The hormone that maintains blood sugar level is secreted by which gland?

Correct Answer: C

Rationale: The pancreas secretes insulin and glucagon to maintain blood sugar: insulin lowers it by promoting uptake, glucagon raises it via liver glucose release. Pineal (melatonin), pituitary (GH, ACTH), and adrenal (adrenaline) glands affect metabolism indirectly not sugar directly. Pancreas's dual hormonal role distinguishes it, key to glucose homeostasis, contrasting with stress or growth regulators.

Correct Answer: D

Rationale: Erythropoietin (EPO) production from kidneys is inhibited by theophylline (adenosine antagonist), reducing RBC stimulation in hypoxia. It increases RBC via progenitor division, but takes days, not 24 hours. Inactivation is hepatic/renal, not spleen-specific. Theophylline's suppression distinguishes it, critical for EPO regulation, unlike action, inactivation, or timing claims.

Correct Answer: D

Rationale: PTH inhibits PO₄ reabsorption (increases excretion) in kidneys, lowering serum PO₄ while raising Ca²⁺ dual action defines it. PTH increases Ca reabsorption, not decreases. PO₄ secretion rises, not falls. Calcitonin reduces bone resorption. PTH's PO₄ effect distinguishes it, critical for calcium-phosphate balance, unlike Ca reabsorption, secretion, or calcitonin errors.

Correct Answer: D

Rationale: Prostaglandins (e.g., PGE2) increase renin secretion, enhancing RAAS in low perfusion/stress. Renin converts angiotensinogen to angiotensin I, but angiotensin II triggers aldosterone indirect. Conversion occurs in blood (renin), not lungs (ACE to angiotensin II). High Na at macula densa suppresses renin. Prostaglandin stimulation distinguishes it, critical for RAAS activation, unlike indirect, site, or Na errors.

Correct Answer: D

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.