Which organ stores urine?

• A. Ureter
• B. Kidney
• C. Urinary bladder
• D. Urethra

Answer: (C)

The urinary bladder stores urine. It’s a stretchy, muscular sac that holds urine produced by the kidneys until you’re ready to urinate. As the bladder fills, stretch receptors trigger a reflex that allows the bladder to accommodate more urine by relaxing the detrusor muscle. When you choose to urinate, the detrusor muscle contracts and the urethral sphincters relax to let urine pass through the urethra.

The other structures have different roles: the ureter carries urine from the kidneys to the bladder; the kidney forms urine through filtration and processing of blood; the urethra carries urine out of the body.