The stomach produces acids, which denature protein, and popsin that digests protein. The cell membranes of the epithelial cells lining the stomach contain protein. The protein in the epithelial cells are not denatured or digested because

Correct Answer: B

Rationale: The correct answer is B: mucus coats the epithelium. The mucus layer acts as a protective barrier that prevents the acid and pepsin from coming into direct contact with the epithelial cells. This physical barrier helps to shield the cell membranes from denaturation and digestion. Choice A is incorrect because the type of protein in the cell membranes does not determine their resistance to denaturation and digestion. Choice C is incorrect because cell membranes are not destroyed, and mitotic activity does not play a role in protecting the cell membranes. Choice D is incorrect because hormones do not directly protect the cell membranes from acid and pepsin; rather, it is the mucus layer that provides the necessary protection.

Correct Answer: A

Rationale: The correct answer is A: appendicitis. Sudden abdominal pain, fever, loss of appetite, and nausea are classic symptoms of appendicitis. The pain often starts near the belly button and migrates to the lower right abdomen, where the appendix is located. Appendicitis is a medical emergency that requires immediate attention to prevent complications like a burst appendix. Heartburn (B) typically presents with a burning sensation in the chest, and diarrhea (C) presents with loose, watery stools. Hemorrhoids (D) are swollen blood vessels in the rectum that cause discomfort but do not typically present with the symptoms described.

Correct Answer: D

Rationale: The correct answer is D because pepsinogen and gastric lipase are indeed two enzymes secreted into the lumen of the stomach. Pepsinogen is converted to pepsin, an enzyme that breaks down proteins, while gastric lipase helps in the digestion of fats. A is incorrect because carbonic anhydrase is not a hormone but an enzyme involved in acid secretion. B is incorrect because Peyer's patches are actually found in the small intestine, not the stomach, and they are involved in the immune system. C is incorrect because the vagus nerve stimulates, rather than inhibits, acid secretion in response to a meal. In summary, D is correct as it accurately describes enzymes secreted in the stomach, while the other choices contain factual inaccuracies about stomach function.

Correct Answer: A

Rationale: The correct answer is A because pancreatic juice contains Trypsin for protein digestion, Amylopsin for carbohydrate digestion, and Steapsin for fat digestion. Trypsin breaks down proteins into peptides, Amylopsin breaks down carbohydrates into sugars, and Steapsin breaks down fats into fatty acids and glycerol. Pepsin, Rennin, and Gastric Lipase (option B) are enzymes found in the stomach, while Erepsin, Invertase, and Lipase (option C) are enzymes found in the small intestine. Ptyalin, Maltase, and Lactase (option D) are enzymes involved in digestion but are not found in pancreatic juice.

Correct Answer: C

Rationale: The correct answer is C: acetylcholine. Acetylcholine is involved in regulating secretory cells in the gastric mucosa by stimulating the release of gastric acid and enzymes. Norepinephrine and dopamine are not directly involved in gastric secretions. Insulin is a hormone involved in glucose metabolism, not gastric regulation. Acetylcholine's role in stimulating gastric secretions makes it the correct choice.