The renal medulla is composed of tissue called ______.

Correct Answer: A

Rationale: Medulla contains renal pyramids not nephrons (units), sinus (cavity), or pelvis (collecting). This defines medullary structure, key for concentration, contrasting with other terms.

Correct Answer: B

Rationale: Kidneys have ~1 million nephrons not 10M, 100K, or 10K. This quantifies functional units, key for filtration capacity, contrasting with over/underestimates.

Correct Answer: B

Rationale: Bladder has 3 orifices: 2 ureters (in), 1 urethra (out) not 2, 4, or 5. This counts openings, vital for anatomy, contrasting with miscounts.

Correct Answer: B

Rationale: Principal cells in the collecting tubule regulate water and salt balance ADH increases water permeability (aquaporins), aldosterone boosts Na reabsorption (e.g., ENaC channels). Intercalated cells focus on acid-base H /HCO₃⁻ secretion. Macula densa cells sense NaCl JGA, not balance. Mesangial cells support glomerulus structural. Principal cells' dual role distinguishes them, critical for osmolality and volume homeostasis, unlike pH, sensing, or support cells.

Correct Answer: B

Rationale: Prostaglandin F causes renal vasoconstriction reduces renal blood flow (RBF) and GFR (e.g., opposes vasodilators). Vasodilation (e.g., PGE/I) increases GFR opposite. Renin release is JGA-driven not direct. No effect ignores its role. Constriction's GFR drop distinguishes it, critical for prostaglandin balance, unlike dilation or neutral effects.