Question

explain why a powerful enzyme like pepsin is typically not able to digest the mucus and then the wall of the stomach.

The small intestine lacks the thick mucous layer found in the stomach. Why do you think pepsin doesn't typically attack the small intestine?

People sometimes develop ulcers, or holes, in the lining of the first part of the small intestine. What might cause these ulcers to form?

Answer 1

1. The epithelial cell lining of the stomach protect the stomach wall by producing and secreting a bicarbonate-rich solution to form a coating over the mucosa layer of stomach.

2.  In the intestine the gastric acids are neutralized (pH 7), by the bile secereted by liver and thus  pepsin is no longer effective.

3. The most common cause of ulcers is infection of the stomach by bacteria called Helicobacter pylori (H pylori). Since the first part of small intestine is directly attached with stomach the infection some times extends up to the initial part of intestine.