Gastrointestinal structure of human body

The human digestive system consists of digestive tract and digestive glands.

The human digestive tract includes mouth, pharynx, esophagus, stomach, small intestine (including duodenum, jejunum and ileum) and large intestine (including cecum, appendix, colon and rectum).

Clinically, the upper digestive tract is often divided into upper digestive tract (above duodenum) and lower digestive tract (below duodenum).

Digestive glands include salivary glands, stomach glands, liver, pancreas and intestinal glands. Its main function is to secrete digestive juice and participate in digestion.

Extended data

The basic physiological function of the digestive system is to ingest, transport, digest food, absorb nutrients and excrete waste. The completion of these physiology is beneficial to the coordinated physiological activities of the whole gastrointestinal tract.

The digestion and absorption of food provide the substance and energy needed by the body. In addition to vitamins, water and inorganic salts, nutrients in food can be directly absorbed and utilized, while protein, fat and sugar cannot be directly absorbed and utilized by human body.

It needs to be decomposed into small molecular substances with simple structure in the digestive tract before it can be absorbed and utilized.

The process that food is broken down into small molecules with simple structure and can be absorbed in the digestive tract is called digestion. The process of this small molecular substance entering the blood and lymph through the epithelial cells of the digestive tract is absorption.

For unabsorbed residues, the digestive tract is discharged in the form of feces through the large intestine.

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