The functional structure of the kidney is the

Correct Answer: D

Rationale: The nephron is the kidney's functional unit filters, reabsorbs, secretes (e.g., ~1 million/kidney). Neurons are neural not renal. Sinusoids are liver not kidney. Trigone is bladder not functional unit. Nephron's role distinguishes it, key to kidney function, unlike unrelated structures.

Correct Answer: A

Rationale: The ascending limb is water-impermeable pumps NaCl, concentrating medulla (e.g., countercurrent multiplier). Descending is permeable water exits. Thick/thin are subsets ascending key. Impermeability distinguishes it, critical for urine concentration, unlike permeable or vague options.

Correct Answer: D

Rationale: The hypothalamus monitors blood osmolarity osmoreceptors trigger ADH (e.g., water balance). JGA senses pressure not osmolarity directly. Medulla oblongata is respiratory not osmotic. Midbrain is motor unrelated. Hypothalamus's osmotic role distinguishes it, critical for hydration, unlike pressure or neural sites.

Correct Answer: B

Rationale: Cystitis is bladder infection e.g., E. coli common (mucosa). Urethritis is urethra not bladder. Pyelonephritis is kidney higher. Nephritis is inflammation not specific infection. Cystitis's location distinguishes it, critical for bladder pathology, unlike adjacent or vague terms.

Correct Answer: C

Rationale: Juxtaglomerular (JG) cells secrete renin e.g., JGA responds to low BP. Macula densa senses NaCl signals JG, doesn't secrete. Glomerular epithelial (podocytes) filter not secrete. Basement membrane is structural not cellular. JG's renin role distinguishes it, key to RAAS, unlike sensing or structural parts.