What is the function of Prostaglandin F in the regulation of GFR?

Correct Answer: B

Rationale: Prostaglandin F causes renal vasoconstriction reduces renal blood flow (RBF) and GFR (e.g., opposes vasodilators). Vasodilation (e.g., PGE/I) increases GFR opposite. Renin release is JGA-driven not direct. No effect ignores its role. Constriction's GFR drop distinguishes it, critical for prostaglandin balance, unlike dilation or neutral effects.

Correct Answer: D

Rationale: 1% of GFR is excreted ~180 L/day filtered, ~1.8 L urine (e.g., 99% reabsorbed). 99% excreted reverses impossible. 1% reabsorbed understates most returns. 50% reabsorbed halves reality too low. Low excretion distinguishes it, critical for renal efficiency, unlike reversed or understated options.

Correct Answer: D

Rationale: A GFR marker (e.g., inulin) shouldn't be metabolized must stay intact for clearance (e.g., excreted fully). Not secreted ensures filtration-only true. Not reabsorbed keeps GFR accurate correct. Non-toxic is essential safety. Metabolism distinguishes the error, critical for marker purity, unlike filtration-only criteria.

Correct Answer: C

Rationale: CO₂ combining with H₂O via extracellular carbonic anhydrase is false occurs intracellularly (e.g., PCT enzyme). H secretion and H₂CO₃ formation are true HCO₃⁻ reclaimed. Poor permeability holds indirect reabsorption. Intracellular site distinguishes the error, key to bicarbonate mechanism, unlike correct steps.

Correct Answer: C

Rationale: Spironolactone (aldosterone inhibitor) decreases K secretion blocks Na reabsorption, reducing K exchange (e.g., collecting duct). High plasma K increases secretion stimulates. Proximal diuretic (e.g., acetazolamide) raises distal K increases. Alkalosis boosts K secretion H /K shift. Aldosterone block distinguishes it, key to K sparing, unlike secretion-enhancing factors.