Wastes and toxic that the human body produces, which is a lot, can be very toxic if they remain in the body. These substances are removed from the body via the urinary system. The kidneys act like filters which filters the waste from the blood. The urinary system starts at the kidneys. This waste is then sent through the ureters into the bladder which is like a storage area which can be voluntarily controlled. At the bottom of the bladder is a muscle called the sphincter which acts as an outlet valve, which is controlled by the brain. At the bottom of the bladder When the bladder is full, it sends a signal to the brain that it is full and then the brain prompts the sphincter to open, thereby releasing the urine.