Learn about urinary system anatomy using interactive pictures supported by thorough descriptions of its function internal structure of human heart pdf the human body. The urinary system consists of the kidneys, ureters, urinary bladder, and urethra.
The kidneys filter the blood to remove wastes and produce urine. The ureters, urinary bladder, and urethra together form the urinary tract, which acts as a plumbing system to drain urine from the kidneys, store it, and then release it during urination. The kidneys are surrounded by a layer of adipose that holds them in place and protects them from physical damage. The kidneys filter metabolic wastes, excess ions, and chemicals from the blood to form urine. Gravity and peristalsis of smooth muscle tissue in the walls of the ureters move urine toward the urinary bladder. The ends of the ureters extend slightly into the urinary bladder and are sealed at the point of entry to the bladder by the ureterovesical valves. These valves prevent urine from flowing back towards the kidneys.
Urine entering the urinary bladder from the ureters slowly fills the hollow space of the bladder and stretches its elastic walls. The walls of the bladder allow it to stretch to hold anywhere from 600 to 800 milliliters of urine. The urethra is also an organ of the male reproductive system as it carries sperm out of the body through the penis. The internal urethral sphincter is made of smooth muscle and opens involuntarily when the bladder reaches a certain set level of distention.