Which of the following cells in the stomach secrete pepsinogen?

Correct Answer: B

Rationale: The correct answer is B: chief cells. Chief cells are responsible for secreting pepsinogen in the stomach. Pepsinogen is an inactive form of pepsin, which is an enzyme that helps in protein digestion. Parietal cells secrete hydrochloric acid, not pepsinogen. Mucous neck cells secrete mucus to protect the stomach lining. Enteroendocrine cells secrete hormones like gastrin, but not pepsinogen. Therefore, the correct answer is B as chief cells are the specific cells that secrete pepsinogen in the stomach.

Correct Answer: C

Rationale: The correct answer is C: Digesting proteins. Pepsin is a digestive enzyme produced in the stomach that specifically breaks down proteins into smaller peptides. It works optimally in acidic environments, aiding in the digestion of proteins consumed in the diet. The other choices are incorrect because pepsin does not play a role in digesting carbohydrates (A), fats (B), or nucleic acids (D). Carbohydrates are primarily broken down by enzymes like amylase, fats by lipase, and nucleic acids by nucleases. Thus, pepsin's main function is to digest proteins in the stomach.

Correct Answer: B

Rationale: The correct answer is B: Hyperplasia of gastric mucosal lymphocytes. In a tumor producing large amounts of gastrin, hyperplasia of gastric epithelium (choice A) is expected due to increased gastrin stimulation. Excessive gastric acid secretion (choice C) is also expected as gastrin stimulates acid production. Histamine secretion in the gastric mucosa (choice D) can occur as histamine is released in response to gastrin. However, hyperplasia of gastric mucosal lymphocytes (choice B) is not a direct consequence of increased gastrin levels. Lymphocyte hyperplasia is more commonly associated with chronic inflammation or infection rather than gastrin overproduction.

Correct Answer: B

Rationale: Secretin is the correct answer because it is not a hormone that directly affects the stomach. Gastrin stimulates gastric acid secretion, GIP enhances insulin release, and neurotensin regulates gastric motility. Secretin primarily targets the pancreas and liver, stimulating the release of bicarbonate-rich pancreatic juice. This hormone does not have a direct major effect on the stomach like the other options. Therefore, Secretin is the exception among the listed GIT hormones affecting the stomach.

Correct Answer: C

Rationale: Rationale: 1. Gastric phase starts when food enters the stomach. 2. Chemoreceptors detect bolus composition to initiate gastric secretions. 3. This detection triggers release of gastric juices for digestion. 4. Neural stimulation also occurs during gastric phase, but not exclusively. 5. Contractility increases during gastric phase for mixing and churning. In summary, choice C is correct as chemoreceptors detect bolus composition during the gastric phase, while the other choices are incorrect because they do not accurately reflect the physiological processes during this phase.