The blood is filtered in the Bowman's capsule by ultrafilteration. The filterate contains a lot of useful substances along with the waste materials. All these useful substances have to be reabsorbed. The filterate passes through the proximal convoluted tubule (PCT) from the Bowman's capsule. Then into the Henle's loop, distal convoluted tubule (DCT) and finally into the collecting duct. As the filterate passes through this, the required substances are reabsorbed.