Gastrin secretion is stimulated by all but:

Correct Answer: C

Rationale: Rationale: Gastrin secretion is primarily stimulated by luminal peptides and vagal discharge, which promote gastric acid secretion. Luminal acid, on the other hand, inhibits gastrin release as it acts as a negative feedback mechanism to regulate acid production. Phenylalanine does not directly stimulate gastrin secretion. Therefore, the correct answer is C as luminal acid inhibits, not stimulates, gastrin release. The other choices are incorrect because luminal peptides and vagal discharge are known stimulants of gastrin secretion, while phenylalanine does not have a direct effect on gastrin release.

Correct Answer: A

Rationale: Step 1: NAD+ is a reactant in the citric acid cycle, not a product. Step 2: NAD+ is reduced to NADH during the cycle. Step 3: NAD+ is not directly produced as a final product in the cycle. Step 4: Therefore, A: NAD+ is NOT produced by the citric acid cycle. Summary: B: CO2 and D: FADH2 are produced in the cycle, while C: GTP is generated through substrate-level phosphorylation.

Correct Answer: D

Rationale: The correct answer is D: Adrenal. The adrenal glands are located just superior to the kidneys. They are responsible for producing hormones such as cortisol, adrenaline, and aldosterone. The other choices are incorrect because the pituitary gland is located in the brain, the pancreas is located in the abdominal cavity, and the ovaries are located in the pelvic region. The adrenal glands are the only glands located just superior to the kidneys, making choice D the correct answer.

Correct Answer: B

Rationale: The correct answer is B: nerve axons. The hypothalamus communicates with the posterior pituitary lobe through nerve axons that form the hypothalamic-pituitary tract. This pathway allows for the release of hormones such as oxytocin and vasopressin directly into the bloodstream. Blood vessels (choice A) are not directly responsible for the connection between the hypothalamus and the posterior pituitary. Cartilage (choice C) and bone (choice D) do not play a role in this connection and are not anatomically linked to the hypothalamus and posterior pituitary.

Correct Answer: D

Rationale: The correct answer is D: Throat to stomach. The esophagus connects the throat (pharynx) to the stomach, allowing food to pass from the mouth to the stomach for digestion. Choice A is incorrect as the esophagus does not connect the throat to the lungs. Choices B and C are also incorrect as they mention connections that do not involve the esophagus. The esophagus specifically functions to transport food and liquids from the mouth to the stomach for further digestion.