The small intestine is specialized for digestive and absorptive functions. It receives the acidic chyme from the stomach. Digestion requires a neutral pH that is achieved by secretions from Brunner's glands and the exocrine pancreas.
The small intestine is divided into three regions:
Duodenum - proximal portion adjacent to the stomach.
Villi - tall, slender finger-like projections that extend into the lumen.
Brunner's Glands - only region of the gastrointestinal tract (along with the esophagus) with glands in the submucosa.