The urinary system is responsible for filtering the blood, excreting wastes, and helping to regulate electrolyte and water balance. The urinary system includes the kidneys, ureters, urinary bladder, a...The urinary system is responsible for filtering the blood, excreting wastes, and helping to regulate electrolyte and water balance. The urinary system includes the kidneys, ureters, urinary bladder, and urethra; the bladder and urethra are the most common sites of infection. Common sites of infection in the male reproductive system include the urethra, as well as the testes, prostateand epididymis. The commons sites of infection in females are the vulva, vagina, cervix, and fallopian tubes.