Principle objective of this lecture is to present on the kidney. The kidneys are two 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 kidneys’ function are to filter the blood. All the blood in our bodies passes through the kidneys several times a day. The kidneys remove wastes, control the body’s fluid balance, and regulate the balance of electrolytes.