PTH activates vitamin D, which aids in the absorption of:

Correct Answer: A

Rationale: The correct answer is A: calcium. PTH (parathyroid hormone) activates vitamin D, which in turn helps in the absorption of calcium in the intestines. This is crucial for maintaining bone health and normal calcium levels in the blood. Vitamin C (Choice B) is not directly related to PTH or vitamin D in calcium absorption. Iron (Choice C) absorption is influenced by factors other than PTH and vitamin D. Phosphate (Choice D) absorption is primarily regulated by fibroblast growth factor 23 and not by PTH or vitamin D. Thus, the correct answer is A as it directly corresponds to the role of PTH and vitamin D in calcium absorption.

Correct Answer: C

Rationale: The correct answer is C because ACTH (adrenocorticotropic hormone) stimulates the adrenal cortex to secrete cortisol. Step 1: ACTH is released from the anterior pituitary gland. Step 2: ACTH stimulates the adrenal cortex to produce and release cortisol. Choice A is incorrect because CRH is secreted by the hypothalamus to stimulate ACTH release. Choice B is incorrect because cortisol is produced in the adrenal cortex, not the adenohypophysis. Choice D is incorrect because the adrenal medulla secretes adrenaline and noradrenaline, not glucagon.

Correct Answer: C

Rationale: Rationale: Bronzing is a characteristic symptom of chronic adrenal cortical insufficiency (Addison's disease) due to increased production of melanin. In this condition, the adrenal glands do not produce enough steroid hormones, leading to skin hyperpigmentation. This differs from hyperglycemia (choice A), Cushing syndrome (choice B), and ADH insufficiency (choice D), which do not directly cause bronzing. Therefore, the correct choice is C.

Correct Answer: B

Rationale: The correct answer is B because the adrenal medulla secretes epinephrine and norepinephrine, which are hormones involved in the body's response to stress or danger. These hormones help increase heart rate, blood pressure, and energy levels. Choices A, C, and D are incorrect because: A: The adrenal medulla is actually part of the sympathetic division of the autonomic nervous system, which is responsible for the "fight-or-flight" response, not the "feed-and-breed" division. C: Steroids are produced by the adrenal cortex, not the adrenal medulla. D: Cushing syndrome is caused by overactivity of the adrenal cortex, not the adrenal medulla.

Correct Answer: B

Rationale: Hyperglycemia leads to glucosuria and polyuria because when blood glucose levels are high, the kidneys cannot reabsorb all the glucose, leading to glucose spilling into the urine (glucosuria) and drawing more water into the urine, resulting in increased urine production (polyuria). This process helps to lower blood glucose levels. Other options are incorrect as hyperglycemia is not caused by excess insulin (A), does not cause hypocalcemia and hyperphosphatemia (C), and is not characteristic of adrenal insufficiency (D).