Which of the following is a protein made by the kidney?

Correct Answer: D

Rationale: Erythropoietin is a kidney-made protein produced by peritubular cells (e.g., hypoxia-driven anemia correction). Angiotensin is from angiotensinogen liver, converted renally. Mesangial matrix is structural not protein. Creatinine is muscle waste not synthesized. Erythropoietin's renal origin distinguishes it, key to hematopoiesis, unlike precursors, structures, or wastes.

Correct Answer: A

Rationale: First micturition reflex stimulation is at 150 mL initial urge from stretch (e.g., afferent signal). 300 mL is fullness later. 400 mL discomfort escalated. 560 mL exceeds typical late. Early trigger distinguishes it, critical for reflex onset, unlike higher volumes.

Correct Answer: C

Rationale: Peptides are reabsorbed via endocytosis PCT engulfs small proteins (e.g., filtered peptides), energy-dependent. Facilitated diffusion suits glucose not peptides. Active transport is Na not engulfing. Passive diffusion lacks mechanism insufficient. Endocytosis distinguishes it, critical for protein recovery, unlike diffusion or pump methods.

Correct Answer: B

Rationale: The thin descending limb is water-permeable, ion-impermeable osmosis concentrates filtrate (e.g., countercurrent). PCT is leaky ions/water pass. Cortical collecting duct adjusts with ADH ions move. Thick ascending pumps ions water-impermeable. Unique permeability distinguishes thin descending, critical for gradient, unlike leaky or adjustable segments.

Correct Answer: C

Rationale: ADH won't stop diuresis in nephrogenic diabetes insipidus tubules resist (e.g., receptor defect). Lack of ADH responds diabetes insipidus. Excess water dilutes ADH corrects. Combined is treatable ADH works. Resistance distinguishes it, critical for ADH failure, unlike responsive causes.