Final answer:
Duodenal (Brunner's) glands secrete mucus and bicarbonate to neutralize the acidic chyme in the duodenum.
Step-by-step explanation:
The function of duodenal (Brunner's) glands in the duodenum is to secrete mucus and bicarbonate. These glands are found in the submucosa of the duodenum and produce a bicarbonate-rich alkaline mucus that helps to neutralize the highly acidic chyme that enters the duodenum from the stomach. This function is important for the proper digestion and absorption of nutrients in the small intestine.