately supplied.

Amount and Kind of Exercise. - The amount of exercise required varies greatly with different individuals, and definite recommendations cannot be made. For each individual also the amount should vary with the physical condition and the other demands made upon the energy. One in health should exercise sufficiently to keep the muscles firm to the touch and the body in a vigorous condition.

Of the many forms of exercise from which one may choose, the question is again one of individual adaptability and convenience. While the different forms of exercise vary in their effects and may be made to serve different purposes, the consideration of these is beyond the scope of an elementary text. As a rule one will not go far wrong by following his inclinations, observing of course the conditions under which exercise is taken to the best advantage.

General Rules for Healthful Exercise. - That exercise may secure the best results from the standpoint of health, a number of conditions should be observed: 1. It should not be excessive or carried to the point of exhaustion. Severe physical exercise is destructive to both muscular and nervous tissues. 2. It should, if possible, be of an interesting nature and taken in the open air. 3. It should be counter-active, that is, calling into play those parts of the body that have not been used during the regular work. 4. It should be directed toward the weak rather than toward the strong parts of the body. 5. When one is already tired from study, or other work, it should be taken with moderation or omitted for the time being.

Massage. - In lieu of exercise taken in the usual way, similar effects are sometimes obtained by a systematic rubbing, pressing, stroking, or kneading of the skin and the muscles by one trained in the art. This process, known as massage, may be gentle or vigorous and is subject to a variety of modifications. Massage is applied when one is unable to take exercise, on account of disease or accident, and also in the treatment of certain bodily disorders. A weak ankle, wrist, or other part of the body, or even a bruise, may be greatly benefited by massage. The flow of blood and lymph is stimulated, causing new materials to be passed to the affected parts and waste materials to be removed. Massage, however, should never be applied to a boil, or other infected sore. The effect in this case would be to spread the infection and increase the trouble.

Summary. - Motion is provided for in the body mainly through the muscle cells. These are grouped into working parts, called muscles, which in turn are attached to the movable parts of the body. The striated muscles, as a rule, are attached to the mechanical devices found in the skeleton, and bring about the voluntary, movements. The non-striated muscles surround the parts on which they act, and produce involuntary movements. Both, however, are under the control of the nervous system. To bring about the opposing movements of the body, the striated muscles are arranged in pairs; and to increase their motion, the bones are used as levers. Physical exercise is necessary both for the development of the muscles and for the health and vigor of the entire body.

Exercises. - 1. Compare the striated and non-striated muscles with reference to structure, location, and method of work.

2. In what respects is the muscular tissue of the heart like the striated, and in what respects like the non-striated, muscular tissue?

3. If muscles could push as well as pull, would so many be needed in the body? Why?

4. Locate muscles that work to some extent against elasticity and gravity.

5. Locate five muscles that act as flexors; five that act as extensors; two that act as adductors; and two as abductors. Locate sphincter and radiating muscles.

6. By what means does the nervous system control the muscles?

7. Give proofs of the change of potential into kinetic energy during muscular contraction.

8. Define the essential properties of muscular tissue and state the purpose served by each.

9. Describe a lever. For what general purpose are levers used in the body? What other purpose do they serve outside of the body?

10. Why are levers of the second class not adapted to the work of the body?

11. Name the class of lever used in bending the elbow; in straightening the elbow; in raising the knee; in elevating the toes; and in biting. Why is one able to bite harder with the back teeth than with the front ones when the same muscles are used in both cases?

12. Measure the distance from the middle of the palm of the hand to the center of the elbow joint. Find the attachment of the tendon of the biceps muscle to the radius and measure its distance to the center of the elbow joint. From these distances calculate the force with which the biceps contracts in order to support a weight of ten pounds on the palm of the hand.

13. How does exercise benefit the health? How does a short walk "clear the brain" and enable one to study to better advantage?

14. When exercisers taken for its effects upon the health, what conditions should be observed?

D.C. Heath and Co. - Publishers
Original copyright 1909