Site of maximum bicarbonate absorption-: (A) Proximal convoluted tubule, (B) Distal convoluted tubule, (C) Cortical collecting duct, (D) Medullary collecting duct
Answer is A. Ans. is 'a' i.e., Proximal convoluted tubule o About 80-90 of filtered HCO3- is absorbed in PCT.o Absorption of HCO3- is indirect, which is due to secretion H+, i.e., secretion of H+ is coupled with absorption of HCO3o Filtered HCO3- reacts with H+ to form H2CO3 which then is dissociated into H2O and CO2.o CO2 diffuses into epithelial cell and generate HCO3- which is then reabsorbed.