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urinary bladder n.
A musculomembranous elastic receptacle in the anterior part of the pelvic cavity serving as the temporary storage place for urine.
in most vertebrates, except birds, organ for the temporary storage of urine from the kidneys, connected to the kidneys by means of tubular structures called ureters. A urinary bladder is present in fish as an expansible part of the urinary duct, in amphibians and bladder-possessing reptiles (Sphenodon, turtles, most lizards) as a pocket in the cloaca. In mammals it is a greatly expandible muscular sac. The bladder of an average adult human is uncomfortably distended at a volume of around 350 millilitres (13 quart) of urine.