Which cells secrete hydrochloric acid in the stomach?

Correct Answer: A

Rationale: The correct answer is A: Parietal cells. Parietal cells secrete hydrochloric acid in the stomach to create the acidic environment necessary for digestion. They also secrete intrinsic factor for vitamin B12 absorption. Chief cells produce pepsinogen, not hydrochloric acid. Mucous neck cells secrete mucus to protect the stomach lining. Enteroendocrine cells secrete hormones like gastrin, not hydrochloric acid. Therefore, the correct choice is A as it directly produces hydrochloric acid in the stomach.

Correct Answer: C

Rationale: The correct answer is C: Lactase. Lactase is an enzyme produced in the small intestine, not in the pancreas. The exocrine pancreas secretes digestive enzymes like chymotrypsinogen, proelastase, and lipase to aid in the digestion of proteins, fats, and carbohydrates. Lactase is responsible for breaking down lactose, a sugar found in dairy products, and is produced in the small intestine. Therefore, C is the correct answer. Choices A, B, and D are incorrect because chymotrypsinogen, proelastase, and alph are all enzymes produced by the pancreas to aid in digestion.

Correct Answer: D

Rationale: The correct answer is D because G cells in the gastric pit secrete gastrin, not histamine. Gastrin stimulates the release of hydrochloric acid in the stomach. Mucous cells are not enteroendocrine, so A is incorrect. G cells are not exocrine, making B incorrect. D cells secrete somatostatin, not histamine, so C is also incorrect.

Correct Answer: C

Rationale: The correct answer is C because carcinoid syndrome can occur with carcinoid tumors of the appendix and ileum. Carcinoid tumors of the appendix can lead to carcinoid syndrome due to the release of serotonin and other vasoactive substances. Similarly, carcinoid tumors localized to the ileum can also produce these substances, leading to the development of carcinoid syndrome. Choices A and B alone are not comprehensive enough as both sites can give rise to carcinoid syndrome. Choice D is incorrect as carcinoid syndrome can indeed occur with tumors from both sites.

Correct Answer: A

Rationale: The correct answer is A. Mass peristalsis refers to the coordinated contraction of the smooth muscle in the colon that helps move fecal matter towards the rectum. This process specifically occurs in the large intestine, not the small intestine. Therefore, choice A is incorrect. Choice B is incorrect because mass peristalsis is actually a rapid and powerful movement, not slow. Choice C is correct as it accurately describes the role of mass peristalsis in facilitating the movement of fecal matter in the large intestine. Choice D is incorrect because choice A is incorrect.