Your two kidneys are vital organs that perform many functions to keep your blood clean and chemically balanced. Understanding how your kidneys work can help you to keep them healthy.
What are the kidneys and what do they do?
The kidneys are bean-shaped organs, each about the size of a fist. They are located just below the rib cage, one on each side of the spine. Every day, the two kidneys filter about 120 to 150 quarts of blood to produce about 1 to 2 quarts of urine, composed of wastes and extra fluid. The urine flows from the kidneys to the bladder through two thin tubes of muscles called ureters, one on each side of the bladder. The bladder stores urine. The muscles of the bladder wall remain relaxed while the bladder fills with urine. As the bladder fills to capacity, signals sent to the brain tell a person to find a toilet soon. When the bladder empties, urine flows out of the body through a tube called the urethra, located at the bottom of the bladder. In men the urethra is long, while in women it is short.
Why are the kidneys important?
The kidneys are important because they keep the composition, or makeup, of the blood stable, which lets the body function. They:
- prevent the buildup of wastes and extra fluid in the body
- keep levels of electrolytes stable, such as sodium, potassium, and phosphate
- make hormones that help
- regulate blood pressure
- make red blood cells
- bones stay strong
How do the kidneys work?
The kidney is not one large filter. Each kidney is made up of about a million filtering units called nephrons. Each nephron filters a small amount of blood. The nephron includes a filter, called the glomerulus, and a tubule. The nephrons work through a two-step process. The glomerulus lets fluid and waste products pass through it; however, it prevents blood cells and large molecules, mostly proteins, from passing. The filtered fluid then passes through the tubule, which sends needed minerals back to the bloodstream and removes wastes. The final product becomes urine.
For More Information:
American Kidney Fund
11921 Rockville Pike, Suite 300
Rockville, MD 20852
c/o Medical Education Institute, Inc.
414 D'Onofrio Drive, Suite 200
Madison, WI 53719
National Kidney Foundation
30 East 33rd Street
New York, NY 10016
Phone: 1-800-622-9010 or 212-889-2210