Welcome to the ProGReSS AKI Study
The Kidneys and How They Work

The kidneys are two bean-shaped organs, each about the size of a fist (Figure 1). They are located near the middle of the back, just below the rib cage. Inside each kidney about a million tiny structures called nephrons filter blood (Figure 2). Each nephron contains several capillary blood vessels (glomerulus) and tiny tubules that lead to larger collecting ducts. The glomeruli filter fluid from the blood and extract both waste products and other substances such as sodium, phosphorus and potassium. Sodium, phosphorus and potassium are needed by the body and are reabsorbed into the bloodstream. The remaining waste is excreted in urine through the tubules that lead into the ureters and then into the bladder. Damage to the nephrons result in kidney disease. This damage may leave kidneys unable to remove waste or control body fluid.

Figure 1

Figure 2