Complete the following sentence: Lipid-soluble hormones are…

Correct Answer: C

Rationale: The correct answer is C because lipid-soluble hormones can freely diffuse through cell membranes to interact with intracellular receptors, leading to changes in gene expression. This mechanism is characteristic of lipid-soluble hormones, such as steroid hormones. Choice A is incorrect because lipid-soluble hormones are not constantly produced in the anterior pituitary gland. Choice B is incorrect as lipid-soluble hormones are hydrophobic, not hydrophilic, and are often transported bound to carrier proteins in the blood. Choice D is incorrect because lipid-soluble hormones are not formed from amino acids; rather, they are derived from cholesterol or similar compounds.

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: The correct answer is A because gastrin primarily stimulates gastric acid secretion and gastric motility, not insulin secretion. Gastrin is released in response to the presence of food in the stomach, leading to increased gastric acid production and motility to aid in digestion. Insulin secretion is mainly regulated by glucose levels in the blood and hormones like insulin and glucagon. Therefore, the stimulation of insulin secretion after a carbohydrate meal is not a direct action of gastrin. Choices B, C, and D are incorrect because they accurately describe the actions of gastrin in the digestive system.

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.