Which of the following is least associated with the adrenal medulla?

Correct Answer: D

Rationale: The correct answer is D because the adrenal medulla is primarily involved in the production of catecholamines, specifically epinephrine and norepinephrine, which are associated with the fight-or-flight response. This response is triggered by stress and prepares the body for action by increasing heart rate, dilating airways, and redirecting blood flow. On the other hand, the regulation of sugar, salt, and sex hormones is mainly controlled by the adrenal cortex, not the adrenal medulla. Therefore, while choices A, B, and C are directly related to the adrenal medulla's function, choice D is least associated with it.

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: C

Rationale: The correct answer is C: Thyroid. Iodine is essential for thyroid hormone production. A colloid is a gel-like substance found in the thyroid follicles. Goiter is a condition of thyroid enlargement. The other choices are incorrect because the pancreas (A) produces digestive enzymes and hormones like insulin, the parathyroid (B) regulates calcium levels, and the neurohypophysis (D) is part of the pituitary gland responsible for releasing hormones like vasopressin. Thus, the correct choice is the thyroid gland due to its association with iodine, colloid, and goiter.

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).