STRUCTURE AND FUNCTIONS OF KIDNEY There are two kidneys in body , Rt & Lt, lying on post abdominal wall, outside peritoneal cavity. There weight is aprx. 150 Gm and size is clenched fist. On medial side, there is a region called hilum through which pass blood & lymphatic vessels, nerve fibers and ureterKidney is surrounded by a protective fibrous capsule. Each kidney has two major zones, outer thick known as cortex and part known as medulla. Medulla is divided into multiple cone shaped tissue masses called renal pyramid. The base of pyramid begins at junction of cortex & medulla and terminates in papilla which projects into space of renal pelvis. Renal pelvis is funnel shaped continuation of upper end of ureter. 1- Excretion of metabolic waste products such as urea, creatinine, uric acid, Bilirubin, hormones & drugs. 2-. ELIMINATE HARMFUL FOREIGN COMPOUNDS. Such as toxins, drugs, heavy metals, pesticides. 3- Regulation of water & electrolyte balance to maintain normal homeostasis of body by re-absorption and adjustment of rate of excretion of various substances. 4- Regulation of Arterial Pressure. *Long term regulation by excreting variable amounts of water and sodium and *short term by secreting vaso-active substance (renin).