Chapter 3 The Digestive System 113 Anorexia nervosa is characterized by an extreme aversion to food that results in weight loss and may lead to malnutrition (Figure 3.6). Bulimia nervosa involves repeated gorging of food followed by intentional vomiting and/or laxative abuse. Severe eating disorders can be life-threatening. Ulcers An ulcer, or peptic ulcer, is a breakdown in the mucosal lining of the esophagus, stom- ach, or duodenum caused by chronic irrita- tion (Figure 3.7). This breakdown is caused by hydrochloric acid and pepsin, the acidic chemicals involved in the digestion of food. Esophageal, gastric, and duodenal ulcers are types of peptic ulcers. Most ulcers are caused by Helicobacter pylori (H. pylori), a bacterium that attacks the weak- ened mucosa. Dyspepsia (epigastric pain with bloating and nausea) is a common symptom. Factors that may contribute to ulcer formation include stress, excessive caffeine consumption, Hubert Raguet / Science Source Figure 3.6 Distorted body image is a major symptom of anorexia nervosa. Esophagus Duodenum Stomach Ulcer Ulcer Ulcer Mucosa Submucosa Muscle Figure 3.7 A peptic ulcer is a breakdown in the mucosal lining of the stomach or duodenum. It is caused by chronic irritation from highly acidic gastric chemicals.