The principal function of the stomach is secretory and digestion thanks to the capacity of store, process and empties of food to the bowel. The acid secretion needs of complex neural functions, endocrines, autocrine y paracrine that act like a hole. The use of proton pump inhibitors is every day more frequent and over the counter, and requires the knowledge of the normal gastric physiology and the mechanism of inhibition for a rational use in clinical practice.