What anatomical structure prevents reflux of urine into the ureters?

Correct Answer: A

Rationale: The trigone, a triangular area in the bladder base between ureteral openings and urethra, prevents urine reflux into the ureters (A) via ureterovesical junction valves. The renal capsule (B) encases the kidney, nephron (C) filters blood, and urethral sphincter (D) controls outflow, making A correct.

Correct Answer: D

Rationale: Parathyroid hormone (PTH) decreases phosphate reabsorption (E, reassigned as D) in the proximal tubule, increasing urinary phosphate to regulate calcium. It doesn't affect water (A), sodium (B), or form AII (C), making D correct.

Correct Answer: D

Rationale: Glucose appears in urine (glycosuria) when its plasma level exceeds the renal threshold (~180 mg/dL), saturating PCT carriers (D). It's not normal (A), unrelated to angiotensin II (B), and hypoglycemia (C) reduces glucose, making D the cause.

Correct Answer: D

Rationale: Podocytes form the visceral layer of Bowman's capsule (D), surrounding glomerular capillaries to filter plasma. Nephron (A) is broader, glomerulus (B) is capillaries, and renal capsule (C) is outer, making D precise.

Correct Answer: D

Rationale: The loop of Henle (D) extends into the renal medulla, aiding concentration. Pacemaker cells (A) are cardiac, islets (B) are pancreatic, and DCT (C) is cortical, making D the medullary structure.