The excretory system of human beings includes a pair of kidneys, a pair of ureters, a urinary bladder and a urethra.
Urine produced in the kidneys passes through the ureters into the urinary bladder where it is stored until it is released through the urethra.
The process of expelling urine out of the body through urethra by opening the sphincter muscles passing of urine involving relaxation of sphincter muscles between the urinary bladder and urethra is called micturition.