The kidney plays a major role in the excretory system of our body. It filters out the toxic waste from our blood and drains it in the form of urine. The functional unit of the kidney is Nephron . In each kidney, approximately 1million nephrons are present. The structure of a nephron is a little complex. The Glowmerulus, PCT, DCT and the collecting duct together constitute the nephron. Each part have a different function. One filters the blood, another maintains the concentration of urine, while the other returns useful minerals back to the blood.