With regard to adrenal function

Correct Answer: B

Rationale: Adrenal medulla, secreting epinephrine/norepinephrine, isn't essential life persists post-adrenalectomy with cortical steroids. Zona fasciculata secretes cortisol, not aldosterone (glomerulosa). ACTH mainly controls cortisol, not glomerulosa's aldosterone (angiotensin II does). Medullary secretion is ~80% epinephrine, not norepinephrine. Non-essentiality distinguishes medulla, key to understanding adrenal roles, unlike zonal, control, or output errors.

Correct Answer: A

Rationale: PTH decreases serum PO₄ by increasing renal excretion, raising Ca²⁺ net effect is PO₄ reduction. Vitamin D increases Ca/PO₄ absorption, reducing excretion opposite claim. Calcitonin is from thyroid C-cells, not parathyroid. Insulin promotes bone formation (anabolic), not decreases. PTH's PO₄-lowering distinguishes it, key to calcium-phosphate regulation, unlike vitamin D, calcitonin, or insulin errors.

Correct Answer: C

Rationale: Oestrogen inhibits osteoclasts, reducing bone resorption, preserving mass post-menopause osteoporosis link. Ca is ~1-2% body mass, not 15%. Intestinal Ca absorption is active (vitamin D), not passive. Corticosteroids inhibit osteoblasts, promoting loss. Oestrogen's osteoclast suppression distinguishes it, key to bone health, unlike mass, absorption, or steroid errors.

Correct Answer: D

Rationale: Local hormones and paracrine hormones act on nearby cells without bloodstream travel e.g., prostaglandins (local) or growth factors (paracrine). Autocrine hormones target the secreting cell, circulating hormones travel via blood (e.g., insulin). 'Both 1 and 2' (local and paracrine) fits, as both share this localized action. This distinguishes short-range endocrine signaling, key to tissue-specific responses like inflammation, contrasting with systemic hormone effects.

Correct Answer: C

Rationale: An antagonistic effect occurs when one hormone opposes another e.g., insulin lowers glucose, glucagon raises it not synergistic (cooperative), permissive (enabling), circulating (delivery), or local (proximity). This opposition distinguishes endocrine balance, vital for homeostasis, contrasting with cooperative or static effects.