(i) Kidney: Kidneys filter the blood and remove the nitrogenous wastes and other toxic substances from the blood and help in urine formation.
(ii) Ureter: These are a pair of muscular tubes which are thin and come out of the kidneys. The main function of the ureters is to pass urine from the kidney to the urinary bladder.
(iii) Urinary bladder: This is a muscular sac-like structure that stores urine. When it is completely filled, the urine is expelled through the urethra.
(iv) Urethra: This is the structure that is connected to the urinary bladder and expels urine from the body. In males, it is the common route for the sperms and urine. The urethra is guarded by the sphincters.