The colon is located in the abdomen, connected to the esophagus and stomach above, and connected to the intestine below through the ileocecal valve. It is a key site for the digestion of food. The colon twists in the abdominal cavity, connected to the pyloric orifice of the stomach above and the cecum below, and is about 4-6 meters long, divided into three parts: duodenum, jejunum, and ileum. Digestion and absorption in the colon are particularly important, as the digestion process is basically completed after the food residues undergo chemical digestion by pancreatic juice, bile, and intestinal juice, and the reflexive digestion and absorption of colonic peristalsis, and nutrients are absorbed by the colonic mucosa.

The colon originates from the pyloric orifice of the stomach above and terminates at the ileocecal valve below, being the largest part of the digestive tract. In adults, it is about 5-7 meters long. According to its location and shape, it is divided into three parts: duodenum, jejunum, and ileum. It is a key site for the digestion and absorption of food. The colon tube narrows down gradually from the duodenum (about 3-5 cm) and the lumen of the terminal ileum is only 1.0-1.2 cm, making it easy for foreign objects to get stuck here.

Physiological function

The anatomical characteristics of the colon have created excellent standards for its digestion and absorption. The physiological functions of the colon are mainly manifested in the aspects of colonic peristalsis, metabolism, digestion and absorption, and so on, and are closely related to drug metabolism. For example, the various types of movements of the colonic smooth muscle can carry out mechanical digestion and absorption of food residues, such as grinding, mixing, and blending. The colonic mucosal metabolism, together with intestinal juice and bile in the colon, carry out the chemical digestion and absorption of food residues. The colonic mucosal metabolism contains a large number of endocrine cells, which can metabolize various digestive system growth hormones, such as cholecystokinin, somatostatin, gastric inhibitory peptide, and motilin, which have a key buffering effect on gastrointestinal peristalsis and metabolism.

Nutritional components and metabolism

The digestion and absorption of food residues begin in the colon, where the digestive and absorptive processes are primarily carried out due to the chemical digestion effects of pancreatic juice, intestinal juice, and bile, as well as the reflexive digestion and absorption effects of colonic peristalsis. The majority of nutrients that have undergone digestion and absorption are also absorbed in the colon, making the colon the most important site for digestion.