USR - Urine Transport, Storage, and Elimination Lesson
Urine Transport, Storage, and Elimination
Ureters
The ureters are two tubes that drain urine from the kidneys to the bladder. Each ureter is a muscular tube about 10 inches long that send the urine in small spurts into the bladder.
Bladder
The bladder is a hollow muscular organ shaped like a balloon. It sits in the pelvis and is held in place by ligaments attached to other organs and the pelvic bones. The bladder functions to store urine until you are ready to go to the bathroom to empty it. In a healthy urinary system, the bladder can swell to hold up to 16 ounces comfortably for 2 to 5 hours.
Circular muscles called sphincters control the flow of urine out of the bladder. The sphincter muscles close tightly like a rubber band around the opening of the bladder into the urethra, the tube that allows urine to pass outside the body. Nerves in the bladder tell you when it is time to urinate (empty your bladder). The sensation to urinate becomes stronger as the bladder fills and reaches its limit. Once the bladder is full, nerves from the bladder send a message to the brain that the bladder is full, and the urge to empty your bladder intensifies.
Urethra
When you urinate, the brain signals the bladder muscles to tighten, squeezing urine out of the bladder. At the same time, the brain signals the sphincter muscles to relax. As these muscles relax, urine exits the bladder through the urethra. When all the signals occur in the correct order, normal urination occurs.
Disorders of the Urinary System
Learn about disorders and diseases of the urinary system in the learning object below.
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