The kidney is an important part of the body system. Kidneys remove wastes and extra fluid from the body, remove acid that is produced by the cells of the body and maintain a healthy balance of water, salt, and minerals, such as sodium, calcium, phosphorus, and potassium in the blood. The kidney cleanses the blood of toxins and transforms the waste into urine. The kidneys carry out a number of highly integrated functions that include maintenance of body fluid, electrolytes and acid-base balance, regulation of blood pressure via orchestrated changes in sodium balance and the synthesis and secretion of renin.