Bay Area Medical Information (
Anatomy of the Urinary System




The Kidney

KidneyThe urinary system functions to create urine, store it, and carry it out of the body. It is made up of two kidneys, two ureters, the bladder, two sphincter muscles, and the urethra. Illustration adapted from drawing of kidney from the Nat'l Istitute of Diabetes and Digestive and Kidney Diseas, National Institute of Health

The kidneys are bean-shaped organs, each about the size of your fist. They are located near the middle of your back, just below the rib cage.

Kidneys remove wastes and extra water from the blood to form urine. About 2 quarts of urine is made each day from filtering about 200 quarts of blood through the kidneys. If your kidneys did not remove these wastes, the wastes would build up in the blood and you would eventually die. Some people have serious health problems if they have less than 25 percent of their renal function. If renal function drops below 10 to 15 percent, a person cannot live long without some form of renal replacement therapy—either dialysis or transplantation.

Urine flows from the kidneys, through the ureters, and empties into the bladder.   The urethral sphinctor (a valve that seals off the bladder outlet through the urethra)  remains closed, during this time, allowing the bladder to fill.Urinary tract 

The urinary bladder is composed of smooth muscle which is normally relaxed at rest.

The bladder first signals an urge to empty when it is about half full. 

Urination normally begins voluntarily, by muscle contraction, pushing the urine out of the bladder, causing the sphinctor to open. Once urination begins, the urine flows from the bladder, past the now open urethral spinctor, and out of the body through the urethra. 

Read More

Home| About Us | Advertise | Contact Us |Terms of Use | Privacy Policy
BAMI is an up-to-date educational source for patient education. Health care providers may feel free to print out copies for their patient's use. Please note that content may not be copied for resale or other commercial use such as for web sites. The content on this site is for informational purposes only and is not intended to be a substitute for professional medical advice, diagnosis, or treatment.   
Never disregard professional medical advice or delay in seeking it because of something you have read on this site. 
Display of an advertisement does not imply an endorsement of the product.

©2015 Bay Area Medical Information (™ All Rights Reserved
Google |  Yahoo |  MSN |  AOL |  Netscape |  Earthlink |  Dogpile |  All the Web |  AltaVista