Answer
The alkaline fluid secreted by Brunner's glands (in the proximal duodenum) performs several functions. The most important is to neutralize the acid gastric juice and protect the mucosa of the duodenum from chemical damage.
Work Step by Step
The chyme that enters the duodenum from the stomach has a pH close to 2.0. This is a very acidic substance that could damage the mucosa of the small intestine. The alkaline secretion of Brunner's glands neutralizes chyme, and thus protects the mucosa of the small intestine from damage. There are other functions of these submucosal duodenal glands; they facilitate the action of the enzymes of pancreatic juice. They are also bacteriocidal and they provide some immunological defence.
