The urinary system consists of the kidneys, ureters, bladder, urethra, and sphincter muscles. The kidneys filter waste from the bloodstream and produce urine. The ureters carry urine from the kidneys to the bladder, which stores urine until urination. During urination, signals cause the bladder to contract and the sphincter muscles to relax, releasing urine through the urethra. The typical adult produces around 1.5 quarts of urine per day to remove waste from the body.