Caused when normal protective mechanisms break down i. The epithelium is then damaged as pepsin and other materials begin to break down the stomach wall ii. When this becomes severe, a bleeding ulcer develops 5. The pancreas also secretes a lot of alkaline materials, which deactivate the acids of the stomach as the food passes into the small intestine 6. Once food has been released to this organ, it is broken down, but nutrients have yet to be absorbed b.
Epithelial cells secrete a thin, watery mucus e.
As a result, the lining of the large intestine is very smooth b. The most noticeable thing about vertebrate digestive systems is that herbivores have fairly long digestive systems 1. This is illustrated on p. 441 with a drawing of a coyote and koala intestine B. Herbivores are highly specialized, since plant cell walls contain cellulose 1. They often have special chambers in the gut that house microbes a. These microbes assist in breaking down cellulose 2.