Sophisticated reprocessing machines, the kidneys are bean-shaped organs, each about the size of a fist, located near the middle of the back, just below the rib cage. Everyday, the kidneys play a major part in maintaining the body’s internal environment, processing about 200 quarts of waste products and extra water, which are excreted as urine.
The kidneys:
monitor blood volume
filter the blood and form urine
regulate water, electrolyte and acid base balance
produce and metabolize some hormones
balance the amount of calcium, sodium and potassium present in blood
produce hormones that regulate blood pressure
stimulate the production of energy-rich red blood cells
At rest, an estimated 20% of blood output from the heart flows through the kidneys where it is filtered and reconditioned.
When the kidney's fail, it is known as renal failure.