<prompt> In the stomach, H ions are secreted in exchgHjjii forNaKGarCT  <response>: H ions are generated inside parietal cells from metabolic CO2 H2O present in cell in the presence of enzyme carbonic anhydrase. -The enzyme accelerates the formation of H2CO3 which dissociates to release H HCO3-. -The H ions generated are then secreted into the lumen of the canaliculi in exchange for K by a primary active transpo mediated by a H-K-AT Pase pump. Ref: Medical Physiology, Indu Khurana 