The excretory system removes waste from the body through the kidneys, ureters, bladder, and urethra. The kidneys filter waste from the blood and produce urine, which travels through the ureters to the bladder. The bladder stores urine until it is released through the urethra. Problems can include urinary tract infections, kidney stones, and cystitis. If the excretory system fails, dangerous waste products remain in the body.