Pathogenesis of reflux esophagitis and Barrett's esophagus.

An understanding of the pathogenesis of reflux esophagitis and Barrett's esophagus requires knowledge of the noxious elements in gastric juice and the three major esophageal defenses designed to protect against them. When the esophageal epithelium cannot prevent gastric acid from acidifying the intercellular spaces, the foundation is set for the development of the major symptoms, signs, and complications of reflux esophagitis. Inadequate defense by the epithelium can occur by exposure to the acidic refluxate for a prolonged period of time, because of defects in the antireflux or luminal clearance mechanisms, or by exposure to ingested products that directly impair the epithelium's intrinsic defenses, rendering it vulnerable to injury from even physiologic levels of acid reflux.