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

Correct Answer: C

Rationale: Potassium secretion in the cortical collecting tubule by principal cells is driven by aldosterone, which increases Na⁺ reabsorption and K⁺ secretion. Spironolactone, an aldosterone antagonist, inhibits this, reducing K⁺ secretion. High plasma K⁺ (A) and alkalosis (D) increase secretion, and diuretics like furosemide (B) indirectly enhance it, making C the correct inhibitor.

Correct Answer: B

Rationale: Paternalism (B) occurs when others (e.g., family) assume decision-making authority, believing they know best, overriding patient autonomy. Justice (A) involves fairness, pragmatism (C) practicality, and veracity (D) truthfulness, none of which fit this assumption of control without patient input, making B correct.

Correct Answer: B

Rationale: Erythropoietin (EPO) release by kidney interstitial cells is triggered by low blood oxygen levels (B) (hypoxia), stimulating red blood cell production in bone marrow to improve oxygen delivery. High oxygen (A) or RBCs (C) suppress it, and COâ‚‚ (D) isn't the trigger, making B correct.

Correct Answer: D

Rationale: Solute uptake and oncotic pressure drive water reabsorption (A), Na/H antiports facilitate sodium and water movement (B), and aquaporin-1 enables water flow (C). All are true—solutes and pressure pull water, Na/H links sodium to water, and aquaporins allow passage—making E (all are correct), reassigned as D, correct.

Correct Answer: A

Rationale: Antifreeze (ethylene glycol) causes metabolic acidosis. Kidneys primarily excrete excess H⁺ via ammonium (NH₄⁺) excretion (A), buffering and eliminating acid in urine. Phosphates (B) help, hyperventilation (C) is respiratory, and free H⁺ (D) is minimal, making A the main mechanism.