Two ureters convey urine from the kidneys to the bladder.

The ureters are narrow tubes which are about 300 mm long and 5mm wide.

The bladder is a hollow muscular organ that acts as a reservoir for the urine. It is able to distend and normally holds up to 500 ml of urine. As the bladder fills, its walls are stretched.

When the pressure in the bladder is raised to a certain level, nerve impulses pass to the spinal cord and then onto the brain where they are interpreted as a desire to urinate.