Which among the following is known as the smallest gland in the human body?

Correct Answer: B

Rationale: The pineal gland, at 5-8 mm in the brain's epithalamus, is the smallest endocrine gland, producing melatonin for sleep regulation. The pituitary (larger, pea-sized) controls other glands, parotid (salivary) and Ebner's (tongue) are exocrine not endocrine. Pineal's diminutive size and endocrine role distinguish it, vital for circadian rhythms, contrasting with larger or ducted glands.

Correct Answer: D

Rationale: Angiotensin II stimulates ADH (vasopressin) release from the posterior pituitary, enhancing water retention to raise blood volume in hypovolemia. Alcohol inhibits ADH, causing diuresis. Carbamazepine can increase ADH (SIADH risk), but isn't primary. High ECF volume suppresses ADH via stretch receptors. Angiotensin II's role distinguishes it, key to RAAS-ADH synergy, unlike inhibitory or secondary triggers.

Correct Answer: D

Rationale: GLUT2 in β-cells allows glucose entry, triggering insulin release via metabolism and Ca²⁺ high capacity, low affinity fits pancreas. Insulin inhibits ketogenesis, not increases release. It's from β-cells, not A (alpha, glucagon). cAMP (e.g., glucagon) doesn't drive insulin glucose metabolism does. GLUT2's role distinguishes it, critical for insulin secretion, unlike ketone, cell, or signaling errors.

Correct Answer: D

Rationale: Glucocorticoids (e.g., cortisol) promote gluconeogenesis, support myocardial contractility (via catecholamine sensitivity), and inhibit glucose uptake (insulin resistance), but don't decrease vascular resistance they maintain or increase it via permissive effects on angiotensin II/vasopressors. Decreased resistance aligns with ANP/vasodilators, not cortisol. Vascular support distinguishes glucocorticoid action, critical for stress response, unlike metabolic or cardiac roles.

Correct Answer: A

Rationale: Insulin increases amino acid uptake into cells, promoting protein synthesis anabolic role. It enhances K⁺ uptake (with glucose), not reduces key in hyperkalemia treatment. Absorption varies by injection site (e.g., abdomen faster than thigh). It inhibits protein catabolism, not increases. Amino acid uptake distinguishes insulin's growth function, critical for metabolism, unlike K⁺, pharmacokinetics, or catabolic claims.