The urinary tract system is a group of organs of the body, which are responsible for the excretion of urine. In humans, the urinary system includes 2 kidneys, a pair of tube-like structures, called the ureters, which connect the kidneys to the bladder. The bladder is connected to the urethra, which delivers the urine to the outside of the body. The primary function of the urinary tract system is to remove substances from the blood, to form urine and help to regulate various metabolic processes.