The only hormone that lowers blood glucose levels is:

Correct Answer: B

Rationale: The correct answer is B: insulin. Insulin is produced by the pancreas and helps lower blood glucose levels by promoting the uptake of glucose into cells for energy or storage. Glucagon (A) raises blood glucose levels, epinephrine (C) and cortisol (D) also increase blood glucose levels by stimulating the release of glucose from storage sites.

Correct Answer: A

Rationale: The correct answer is A because the hypothalamus secretes releasing hormones into the portal capillaries, which then travel to the anterior pituitary to regulate hormone secretion. This is known as the hypothalamic-pituitary axis. Choices B and C are incorrect because the hypothalamus is not composed of glandular tissue and it is not called the adenohypophysis. Choice D is incorrect because the connection between the hypothalamus and the neurohypophysis is via the hypothalamic-hypophyseal tract, not through the portal capillaries.

Correct Answer: D

Rationale: The correct answer is D because a deficiency of dietary iodine leads to an insufficient production of thyroid hormones, which can result in the enlargement of the thyroid gland, known as a goiter. This is due to the thyroid gland working harder to try to produce more hormones. A, B, and C are incorrect because a deficiency of dietary iodine does not directly affect plasma calcium levels, blood volume, or the synthesis of calcitonin. These are functions that are primarily regulated by other hormones and factors in the body, not by iodine deficiency.

Correct Answer: A

Rationale: The correct answer is A because the posterior pituitary gland is an extension of the hypothalamus. The hypothalamus produces hormones that are stored and released by the posterior pituitary gland. This connection between the two structures allows for direct neural control over hormone release. Option B is incorrect because the neurohypophysis does not secrete releasing hormones; rather, it releases hormones produced by the hypothalamus. Option C is incorrect because the posterior pituitary gland does not regulate adenohypophyseal function; instead, it stores and releases hormones produced by the hypothalamus. Option D is incorrect because the posterior pituitary gland does not secrete releasing hormones; it releases hormones produced by the hypothalamus.

Correct Answer: B

Rationale: The correct answer is B because a hormone that suppresses gluconeogenesis helps to prevent hyperglycemia by inhibiting the production of glucose in the liver. This hormone regulates blood sugar levels by reducing the formation of new glucose molecules. Choice A is incorrect because increasing renal excretion of sodium and water is related to the regulation of fluid balance, not gluconeogenesis. Choice C is incorrect because causing diuresis involves increasing urine production and is not directly related to suppressing gluconeogenesis. Choice D is incorrect because causing hypocalcemia refers to low levels of calcium in the blood and is not associated with the suppression of gluconeogenesis.