Which of the following tends to decrease potassium secretion by the cortical collecting tubule?

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: 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: B

Rationale: At 5000 m, hypoxia drives hyperventilation PCOâ‚‚ falls (COâ‚‚ blown off), pH rises (respiratory alkalosis). Both lower misstates pH rises. Both higher ignores altitude false. pH fall/PCOâ‚‚ rise is hypoventilation opposite. Alkalotic shift distinguishes it, key to high-altitude response, unlike uniform or reversed changes.

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.