stomach acid

Gastric juices secreted by specialized cells lining pits in the wall of the stomach. Gastric juice contains an enzyme called pepsin that digests protein. It also contains hydrochloric acid and water. The hydrochloric acid is very strong and is needed to help kill bacteria that may cause illness and provides acid conditions in which pepsin works quickly.

On a scale of acidity called the pH scale, the acid secretions from the stomach wall are between pH 0.8 and pH 1.0. This makes the secretions so strong that, if bottled, they would be too dangerous to have on an open shelf in a school laboratory and would have to be labelled ‘corrosive’. This is strong enough normally to destroy human tissues on contact. The stomach is protected against damage from the acid by a lining of mucus, unless a person suffers from an ulcer.