Insulin secretion is stimulated by all of the following except

Correct Answer: C

Rationale: Noradrenaline (via α2-receptors) inhibits insulin secretion, prioritizing glucose mobilization in stress. Mannose (metabolized like glucose), glucagon (short-term β-cell boost), and leucine (amino acid trigger) stimulate insulin. Noradrenaline's suppression distinguishes it, critical for sympathetic-glucose balance, unlike stimulatory sugars, hormones, or amino acids.

Correct Answer: D

Rationale: Calcitriol (active vitamin D) raises blood calcium by enhancing absorption, though not a thyroid hormone calcitonin (thyroid-produced) lowers it, while T3/T4 regulate metabolism, TRH/TSH stimulate thyroid. Context suggests calcitonin intent, but 'D' (calcitriol) aligns with calcium regulation broadly. This distinguishes calcium homeostasis, vital for bone and nerve function, contrasting with thyroid's metabolic focus.

Correct Answer: D

Rationale: Parathyroid glands (often labeled 'E' in diagrams) secrete PTH to raise blood calcium, unlike thyroid (calcitonin, lowers) or others. 'E' aligns with prior answer. This distinguishes PTH's role in calcium homeostasis, vital for nerve and bone function, contrasting with metabolic glands.

Correct Answer: A

Rationale: Cortisol from zone 'B' (fasciculata) resists stress and raises glucose via gluconeogenesis, not sympathetic (medulla) or glycogenolysis (glucagon/epinephrine). This distinguishes cortisol's chronic stress function, vital for energy, contrasting with acute responses.

Correct Answer: C

Rationale: Acromegaly from pituitary hGH excess in adulthood causes bone thickening, not goiter (thyroid), Graves' (thyroid), Cushing's (cortisol), or gigantism (childhood). This distinguishes acromegaly's adult phenotype, critical for diagnosis, contrasting with childhood growth or thyroid disorders.