What is the most likely effect of a deficiency of aldosterone?

Correct Answer: C

Rationale: Rationale: 1. Aldosterone regulates sodium and water balance in the body. 2. Deficiency leads to decreased sodium reabsorption, causing low blood volume. 3. Low blood volume results in hypotension due to reduced blood flow to tissues. 4. Choices A and B are incorrect as aldosterone deficiency does not cause high blood pressure or low potassium levels. 5. Choice D is incorrect as goiter formation is mainly related to thyroid hormone imbalance, not aldosterone deficiency.

Correct Answer: D

Rationale: Elevated plasma cortisol levels suppress the secretion of ACTH through negative feedback. High cortisol levels signal the hypothalamus and pituitary to decrease the release of CRH and ACTH, respectively, to maintain homeostasis. This is a regulatory mechanism to prevent excessive cortisol production. A: Elevated blood glucose levels do not directly suppress ACTH secretion. B: Dietary iodine is not related to ACTH secretion. C: CRH stimulates ACTH release, so it does not suppress its secretion.

Correct Answer: A

Rationale: Step-by-step rationale for why choice A is correct: 1. The adrenal cortex is indeed the target gland of ACTH (Adrenocorticotropic hormone). 2. ACTH stimulates the adrenal cortex to produce and release corticosteroid hormones. 3. These corticosteroid hormones play crucial roles in regulating metabolism, immune response, and stress response. 4. Therefore, choice A accurately describes the relationship between the adrenal cortex and ACTH. Summary: Choice A is correct because the adrenal cortex is the target gland of ACTH, not the other choices. The adrenal medulla secretes catecholamines (choice B), hormones that raise blood glucose (not lower, as in choice C), and iodine-containing hormones are secreted by the thyroid gland, not the adrenal cortex (choice D).

Correct Answer: D

Rationale: The correct answer is D because both Cushing syndrome and Addison's disease are disorders of the adrenal cortex. Cushing syndrome involves excessive cortisol production, while Addison's disease is characterized by insufficient cortisol production. Both conditions directly affect the adrenal cortex, leading to hormonal imbalances. Choice A is incorrect because Cushing syndrome involves hyperfunction, not hypofunction. Choice B is incorrect as it states hypersecretion, which is true for Cushing syndrome but not for Addison's disease. Choice C is incorrect because while replacement cortisol therapy is used for Addison's disease, it is not the only treatment option, and it does not apply to Cushing syndrome.

Correct Answer: C

Rationale: The correct answer is C because epinephrine stimulates the hepatic conversion of glycogen into glucose. This process, called glycogenolysis, releases stored glucose from the liver into the bloodstream, increasing blood glucose levels. Choice A is incorrect because epinephrine does not directly increase glucose transport into cells. Choice B is incorrect as gluconeogenesis is the synthesis of new glucose, not the release of stored glucose. Choice D is incorrect because fatty acids are not directly converted into glucose by epinephrine.