Ulcers are wounds in the stomach that are similar to small cuts or tears. These wounds can harm the tissue(生物组织) in the stomach, the pipe that carries the food to the stomach or parts of the small intestines(肠)。 Fluids( 液体) in the stomach then increase the pain of an ulcer. How does aperson know he or she has an ulcer? Doctors say most people with ulcers feel a burning pain intheir chest or stomach. This pain often is called heart-burn. It usually happens before eating orduring the night. It causes some people to lose their desire to eat, or they are unable to keep food in their stomachs.