Which structure transports urine from the kidney to the bladder?

• A. Renal pelvis
• B. Renal artery
• C. Urethra
• D. Ureter

Answer: (D)

Urine travels from the kidney to the bladder through the ureter. The ureter is a muscular tube that uses rhythmic contractions, called peristalsis, to push urine downward from the renal pelvis of the kidney into the bladder. It runs behind the peritoneum (retroperitoneally) and connects each kidney to the bladder, with urine entering the bladder through the ureteric openings. A one-way mechanism at this junction helps prevent backflow. The renal pelvis, inside the kidney, collects urine before it enters the ureter, but does not transport it all the way to the bladder. The renal artery supplies blood to the kidney, not urine transport, and the urethra carries urine from the bladder to the outside of the body, not from kidney to bladder.