Which of the following is correct regarding glomerular filtration rate?

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: 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.

Correct Answer: C

Rationale: Angiotensin II receptors are in the zona glomerulosa stimulate aldosterone release (e.g., adrenal cortex). Juxtaglomerular cells produce renin not receptors. Macula densa senses lacks these. Intercalated cells manage pH not angiotensin. Adrenal location distinguishes it, key to RAAS, unlike renal or tubular sites.

Correct Answer: C

Rationale: The bicarbonate buffer system is most important rapidly neutralizes H (e.g., CO₂/HCO₃⁻ in blood). Bone buffers chronically slow. Phosphate is secondary intracellular/tubular. Proteins assist less capacity. Bicarbonate's speed distinguishes it, key to acute pH control, unlike slow or secondary systems.