From the Bowman's capsule, the glomerular filtrate enters the proximal convoluted tubule (PCT). PCT is surrounded by a network of peritubular capillaries and is the seat of reabsorption. About $75 \%$ of glomerular filtrate is normally reabsorbed in PCT before reaching the loop of Henle. The reabsorbed materials include glucose, amino acids, vitamins, hormones, sodium, potassium, chlorides, phosphates, bicarbonates, most of water and some urea etc.