Most important buffering system is?

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.

Correct Answer: A

Rationale: Kidneys are retroperitoneal (behind peritoneum) not thoracic (lungs), pelvic (bladder), or pericardial (heart). This positions them anatomically, vital for surgical/radiological context, contrasting with cavity misconceptions.

Correct Answer: B

Rationale: Ureters carry urine from kidneys to bladder not reverse, urethra (exit), or liver (digestive). This specifies transport path, critical for urine flow, contrasting with incorrect directions.

Correct Answer: B

Rationale: Kidney stones form from mineral/salt precipitation not infection, dehydration (risk factor), or BP alone. This specifies etiology, critical for prevention, contrasting with secondary factors.

Correct Answer: B

Rationale: Polyuria is excess urine not anuria (none), oliguria (low), or nocturia (night). This defines high output, critical for diabetes detection, contrasting with reduced states.