More than 6 million people in the United States have a peptic ulcer -- an open sore or raw area that tends to develop in one of two places:
- The lining of the stomach (gastric ulcer)
- The upper part of the small intestine -- the duodenum (duodenal ulcer)
In the U.S., duodenal ulcers are three times more common than gastric ulcers.
Ulcers average between one-quarter and one-half inch in diameter. They develop when digestive juices produced in the stomach, intestines, and digestive glands damage the lining of the stomach or duodenum.
The two important components of digestive juices are hydrochloric acid and the enzyme pepsin. Both substances are critical in the breakdown and digestion of starches, fats, and proteins in food. They play different roles in ulcers:
- Hydrochloric acid. A common misperception is that excess hydrochloric acid, which is secreted in the stomach, is solely responsible for producing ulcers. Patients with duodenal ulcers do tend to have higher-than-normal levels of hydrochloric acid, but most patients with gastric ulcers have normal or lower-than-normal acid levels. Some stomach acid is actually important for protecting against H. pylori, the bacteria that cause most peptic ulcers. [Note: An exception is ulcers that occur in Zollinger-Ellison syndrome, a rare genetic condition in which tumors in the pancreas or duodenum secrete very high levels of gastrin, the hormone that stimulates the release of hydrochloric acid.]
- Pepsin. Pepsin, an enzyme that breaks down proteins in food, is also an important factor in the formation of ulcers. Because the stomach and duodenum are composed of protein, they are susceptible to the actions of pepsin.
|Click the icon to see an image of the stomach.|
Fortunately, the body has a defense system to protect the stomach and intestines against these two powerful substances:
- The mucus layer, which coats the stomach and duodenum, forms the first line of defense.
- Bicarbonate, which the mucus layer secretes, neutralizes digestive acids.
- Hormone-like substances called prostaglandins help widen the blood vessels in the stomach, to ensure good blood flow and protect against injury. Prostaglandins are also believed to stimulate bicarbonate and mucus production.
Disrupting any of these defense mechanisms makes the lining of the stomach and intestine susceptible to the actions of acid and pepsin, increasing the risk for ulcers.
Review Date: 07/18/2011
Reviewed By: Reviewed by: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.