Normally, a person has two kidneys Kidneys The kidneys are bean-shaped organs that figure prominently in the urinary tract. Each is about 4 to 5 inches (12 centimeters) long and weighs about one third of a pound (150 grams). One lies... read more . The rest of the urinary tract consists of the following:
The bladder Bladder The bladder is an expandable, muscular sac. Urine accumulates in the bladder as it arrives from the ureters. The bladder gradually increases in size to accommodate an increasing volume of urine... read more (an expandable muscular sac that holds urine until it is released from the body)
The urethra Urethra The urethra is a tube that drains urine from the bladder out of the body. In men, the urethra is about 8 inches (20 centimeters) long, ending at the tip of the penis. In women, the urethra is... read more (a tube attached to the bladder that leads to the outside of the body)
Each kidney continuously produces urine, which then drains through the ureter into the bladder at a low pressure. From the bladder, urine drains through the urethra and exits the body through the penis in males and at the vulva (the area of the external female genital organs) in females. Usually, urine is free of bacteria and other infectious organisms.