Ulcers 

During normal digestion, food moves from the mouth down the esophagus into the stomach. The stomach produces hydrochloric acid and an enzyme called pepsin to digest the food. From the stomach, food passes into the upper part of the small intestine, called the duodenum, where digestion and nutrient absorption continue.

An ulcer is a sore or lesion that forms in the lining of the stomach or duodenum where acid and pepsin are present. Ulcers in the stomach are called gastric or stomach ulcers. Those in the duodenum are called duodenal ulcers. In general, ulcers in the stomach and duodenum are referred to as peptic ulcers. Ulcers rarely occur in the esophagus or in the first portion of the duodenum, the duodenal bulb.

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