The Bowman's capsule filters blood to form urine. This primary urine has a lot of useful substances and passes into the proximal convoluted tubule (PCT). In the PCT, a lot of useful substances like glucose, salts, etc., are reabsorbed. Now, the urine enters the loop of Henle and then the distal convoluted tubule (DCT). Reabsorption of useful substances and secretion of unwanted substances take place here. Finally, the urine collects in the collecting duct where, concentration of urine by reabsorption of water takes place.