Energy Supply of the Body : Part 3

Physiology and Hygiene for Secondary Schools
by Francis M. Walters

(Page 14 of 25)

The Problem of Increasing One's Energy. - Since the energy supply is kept up through the food and the oxygen, it might be inferred that the introduction of these substances into the body in larger amounts would increase the energy at one's disposal. This does not necessarily follow. Oxidation at the cells is preceded by digestion, absorption, circulation, and assimilation. It is followed and influenced by the removal of wastes from the body.

A careful study of the problem leads to the conclusion that while the energy supply to the body does depend upon the introduction of the proper amounts of food and oxygen, it also depends upon the efficiency of the vital processes. The maximum amount of energy may, therefore, be expected when the body is in a condition of perfect health. Hence, one desiring to increase the amount of his energy must give attention to all those conditions that improve the health.

Effect of Stimulants on the Energy Supply. - In the effort to get out of the body as much as possible of work or of pleasure, various stimulants, such as alcohol, tobacco, and strong tea and coffee, have been used. Though these have the effect of giving a temporary feeling of strength and of enabling the individual in some instances to accomplish results which he could not otherwise have brought about, the general effect of their use is to lessen, rather than to increase, the sum total of bodily power. The student, for example, who drinks strong coffee in order to study late at night is able to command less energy on the day following. While enabling him to draw upon his reserve of nervous power for the time being, the coffee deprives him of sleep and needed rest.

The danger of stimulants, so far as energy is concerned, is this: they tend to exhaust the bodily reserve so that there is not sufficient left for properly running the vital processes. Evidences of their weakening effect are found in the feeling of discomfort and lassitude which result when stimulants to which the body has become accustomed are withdrawn. Not until one gets back his bodily reserve is he able to work normally and effectively. Increase in bodily energy comes through health and not through the use of stimulants.

Summary. - The body requires a continuous supply of energy. To obtain this supply, materials possessing potential, or stored-up, energy are introduced into it. The free oxygen of the air and the substances known as foods, on account of the chemical relations which they sustain to each other, contain potential energy and are utilized for supplying the body. So long as the foods are not oxidized, the energy remains in the potential form, but in the process of oxidation the potential energy is changed to kinetic energy and made to do the work of the body.

Exercises. - 1. In what different ways does the body use energy?

2. Show that a stone lying against the earth has no energy, while the same stone above the earth has energy.

3. How does potential energy differ from kinetic energy?

4. What kind of energy is possessed by a bent bow? By a revolving wheel? By a coiled spring? By the wind? By gunpowder?

5. How does decomposing water with electricity store energy?

6. Account for the energy possessed by the oxygen of the air and food substances.

7. Trace the energy supply of the body back to the sun.

8. Why must both oxygen and food be introduced into the body in order to supply it with energy?

9. How may overwork and over exercise diminish the energy supply of the body?

10. How may one increase the amount of his energy?

Practical Work

Suggested Experiments. - 1. The change of kinetic into potential energy may be shown by stretching a piece of rubber, by lifting a weight, and by separating the armature from a magnet.

2. The change of potential into kinetic energy may be shown by letting weights fall to the ground, by releasing the end of a piece of stretched rubber, and by burning substances.

3. The change of one form of kinetic energy to another may be illustrated by rubbing together two pieces of wood until they are heated, by ringing a bell, and by causing motion in air or in water by heating them. If suitable apparatus is at hand, the transformation of electrical energy into heat, light, sound, and mechanical motion can easily be shown.

4. A weight connected by a cord with some small machine and made to run it, will help the pupil to grasp the general principles in the storage of energy through gravity. A vessel of water on a high support from which the water is siphoned on to a small water wheel will serve the same purpose.

5. The storing of energy by chemical means may be illustrated by decomposing potassium chlorate with heat or by decomposing water by means of a current of electricity.

6. Study the transfer of energy from the body to surrounding objects, as in moving substances and lifting weights.

Fill a half gallon jar two thirds full of water and carefully take the temperature with a chemical thermometer. Hold the hand in the water for four or five minutes and take the temperature again. Inference.

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