In calcium metabolism

Correct Answer: D

Rationale: PTH increases urinary PO₄ excretion by inhibiting reabsorption, lowering serum PO₄ while raising Ca²⁺. Gastrin/glucagon/secretin don't notably inhibit calcitonin calcium does. Calcitonin's half-life is ~10 minutes, not 30. Calcitonin reduces bone resorption, not increases. PTH's phosphate effect distinguishes it, key to calcium-phosphate balance, unlike hormonal, kinetic, or resorption errors.

Correct Answer: A

Rationale: Diabetes insipidus (low ADH) causes polyuria (water loss) and polydipsia (thirst) due to dilute urine classic signs. Alcohol inhibits ADH, increasing urine output. Surgical stress boosts ADH (stress response). ADH presence in mammals (e.g., hippos) is universal for water balance. Polydipsia/polyuria distinguish DI, key to its pathophysiology, unlike alcohol, stress, or species claims.

Correct Answer: A

Rationale: Thyroid hormones (T3/T4) lower plasma cholesterol by enhancing LDL receptor clearance, not increase false claim. They boost Na/K ATPase (metabolism), β-receptors (catecholamine sensitivity), and calorigenesis (heat production). Cholesterol reduction distinguishes thyroid action, key to lipid metabolism, unlike metabolic, receptor, or heat truths.

Correct Answer: C

Rationale: Hormone secretion is typically triggered by nervous signals (e.g., hypothalamus to pituitary), blood chemistry (e.g., glucose for insulin), or other hormones not mechanical stretching, which suits exocrine glands (e.g., salivary). The cutoff omits options, but 'mechanical stretching' (C) is least endocrine-relevant per prior answer. This distinction underscores endocrine reliance on systemic cues, vital for coordinated responses, contrasting with mechanical triggers in other systems.

Correct Answer: A

Rationale: ADH secretion from the posterior pituitary adjusts to blood osmotic pressure high osmolarity (dehydration) increases ADH to retain water, not calcium, oxygen, or glucose directly. This osmoregulatory role distinguishes ADH, critical for fluid balance, contrasting with unrelated metabolic triggers.