Most people have two kidneys, located on either side of the spine, just below the rib cage. The kidneys maintain the proper chemical balance in the body. They filter out waste products and extra fluid and eliminate them from the body through the urine. The kidneys also help control blood pressure and the production of red blood cells. The process of filtering the bodies wastes and preparing urine is detailed in the pictures and captions below.
Blood is pumped from the heart through large blood vessels to the kidneys.
There, the blood vessels continue to divide until they become so small that they can no longer hold water. The tiny vessels turn into filters called glomeruli. The filtered blood is returned to the body through the veins, and the water passes through tubules where it is recycled, and is eliminated as urine. Together, they filter the blood, process the filtrate and make urine. When something goes wrong in the kidneys, kidney disease occurs.