The primary function of the ascending loop of Henle in the kidney is?

Correct Answer: A

Rationale: Ascending loop actively reabsorbs Na+ (Na+/K+/2Cl- pump) not Cl- alone, or passive K+/urea. This specifies diluting role, key for concentration gradient, contrasting with passive processes.

Correct Answer: D

Rationale: Kidneys span T12 to L3 not higher thoracic or extended lumbar. This specifies position, vital for radiology, contrasting with incorrect spans.

Correct Answer: C

Rationale: The distal convoluted tubule excels in secretion lacks microvilli (reabsorption-focused), emphasizing secretion (e.g., H , K ) via active transport. The proximal tubule dominates reabsorption ~65% of filtrate (e.g., glucose, Na ) but secretes organics (e.g., creatinine). The Loop of Henle focuses on concentration minimal secretion. The collecting duct adjusts urine via reabsorption/secretion (e.g., H by intercalated cells) less secretion-centric. The distal tubule's secretion role, tied to fine-tuning ion balance, distinguishes it, critical for acid-base and potassium regulation, unlike reabsorption-heavy or concentration-focused segments.

Correct Answer: B

Rationale: Tubular secretion is the selective transfer from peritubular capillaries to the tubular lumen removes waste (e.g., H , drugs) into urine. Lumen-to-capillary is reabsorption opposite. Reabsorption conserves e.g., glucose. Filtration occurs at glomerulus not tubular. Selective capillary-to-lumen movement distinguishes it, critical for excretion, unlike reabsorption or filtration processes.

Correct Answer: C

Rationale: Glucose reabsorption is secondary active transport (SGLT) from lumen to cell Na gradient-driven then passive (GLUT) to capillary (e.g., PCT). Passive diffusion alone can't reclaim energy needed. Primary active transport is Na not glucose directly. Full active transport overstates capillary step passive. Dual mechanism distinguishes it, critical for efficient glucose recovery, unlike single-mode errors.