How does the urinary system normally work?

The job of your urinary system is to remove waste products from your blood and help maintain the proper balance of salts and water in your body. The kidneys and ureters constitute the upper urinary system, and the bladder and urethra make up the lower urinary tract. Your kidneys filter your blood and create urine to carry away the waste. Urine is a mixture of water, salts, and urea (a waste product produced from protein metabolism). It leaves the kidneys via the ureters, the muscular tubes that deliver urine to the bladder in small, steady amounts.
Your kidneys are two purplish-brown organs below your ribs toward the middle of your back. They filter extra fluids, salts, and waste products from your blood to form urine.

Urine flows through narrow tubes called ureters to the bladder.

The bladder stores urine. When you urinate, it squeezes to send the urine through your urethra and out of your body.

The urinary system works the same for men and women.
For normal urination, all parts of the urinary system must work together. Here is how the urinary system works:
  • Urine is made in the kidneys
  • Urine leaves the kidneys, flowing down a pair of long tubes to the bladder.
  • The bladder expands to hold the urine.
  • When the bladder is about 1/3 full, nerve signals are sent to the brain.
  • The brain tells the bladder it’s time to remove the urine.
  • Nerve signals help certain muscles relax. These include the pelvic floor muscles and the urinary sphincter muscles.
  • The bladder muscles contract, forcing urine out through a short tube called the urethra.
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