<prompt> Most common site of peptic ulcer in duodenum ?Pt pa2nd pa3rd pa41h pa  <response>: Ans. is a i.e., lst pa Peptic ulcer Ulcers are defined histologically as a breach in the mucosa of the alimentry tract that extends through the mucularis mucasea into the submucosa or deep. Peptic ulcers are chronic , most often solitary lesions that occur in any protion of the gastrointestinal tract exposed to the aggressive action of acid peptic juice . Peptic ulcers located in the following sits, in order of decreasing frequency : Duodenum, lspoion Stomach ,usally antrum At the gastro - esophageal junction in the setting of gastroesphageal reflux or Barretts esophagus. Within the margins of a gastrojejunostomy. In the duodenum, stomach or jeunum of patients with Zollinger -Ellison Syndrome. Within or adiacent to Meckels diveiculum that contains ectopic gastric mucosa. 