Organs and Processes of Digestion : Part 8

Physiology and Hygiene for Secondary Schools
by Francis M. Walters

(Page 17 of 31)

Exercises. - 1. State the general purpose of digestion. How does digested food differ from that not digested?

2. Name all the divisions of the alimentary canal in the order in which the food passes through them.

3. What other work besides digestion is carried on by the alimentary canal?

4. What is gained by the mastication of the food? Why should mastication precede the other processes of digestion?

5. What is the work of the tongue in digestion?

6. State the purposes served by the gastric juice.

7. Give reasons for regarding the small intestine as the most important division of the food canal.

8. At what places, and by the action of what liquids, are fats, proteins, and starch digested?

9. What enzymes are found in the pancreatic juice? What is the digestive action of each?

10. Describe the work performed by the muscles of the stomach, the mouth, the esophagus, and the small intestine.

11. What advantages are derived from the use of cooked food?

12. State the advantages of drinking pure water.

13. If all the food that one needs to take at a single meal can be thoroughly masticated in fifteen minutes, why is it better to spend a longer time at the table?

14. What is meant by the overlapping of meals? What bad results follow? How avoided?

Practical Work

Examine a dissectible model of the human abdomen, noting the form, location, and connection of the different organs. Find the connection of the esophagus with the stomach, of the stomach with the small intestine, and of the small intestine with the large intestine. Sketch a general outline of the cavity, and locate in this outline its chief organs.

Where it is desirable to learn something of the actual structure of the digestive organs, the dissection of the abdomen of some small animal is necessary. On account of unpleasant features likely to be associated with such a dissection, however, this work is not recommended for immature pupils.

Dissection of the Abdomen. (Optional) - For individual study, or for a small class, a half-grown cat is perhaps the best available material. It should be killed with chloroform, and then stretched, back downward, on a board, the feet being secured to hold it in place.

The teacher should make a preliminary examination of the abdomen to see that it is in a fit condition for class study. If the bladder is unnaturally distended, its contents may be forced out by slight pressure. The following materials will be needed during the dissection, and should be kept near at hand: a sharp knife with a good point, a pair of heavy scissors, a vessel of water, some cotton or a damp sponge, and some fine cord. During the dissection the specimen should be kept as clean as possible, and any escaping blood should be mopped up with the cotton or the sponge. The dissection is best carried out by observing the following order:

1. Cut through the abdominal wall in the center of the triangular space where the ribs converge. From here cut a slit downward to the lower portion of the abdomen, and sideward as far as convenient. Tack the loosened abdominal walls to the board, and proceed to study the exposed parts. Observe the muscles in the abdominal walls, and the fold of the peritoneum which forms an apron-like covering over the intestines.

2. Observe the position of the stomach, liver, spleen, and intestines, and then, by pushing the intestines to one side, find the kidneys and the bladder.

3. Study the liver with reference to its location, size, shape, and color. On the under side, find the gall bladder, from which a small tube leads to the small intestine. Observe the portal vein as it passes into the liver. As the liver is filled with blood, neither it nor its connecting blood vessels should be cut at this time.

4. Trace out the continuity of the canal. Find the esophagus where it penetrates the diaphragm and joins the stomach. Find next the union of the stomach with the small intestine. Then, by carefully following the coils of the small intestine, discover its union with the large intestine.

5. Within the first coil of the small intestine, as it leaves the stomach, find the pancreas. Note its color, size, and branches. Find its connection with the small intestine.

6. Beginning at the cut portion of the abdominal wall, lift the thin lining of the peritoneum and carefully follow it toward the back and central portion of the abdomen. Observe whether it extends back of or in front of the kidneys, the aorta, and the inferior vena cava. Find where it leaves the wall as a double membrane, the mesentery, which surrounds and holds in place the large and small intestines. Sketch a coil of the intestine, showing the mesentery.

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