First, the difference: there are small intestinal villi on the surface folds of the small intestine, and there are abundant capillaries in the small intestinal villi, which increases the contact area between the small intestine and food, while there are no villi on the large intestinal folds. There are intestinal glands in the inner wall of small intestine, which can secrete intestinal fluid, but there are no intestinal glands in the inner wall of large intestine.

2. Similarities: There are folds on the surface of small intestine and large intestine, all of which are over1.5m in length.

Third, the small intestine is located in the abdomen, with the upper end connected to the pylorus and the stomach, and the lower end connected to the large intestine through the orifice, which is the main place for food digestion and absorption. The small intestine is coiled in the abdominal cavity, connected with the stomach pylorus and cecum, with a total length of about 4-6 meters, and divided into three parts: duodenum, jejunum and ileum.

Digestion in small intestine is very important, because food is basically digested by chemical digestion of pancreatic juice, bile and small intestine fluid in small intestine and mechanical digestion of small intestine movement, and nutrients are absorbed by small intestine mucosa at the same time.

The large intestine, divided into cecum, appendix, colon, rectum and anal canal, is an organ that absorbs water from food residues, and food residues themselves form feces and are discharged to some extent. It is an important part of human digestive system and the lower segment of digestive tract.

The large intestine lives in the abdomen, with its upper mouth connected to the small intestine at the hilum and its lower end connected to the anus. The whole process is shaped like a box, surrounding the jejunum and ileum. The large intestine is obviously different from the small intestine in appearance. Generally, the large intestine has a larger caliber and a thinner wall.

Extended data:

1, physiological function of small intestine

The histological characteristics of small intestine create favorable conditions for its absorption. The physiological functions of small intestine show the movement, secretion, digestion and absorption of small intestine, and are closely related to drug metabolism.

For example, various forms of movement of small intestinal smooth muscle can complete the mechanical digestion of chyme, such as grinding, mixing and stirring. Small intestinal fluid secreted by small intestinal glands can complete the chemical digestion of chyme together with bile and pancreatic fluid in the small intestine. There are many endocrine cells scattered in the secretion of small intestinal mucosa, which can secrete a variety of digestive tract hormones, such as secretin, cholecystokinin, gastrin and motilin, which have important regulatory effects on gastrointestinal movement and secretion.

2. Physiological function of large intestine

(1) Main transmitted dregs: The large intestine receives the food residues transmitted from the small intestine, absorbs the excess water and forms feces. The movement of qi in the large intestine transports feces to the end of the large intestine and excretes them through the anus in a controlled way, so the large intestine is called "the official of preaching".

(2) The large intestine governs body fluid: the large intestine receives food residues containing a large amount of water from the small intestine, and absorbs the water from them to form feces, which is called drying. The large intestine absorbs water and participates in the metabolism of water and liquid in the body, so it is said that "the large intestine governs body fluid".

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