Your urinary tract helps to get rid of urine (your body's liquid waste). The kidneys collect unneeded chemicals and water, making urine. Urine travels through the ureters to the bladder. The bladder fills with urine, holding it until you're ready to release it. The urethra is the canal that carries urine from the bladder out of the body. Signals from the brain tell the sphincter (muscles around the opening of the bladder) when to let urine flow out of the body.