Which of the following is a function of parathyroid hormone?

Correct Answer: D

Rationale: The correct answer is D: It increases plasma levels of calcium. Parathyroid hormone (PTH) acts to increase calcium levels in the blood by stimulating the release of calcium from bones, enhancing calcium absorption in the intestines, and reducing calcium excretion in the kidneys. This process helps maintain proper calcium levels in the blood. Choices A, B, and C are incorrect because PTH does not cause the excretion of calcium in the urine (A), stimulate osteoblastic activity to form bone (B), or stimulate the thyroid gland to secrete calcitonin (C).

Correct Answer: A

Rationale: The correct answer is A: Lowers blood glucose levels. Insulin is a hormone produced by the pancreas that helps regulate blood glucose levels by promoting the uptake of glucose into cells for energy storage. This process reduces the concentration of glucose in the bloodstream. Choices B, C, and D are incorrect because insulin does not stimulate cells to make glucose (B), deficiency does not cause diabetes insipidus (C), and it does not directly affect blood volume (D).

Correct Answer: A

Rationale: The correct answer is A: excess facial hair. Virilization refers to the development of male secondary sexual characteristics in females due to increased androgen levels. Excess facial hair, known as hirsutism, is a classic sign of virilization. Buffalo hump (B) and truncal obesity (C) are associated with Cushing's syndrome, not virilization. Gonadal atrophy (D) refers to the shrinkage of the gonads and is not a typical feature of virilization.

Correct Answer: B

Rationale: Thyroxine is also known as T4, a thyroid hormone produced by the thyroid gland. It plays a crucial role in regulating metabolism. TSH (Thyroid Stimulating Hormone) is a hormone produced by the pituitary gland to stimulate thyroid hormone production, not thyroxine itself. Choice C is incorrect because thyroxine exerts negative feedback on TSH, not T3. Choice D is incorrect as thyroxine actually increases basal metabolic rate. Thus, the correct answer is B as thyroxine is indeed T4.

Correct Answer: D

Rationale: The correct answer is D. The adrenal cortex secretes cortisol, the pancreas secretes insulin, and the adenohypophysis secretes growth hormone. Cortisol helps regulate metabolism, insulin controls blood sugar levels, and growth hormone stimulates growth. Choice A is incorrect because ADH is not secreted by the adrenal cortex, and aldosterone is not secreted by the pancreas or adenohypophysis. Choice B is incorrect because epinephrine is not secreted by the adrenal cortex, and ACTH is not secreted by the pancreas or adenohypophysis. Choice C is incorrect because androgen is not secreted by the pancreas or adenohypophysis, and ADH is not secreted by the adrenal cortex.