secrete large amounts of alkaline mucus in response to (1) tactile or irritating stimuli on the duodenal mucosa; (2) vagal stimulation, which increases Brunner's glands secretion concurrently with increase in stomach secretion; and (3) gastrointestinal hormones, especially secretin.

Its function is to complete the process begun by pancreatic juice; the enzyme trypsin exists in pancreatic juice in