Urinary bladder

The urinary bladder is the organ that collects urine excreted by the kidneys before disposal by urination. A hollow muscular, and distensible (or elastic) organ, the bladder sits on the pelvic floor. Urine enters the bladder via the ureters and exits via the urethra. It's almost impossible to give an exact measurement for the volume of the human bladder, but different sources mention 500 mL (~17 oz) to 1000 mL (~34 oz).

Histologically the bladder contains transitional epithelium, similar to the ureters. The smooth muscle in the bladder is the detrusor muscle.