Which of the following statements about the thyroid gland is true?

Correct Answer: D

Rationale: The thyroid, anterior to the trachea and below the larynx, contains embedded parathyroids (posteriorly) and produces three hormones: thyroxine (T4), triiodothyronine (T3), and calcitonin. All statements hold: location aids surgical identification, parathyroids regulate calcium, and hormones manage metabolism/calcium. This comprehensive accuracy distinguishes thyroid anatomy/function, key to endocrine physiology.

Correct Answer: D

Rationale: The renin-angiotensin-aldosterone system (RAAS) raises blood pressure: renin (kidneys) triggers angiotensin II, constricting vessels, and aldosterone, retaining sodium/water. It doesn't lower volume/pressure or raise glucose. Pressure elevation distinguishes RAAS's role, critical for hypotension response, contrasting with glucose or volume reduction effects.

Correct Answer: A

Rationale: The posterior pituitary produces zero hormones it stores and releases ADH and oxytocin, synthesized by hypothalamic neurons, via the hypothalamic-hypophyseal tract. 'One' or 'two' suggest production (e.g., ADH, oxytocin), but neurohypophysis lacks glandular synthesis, unlike anterior pituitary (e.g., TSH). 'Three' exceeds known outputs no third hormone exists. Its role as a neural extension for hypothalamic hormones distinguishes it, key to understanding pituitary division, unlike hormone-generating glands.

Correct Answer: D

Rationale: The pituitary gland is purely endocrine, releasing hormones (e.g., GH, TSH) into blood, lacking exocrine ducts. The pancreas is dual endocrine islets (insulin) and exocrine acini (digestive enzymes). Kidneys are endocrine (erythropoietin, renin) and exocrine (urine via nephrons). Gonads (testes/ovaries) are endocrine (testosterone/estrogen) and exocrine (sperm/eggs via ducts). Pituitary's exclusive endocrine nature distinguishes it, key to its master gland status, unlike dual-function organs.

Correct Answer: D

Rationale: Gigantism, acromegaly, and hyperprolactinemia often stem from pituitary adenomas (tumors), but the question implies adrenal tumors (pheochromocytoma, neuroblastoma) from context. These pituitary conditions aren't adrenal tumors, so 'none' fits if strictly adrenal-focused. This distinction clarifies tumor location, key to differential diagnosis, contrasting with pituitary-derived states.