Iodine, colloid, and goiter refer to which gland?

Correct Answer: C

Rationale: The correct answer is C: Thyroid. Iodine is essential for thyroid hormone production. A colloid is a gel-like substance found in the thyroid follicles. Goiter is a condition of thyroid enlargement. The other choices are incorrect because the pancreas (A) produces digestive enzymes and hormones like insulin, the parathyroid (B) regulates calcium levels, and the neurohypophysis (D) is part of the pituitary gland responsible for releasing hormones like vasopressin. Thus, the correct choice is the thyroid gland due to its association with iodine, colloid, and goiter.

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: D

Rationale: The correct answer is D because both Cushing syndrome and Addison's disease are disorders of the adrenal cortex. Cushing syndrome involves excessive cortisol production, while Addison's disease is characterized by insufficient cortisol production. Both conditions directly affect the adrenal cortex, leading to hormonal imbalances. Choice A is incorrect because Cushing syndrome involves hyperfunction, not hypofunction. Choice B is incorrect as it states hypersecretion, which is true for Cushing syndrome but not for Addison's disease. Choice C is incorrect because while replacement cortisol therapy is used for Addison's disease, it is not the only treatment option, and it does not apply to Cushing syndrome.

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.