The Urinary System consists of paired kidneys, ureters, a urinary bladder, and a urethra. The kidneys filter waste from the blood to produce urine. Urine travels from the kidneys down the ureters into the bladder, where it is stored until excretion through the urethra. The main functions of the Urinary System are to filter the blood, regulate water and electrolyte balance, and dispose of nitrogenous wastes.