Personal hygiene and physical training for women

by Anna M. Galbraith

Intestinal Digestion.—The chemical changes which food undergoes in the small and large intestines are exceedingly complex. Digestion in the intestine is due to the combined action of the bile, pancreatic juice, and succus entericus. The material which enters the duodenum from the stomach is known as the chyme. The acid chyme provokes a flow of bile and pancreatic juice. It acts upon the prosecretin in the duodenal mucous membrane in such a manner that secretin, a hormone, is formed and carried by the blood to the cells of the pancreas which it stimulates.

Bile is a secretion of the cells of the liver and from the inner wall of the gall-bladder; after elaboration, bile is stored up in part at least in the gall-bladder. The secretion of bile is irregular in quantity, as is the case with the gastric juice, and appears to be induced by chemical excitants, of which acids, especially hydrochloric, seems to be especially effective. Of the nutrients, the proteins exert the most influence. Less secretion follows the ingestion of carbohydrates than of proteins.

Formerly it was supposed that fatty foods checked the secretion of bile, but later experiments have proved that, to the contrary, they increase its secretion; and olive oil is a powerful cholagogue.

Bile precipitates the proteins of the chyme, neutralizes the acidity of the gastric juice, dissolving the fatty acids, and activates the lipase or steapsin of the pancreatic juice and assists in the absorption of fats. When for any reason the discharge of bile is retarded and the organism attempts to eliminate it through the kidneys, the tissues become charged with its compounds and take on a yellowish coloration.

Pancreatic Juice.—The second action upon the food in the intestine is that of the bicarbonate of soda contained in the pancreatic and intestinal juices, which neutralizes its acidity; and pancreatic digestion can only take place in an alkaline medium.

The pancreatic juice has the most comprehensive action of all of the digestive fluids; it contains a great variety of enzymes and acts upon all classes of nutrients. Its flow is intermittent, being induced by the action of the acids in the partially digested food from the stomach.

The pancreatic secretion attains its maximum pressure about three hours after a meal, but this varies according to the character of the meal. The enzymes of the pancreatic fluid are trypsin, amylopsin, lipase or steapsin, and pancreatic rennin.

Trypsin.—Pancreatic juice alone has but little influence on proteins, but when mixed with succus entericus its influence is great. Trypsin differs from pepsin by acting in an alkaline or neutral solution, and a free mineral acid, like hydrochloric, stops its operations; it acts much more powerfully and rapidly than pepsin. In conjunction with other enzymes it splits protein foods into simpler compounds, which may be regarded as the building stones of the original proteins.

Amylopsin.—The digestion of starch in the intestine is mainly effected by means of a diastatic ferment or enzyme in the pancreatic juice, called “amylopsin.” This enzyme has the power of hydrolyzing the starch mostly into maltose.

Steapsin or Lipase.—The pancreatic secretion acts vigorously on fats, not only splitting them into fatty acids and glycerin, but, in conjunction with the bile, also effects their emulsification. This latter result is doubtless aided by the soaps which form a union of the fatty acids and alkaline bases (mostly sodium) in the bile. The cleavage of the fats is due to the enzyme steapsin.