Facts About the Urinary System

Your urinary system runs from your urethra to your kidneys and includes all the structures and organs in between. The main purpose of the urinary system is to remove waste products from your body and excrete them from your body. To get that done, it uses five major structures: the urethra, the sphincter muscles, the bladder, the ureters and the kidneys.

Urethra

The urethra is the tube through which urine is expressed from your bladder. The urethra is the last stop for urine, but it is often the first stop in a urinary infection because the opening is exposed to bacteria, such as E. coli. Urethras are present in both men and women, but in men they are also a part of the reproductive system. Semen exits the man's penis through his urethra. A woman's urethra can be between 1 and 2 inches long, but a man's urethra can be as long as 8 inches. This contributes to a woman's risk factor for urinary tract infections.

Sphincter

When the urinary system is described, the sphincter is often left out. However, the sphincter muscles are essential to the urination process, which is the entire function of the urinary system. The sphincter is a circular muscle that wraps around the bladder where it connects to urethra. Its purpose is to keep the connection closed so that urine does not leak out of the bladder. When the nerves in your bladder tell your brain it is time to release the urine, the brain signals the bladder muscles to contract while telling the sphincter muscles to relax. This is how urine is expelled from your body.

Bladder

The urinary bladder (often just called the bladder) is the urine storage area. It is a hollow, balloon-shaped structure that swells as it fills with urine. Depending on your size or age, your bladder can hold about 2 cups of urine for between 2 and 5 hours at a time. Bladder infections and other conditions cause it to hold less urine for less time. When it is time to release your urine, the bladder muscles contract, forcing the urine through the urethra and out of the body.

Ureter

There are two 8- to 10-inch-long tubes called ureters in the urinary system, one for each kidney. The kidneys produce urine, and the ureters transport that urine to the bladder for storage. Ureters are lined with muscles that continuously contract and release. This forces the urine down from the kidneys and to the bladder all day long. In fact, your ureters release urine into your bladder every 10 to 15 seconds.

Kidney

Your kidneys are the main organs in your urinary system and perform the most work. Located behind your abdomen, near the small of your back, these fist-sized bean-shaped organs have several important tasks. Although they aid in building strong bones and promoting red blood cell production, their main function is to remove the waste products and excess water from your blood through a filtering process. The kidneys then use the waste products and excess water to form urine. That urine is sent through the ureter to the bladder for storage.

References

• National Kidney and Urologic Diseases Information Clearinghouse: Your Urinary System and How It Works
• Image credit link to InfoVisual