This is the functional unit of the kidney

Correct Answer: C

Rationale: Nephrons filter/form urine not hilum (entry), neurons (nerve), or medulla (region). This defines functional unit, key for physiology, contrasting with structural terms.

Correct Answer: B

Rationale: Sodium is mostly reabsorbed by primary active transport Na /K -ATPase pumps it from tubular cells to blood (e.g., PCT ~65%). Passive diffusion occurs minimally gradient-driven. Secondary active transport aids co-transport (e.g., glucose) not primary. Facilitated diffusion lacks energy insufficient. Active pumping distinguishes it, key to sodium gradient creation, unlike passive or co-transport mechanisms.

Correct Answer: B

Rationale: Afferent/efferent denervation (e.g., cauda equina injury) causes a hypertonic, spasmatic bladder intrinsic smooth muscle overacts, periodic uncontrolled micturition. Sensation loss alone is afferent tonic. Normal reflex needs nerves false. Increased sensation contradicts denervation. Hypertonicity distinguishes it, key to dual nerve loss, unlike single or intact scenarios.

Correct Answer: C

Rationale: Increased glomerular capillary filtration coefficient (Kf) boosts GFR enhances filtration surface/permeability (e.g., Starling forces). Afferent resistance increase lowers flow drops GFR. Efferent resistance decrease reduces pressure lowers GFR. Capsular pressure increase opposes decreases GFR. Kf's enhancement distinguishes it, critical for filtration capacity, unlike resistance or pressure shifts.

Correct Answer: A

Rationale: Bladder stretch increases action potentials from bladder to sacral region afferent nerves signal fullness (e.g., micturition reflex). Parasympathetic is efferent response, not trigger. Somatic motor controls sphincter not stretch. Ascending paths inform brain secondary. Afferent signaling distinguishes it, key to reflex initiation, unlike efferent or higher pathways.