Wednesday, December 15, 2010
1:02 AM | Posted by Shams Burki | Edit Post
A. Bicarbonate transport
B. Epithelial regenerative capacity
C. Mucosal blood flow
D. Mucus secretion
E. Pepsin production
The correct answer is E. Pepsin production is a normal physiologic activity of the stomach that, in conditions of stress, may overwhelm the stomach's weakened defenses and result in gastric ulceration. Gastric acid production is another condition that may increase and cause gastric ulceration. Furthermore, these two factors may remain unchanged and still result in gastric ulcers if the gastric defenses are weakened by stress.
All of the other choices represent normal defensive forces in the stomach. Increased bicarbonate transport (choice A) would protect the gastric epithelium from the potentially harmful acidity of the gastric contents. The adherent mucus is relatively alkaline, providing local protection to the superficial mucosa.
Gastric epithelial cells can normally replicate rapidly, allowing mucosal defects to be rapidly repaired. Increasing the regenerative capacity of the epithelium (choice B) would have a protective effect against ulceration.
The gastric mucosa is richly supplied with blood, providing the epithelial cells with an ample supply of nutrients, oxygen, and bicarbonate to contend with the harsh gastric microenvironment. Stress ulcers are associated with compromised gastric blood flow, not increased flow (choice C).
Mucus protects the gastric epithelium by virtue of being water insoluble, impermeable to pepsin, and slowly permeated by acid (H+). Increasing mucus production (choice D) has a protective effect for the gastric mucosa.