Which of the following is descriptive of the adrenal cortex?

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).

Correct Answer: C

Rationale: The correct answer is C because epinephrine stimulates the hepatic conversion of glycogen into glucose. This process, called glycogenolysis, releases stored glucose from the liver into the bloodstream, increasing blood glucose levels. Choice A is incorrect because epinephrine does not directly increase glucose transport into cells. Choice B is incorrect as gluconeogenesis is the synthesis of new glucose, not the release of stored glucose. Choice D is incorrect because fatty acids are not directly converted into glucose by epinephrine.

Correct Answer: A

Rationale: Step 1: Calcitonin is secreted by the thyroid gland and lowers blood calcium levels by promoting calcium deposition in bones. Step 2: Parathyroid hormone (PTH) is secreted by the parathyroid gland and raises blood calcium levels by stimulating bone resorption and increasing calcium reabsorption in the kidneys. Step 3: Since Calcitonin lowers blood calcium and PTH raises blood calcium, choice A is correct. Summary: Choices B, C, and D are incorrect as they provide inaccurate information about the roles of calcitonin, PTH, thyroxine, and triiodothyronine in regulating blood calcium levels.

Correct Answer: D

Rationale: The correct answer is D: pituitary gland. The pituitary gland is often referred to as the 'master gland' because it controls the functions of other endocrine glands in the body. It secretes hormones that regulate various bodily functions such as growth, metabolism, and reproduction. It is located at the base of the brain and is divided into two parts: anterior and posterior. The anterior pituitary gland produces and releases several important hormones that influence other endocrine glands. The other choices (A: pancreas, B: adrenal glands, C: thyroid gland) do not have the same broad regulatory control over the endocrine system as the pituitary gland.

Correct Answer: A

Rationale: The correct answer is A: ADH (Antidiuretic Hormone). ADH is released in response to a nerve impulse to regulate water balance in the body by increasing water reabsorption in the kidneys. Nerve impulses trigger the release of ADH from the posterior pituitary gland. Cortisol (B) is released in response to stress, testosterone (C) is a sex hormone, and insulin (D) is released in response to high blood sugar levels, not nerve impulses.