The majority of digestion and absorption occurs in the small intestine. This is a narrow tube measuring 20 feet long, divided into three parts including the duodenum, the jejunum and the ileum. Enzymes secreted in the small intestine break down the chyme from the stomach and absorb the nutrients.
Chyme from the stomach enters the C-shaped duodenum, where the intestinal wall secretes bile, pancreatic juice and other enzymes. These fluids neutralize stomach acids and break down fats, oils, proteins and carbohydrates. The nutrients and byproducts go to the coiled jejunum for absorption, and any remaining products go to the ileum for excretion.