Explain what causes the pain that occurs with astomach ulcer.

A stomach ulcer, also known as a gastric ulcer, is a sore that develops on the lining of the stomach. The primary cause of this condition is the bacterium Helicobacter pylori (H. pylori). Other factors that can contribute to the development of stomach ulcers include the long-term use of nonsteroidal anti-inflammatory drugs (NSAIDs) and an excess production of stomach acid.

Here's a step-by-step explanation of what causes the pain associated with a stomach ulcer:

1. Infection with H. pylori: This bacterium damages the mucous coating that protects the lining of the stomach and the upper part of the small intestine (duodenum). Without this protective coating, acid can erode the lining of the stomach, leading to an ulcer.

2. Use of NSAIDs: These drugs, which include common pain relievers like ibuprofen, can also break down the mucous layer that protects the stomach lining. This allows acid to get through to the sensitive lining beneath. Both the acid and the bacteria can irritate the lining and cause a sore, or ulcer, to form.

3. Excess stomach acid: While not typically a primary cause of ulcers, having too much stomach acid can make existing ulcers worse and more painful. This is because the acid further erodes the lining of the stomach where the ulcer has formed.

The pain associated with a stomach ulcer is caused by the ulcer itself and the acid in the stomach coming into contact with the ulcer. This can cause a burning or gnawing pain in the middle or upper stomach between meals or at night. The pain can last from a few minutes to a few hours and can be relieved by eating certain foods that buffer stomach acid or by taking acid-reducing medications.