Final answer:
Brunner's glands in the submucosa of the small intestine produce bicarbonate-rich alkaline mucus, which helps neutralize acidic chyme. Alongside these, crypts of Lieberkühn produce intestinal juice for digestion and nutrient absorption.
Step-by-step explanation:
The structures that produce mucus and are found in the submucosa of the small intestine are known as Brunner's glands or duodenal glands. These glands secrete a bicarbonate-rich alkaline mucus which plays a crucial role in neutralizing the acidic chyme as it moves from the stomach into the duodenum, the first section of the small intestine. The mucus serves as protection for the intestinal wall and also assists in the digestive process.
Beyond the Brunner's glands, the small intestine also contains numerous crypts of Lieberkühn which are indentations in the mucosa housing intestinal glands. These glands produce intestinal juice, a mixture of water and mucus, aiding in the digestion and absorption of nutrients. Overall, the presence of mucus in the digestive tract is essential for both protecting the lining and facilitating the movement of digested materials.