The small intestine is the main place for food digestion and absorption.
The small intestine is the longest in the whole digestive tract, and its organizational and structural characteristics determine the absorption function of the small intestine. There are many glandular cells in the mucous layer of the small intestine, which can secrete a variety of digestive tract hormones, such as gastric inhibitory peptide, gastric motility, pancreatic stimulating hormone, cholecystokinin and so on, which play an important role in regulating the gastrointestinal motility.
After chewing by the teeth and grinding, mixing and stirring in the stomach, the food has been transformed into coeliac, which is initially digested in the stomach and then enters the small intestine to complete the digestion and absorption of most of the nutrients.
Coeliac in the small intestine stays the longest, the digestive fluid secreted in the lumen of the small intestine and the bile and pancreatic juice discharged into the small intestine together complete the digestion and decomposition of food, the distribution of capillary network on the mucosal surface of the small intestine is very well developed, and the nutrients such as glucose, amino acids, lipid molecules and other nutrients after the decomposition of food are absorbed into the bloodstream through the capillary network.