The secretion of the bile comes from the liver and the pancreatic juice from the pancreas or sweetbreads, and both are poured into the intestines near the same point, so that they act together. The ferments they contain act in the following ways: They change starch into sugar, fat into fatty compounds, they curdle milk, and convert protein compounds into soluble peptones.
The process of digestion is finally ended in the intestines, where absorption into the system takes place. There is no opening at all from the bowels into the body, but the digestive nutriment is picked up by the blood when handed into the body from the intestines by means of countless little cells called villi, that line the walls of the intestines. These villi cells have little hair-like projections extending into the intestines, which constantly move; these protrusions, as they move about, catch on to the digested nutriment, draw it into the cells themselves, where it is handed on to the blood, when it is later on distributed to all parts of the body. You can realize that an immense number of these absorption cells are present when the length of the intestine is considered. In the ox the intestine is nearly 200 feet long. After the nutriment is drawn from the food the undigested portions are voided periodically as feces or dung.
The four main divisions of the ruminant’s stomach are pictured here. The first three divisions are the store-houses for food until it is fully prepared for the fourth stomach or abomasum.]
=Absorption of the Nutriment.=--Digestion, therefore, is a dissolving process; food is admitted to the system by means of cells. You remember that all plant food first passes into a soluble state before it can enter the roots and be conveyed to the parts of the plants that require additional food for growth. In the case of plants the entrance is by means of the root hairs. In the case of the animal, entrance in the body is by means of the villi cells that line the intestines. From this we see that digestion is both an intricate and delicate process. Any loss of appetite, any disturbance of the digestion work, and any irregularity of the bowels bear decided results, one way or the other, to the rest of the system; and any disturbance of the body at other points, although having no direct relation to the digestion system, sooner or later affects the digestion and in so doing causes additional trouble.