Hydrochloric acid
Gastric acid also known as "gastric juice" is secreted from gastric glands, which are located in narrow tube like structures called gastric pits. Gastric juice contains hydrochloric acid, pepsinogen and mucus in a healthy adult. Hydrochloric acid is secreted by parietal cells, pepsinogen is secreted by gastric chief cells and mucus is secreted by mucus neck cells.