Glands and the Work of Excretion : Part 4

Physiology and Hygiene for Secondary Schools
by Francis M. Walters

(Page 16 of 26)

Misunderstood Symptoms. - Pains in the small of the back, an increase in the secretions of the kidneys, and a sediment in the urine very naturally suggest some disorder of the kidneys. It is a fact, however, that these symptoms have little or no relation to the state of the kidneys and may occur when the kidneys are in a perfectly healthy condition. The kidneys are not located in the small of the back, but above this place, so that pains in this region are evidently not from the kidneys, while the increase in the flow of the urine may arise from a number of causes, one of which is an increase of certain waste products passed into the blood. The symptoms referred to are frequently the results of nervous exhaustion, resulting from over study, worry, eye strain, or some other condition that overtaxes the nervous system. When this is the case, relief is obtained through resting the nerves. Actual disease of the kidneys can only be determined through a chemical and microscopic examination of the urine. To resort to some patent medicine for kidney trouble without knowing that such trouble exists, as is sometimes done, is both foolish and unhygienic.

Alcoholic Beverages and the Elimination of Waste. - Causing as it does such serious diseases as cirrhosis of the liver and Bright's disease of the kidneys, alcohol will greatly interfere in this way with the elimination of waste. There is also evidence to the effect that it interferes with waste elimination before the stage is reached of causing disease of these organs. Researches have shown that alcohol increases the amount of uric acid in the body and decreases the amount of urea found in the urine. The conclusion to be drawn is that alcohol interferes in some way with the change of the harmful uric acid into the comparatively harmless urea - an interference which in some instances results in great harm. It has also been shown that malted liquors, such as beer and ale, contain substances which, like the caffeine of tea and coffee, are readily converted into uric acid. Wines contain acids which may also act injuriously. The harm which such substances do is, of course, additional to that caused by the alcohol.

Summary. - As a result of the oxidations and other changes at the cells, substances are produced that can no longer serve a purpose in the body. They are of the nature of waste, and their continuous removal from the body is as necessary to the maintenance of life as the introduction of food and oxygen. The organs whose work it is to remove the waste, excepting the lungs, are glands; and the material which they remove are of the nature of secretions. From the cells, the waste passes through the lymph in the blood. From the blood it is separated by the excretory organs and passed to the exterior of the body.

Exercises. - 1. What general purposes are served by the glands in the body?

2. What are the parts common to all glands? What purpose is served by each of these parts?

3. How do tubular glands differ in structure from saccular glands? What is a racemose gland? Why so called?

4. Describe the nature of the secretory process.

5. What conditions render necessary the formation of waste materials in the body? Why must these be removed?

6. How do the waste materials get from the cells to the organs of excretion?

7. Show by a drawing the connections of the kidneys with the large blood vessels and the bladder. Name parts of drawing.

8. In what do the uriniferous tubes have their beginning? In what do they terminate? With what are they lined?

9. Why should the blood pass through two sets of capillaries in the kidneys?

10. Bright's disease of the kidneys affects the uriniferous tubes and interferes with their work. What impurity is then left in the blood?

11. Trace water and salts from the Malpighian capsules to the bladder, naming parts through which they pass.

12. Trace carbon dioxide from the cells to the outside atmosphere.

13. How does the quantity of material introduced into the body compare with that which is removed by the organs of excretion?

14. Name two ways of lessening the work of the kidneys.

15. Why is the drinking of plenty of pure water a healthful practice?

Practical Work

To suggest the Double Work of Glands. - Prepare a simple filter by fitting a piece of porous paper into a glass funnel. Through this pass pure water and also water having salt dissolved in it and containing some sediment, as sand. The water and the dissolved salt pass through, while the sediment remains on the filter. Now substitute a fresh piece of paper in the funnel and drop on its surface a little solid coloring matter, such as cochineal. Again pass the liquid through the funnel. This time it comes through colored, the color being added by the filter. Compare the filter and materials filtered to the gland and the materials concerned in secretion (blood, the liquid secreted, substances added by the gland, etc.).

Summary of Part I

The body is an organization of different kinds of cells; it grows through the growth and reproduction of these cells; and its life as a whole is maintained by providing such conditions as will enable the cells to keep alive. Of chief importance in the work of the body is a nutrient fluid which supplies the cells with food and oxygen and relieves them of waste. A moving portion of this fluid, called the blood, serves as a transporting agent, while another portion, called the lymph, passes the materials between the blood and the cells. Through their effects upon the blood and the lymph, the organs of circulation, respiration, digestion, and excretion minister in different ways to the cells, and aid in the maintenance of life. By their combined action two distinct movements are kept up in the body, as follows:

1. An inward movement which carries materials from the outside of the body toward the cells.

2. An outward movement which carries materials from the cells to the outside of the body.

Passing inward are the oxygen and food materials in a condition to unite with each other and thereby change their potential into kinetic energy. Passing outward are the oxygen and the elements that formed the food materials after having united at the cells and liberated their energy.

As a final and all-important result, there is kept up a continuous series of chemical changes in the cells. These liberate the energy, provide special substances needed by the cells, and preserve the life of the body.

In the chapters which follow, we are to consider the problem of adjusting the body to and of bringing it into proper relations with its surroundings.

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