Insulin and glucagon:

Correct Answer: D

Rationale: The correct answer is D because insulin and glucagon are both hormones secreted by the pancreas to regulate blood glucose levels. Insulin is secreted by beta cells in response to high blood glucose levels, promoting glucose uptake by cells. Glucagon is secreted by alpha cells in response to low blood glucose levels, stimulating the release of stored glucose. Choices A and C are incorrect because insulin is secreted by beta cells, not glucagon, and they are secreted in response to high, not low, glucose levels. Choice B is incorrect because insulin lowers blood glucose levels, while glucagon raises them.

Correct Answer: B

Rationale: The correct answer is B: Releasing hormones. Releasing hormones are produced in the hypothalamus and travel through the hypophyseal-hypothalamic portal capillaries to reach the anterior pituitary gland. This is where they stimulate the release of specific hormones. Gonadotropins (A) are produced by the anterior pituitary gland, not found within the portal capillaries. Catecholamines (C) are produced by the adrenal glands, not within the portal capillaries. Mineralocorticoids (D) are steroid hormones produced by the adrenal cortex, not found within the portal capillaries.

Correct Answer: D

Rationale: Step-by-step rationale: 1. The neurohypophysis is the posterior pituitary gland. 2. It stores and releases hormones produced by the hypothalamus. 3. These hormones include oxytocin and vasopressin. 4. These hormones regulate water balance, blood pressure, and uterine contractions. 5. Choice D is correct as it accurately describes the neurohypophysis. Summary: A: Incorrect - Anterior pituitary gland is not the neurohypophysis. B: Incorrect - These hormones are secreted by the anterior pituitary gland. C: Incorrect - Releasing hormones are produced by the hypothalamus, not the neurohypophysis.

Correct Answer: A

Rationale: The correct answer is A: Pancreas. The pancreas secretes insulin to decrease blood glucose levels and glucagon to elevate blood glucose levels. Insulin helps cells absorb glucose for energy, while glucagon triggers the release of stored glucose into the bloodstream. Adenohypophysis (B) secretes various hormones but not related to blood glucose regulation. Thyroid (C) secretes hormones that regulate metabolism, not directly impacting blood glucose levels. Adrenal cortex (D) secretes hormones like cortisol and aldosterone, which are not primarily involved in blood glucose regulation.

Correct Answer: B

Rationale: Step-by-step rationale for why choice B is correct: 1. T3 and T4 are thyroid hormones produced by the thyroid gland. 2. These hormones play a crucial role in regulating the body's metabolism. 3. T3 and T4 directly influence the basal metabolic rate (BMR). 4. An increase in T3 and T4 levels leads to an increase in BMR. 5. Therefore, choice B is correct as T3 and T4 regulate the basal metabolic rate. Summary of why other choices are incorrect: - Choice A (stimulate the adenohypophysis to secrete TSH) is incorrect as TSH is produced by the pituitary gland, not affected by T3 and T4. - Choice C (stimulate osteoclastic activity, thereby elevating plasma calcium levels) is incorrect as this function is primarily attributed to parathyroid hormone, not T3 and T4. - Choice D (all is applicable) is incorrect as only choice B