With regard to the renin-angiotensin system

Correct Answer: C

Rationale: Angiotensinogen, synthesized by the liver, is cleaved by kidney-derived renin to angiotensin I, driving blood pressure regulation via angiotensin II. Prorenin is largely inactive, not 50% active. Propranolol (β-blocker) reduces renin by blocking sympathetic stimulation, not increasing it. Angiotensin I is inactive, not a vasodilator angiotensin II vasoconstricts. Liver synthesis distinguishes angiotensinogen's role, essential for RAAS activation, unlike precursor activity, drug effects, or vasodilation errors.

Correct Answer: C

Rationale: ANP inhibits ADH secretion, promoting diuresis to lower volume/BP, countering ADH's water retention. It reduces BP, not increases, via vasodilation/natriuresis. Dopamine responsiveness isn't ANP-mediated ANP acts via cGMP. ANPR-A (active) has higher affinity than ANPR-C (clearance). ADH inhibition distinguishes ANP's role, key to fluid regulation, unlike BP, dopamine, or receptor claims.

Correct Answer: D

Rationale: Bacterial toxins (e.g., LPS) act on the organum vasculosum lamina terminalis (OVLT), releasing pyrogens (IL-1) to raise hypothalamic setpoint, causing fever immune-thermoregulation link. Sweat vaporization is ~20-30% heat loss (radiation dominates). TSH rises in chronic cold, not acutely significant. Anterior hypothalamus cools posterior triggers shivering. OVLT mediation distinguishes fever, key to infection response, unlike sweat, thyroid, or regional errors.

Correct Answer: C

Rationale: Hypothalamus regulates renal function via ADH (water balance) and RAAS (blood pressure) essential for kidney homeostasis. Movement (basal ganglia/cerebellum) and visual acuity (occipital cortex/optic nerve) aren't hypothalamic renal control is. Its endocrine-renal link distinguishes it, critical for fluid/pressure regulation, unlike motor or sensory roles.

Correct Answer: C

Rationale: The anterior pituitary is regulated by hypothalamic releasing hormones (e.g., TRH, GHRH) via the hypophyseal portal system, not muscle, peripheral nerves, thalamus, or CSF directly. This hypothalamic control distinguishes it as the endocrine 'master gland' coordinator, critical for thyroid, adrenal, and growth functions, contrasting with unrelated physiological triggers.