What is the function of the large intestine

Structure and function of the small and large intestines

The Intestines is made up of the small intestine and large intestine.

Small intestine. The main place for digestion and absorption of the food components in the blood is Small intestine, which is connected to the posterior abdominal wall by connective tissue hanging straps. In order to be able to absorb the usable food components, the wall of the small intestine is strongly folded up. Intestinal folds and villi increase its absorption surface to around 200 m2.

The duodenum close to the first section of the small intestine Jejunum(Jejunum) and the Ileum(Ileum). Peristaltic movements of the small intestine wall push the intestinal contents further and further towards the large intestine. On the entire way through the digestive tract, liquid is repeatedly added to the chyme, which is then withdrawn from it in the large intestine.

Colon. The one about 1.5 m long Colon consists of the appendix(Caecum, Zökum) with Appendix(Appendix vermiformis) and the Colon, which makes up the majority of the colon. The colon is divided into an ascending colon (ascending colon), a transverse colon (transverse colon, transverse colon), a descending colon (descending colon) and an S-shaped curved sigmoid colon (sigmoid colon or sigmoid). This passes into the last part of the intestine, the rectum or rectum, without any clear separation.

Small and large intestines are in the area of ​​the appendix by the Ileocecal valve (Bauhin's valve), which is located between the ileum and the appendix and, like a non-return valve, prevents the colon contents containing bacteria from flowing back into the small intestine. The large intestine no longer digests anything - its job is to remove water and salts from the remaining digestive pulp. In this way, the intestinal contents are thickened from initially 1,500 ml of chyme to 200 ml of stool per day.

The large intestine begins in the right lower abdomen, where the small intestine joins the appendix with the appendix. From there it runs like a frame up the side wall of the fuselage, pulls in a garland to the left and down the left wall of the fuselage again. The conclusion is the S-shaped sigmoid colon, which merges into the rectum.
Georg Thieme Verlag, Stuttgart

Intestinal flora.The intestine is colonized by up to 400 different types of bacteria and other microorganisms, which together form the intestinal flora. The highest bacterial density is found in the large intestine and in the rectum. A healthy intestinal flora protects the intestinal mucosa from the colonization of pathological germs. She is involved in the production of the body's own vitamins, such as B. Vitamin K, participates and breaks down indigestible food components (e.g. dietary fiber) that cannot be broken down by the digestive enzymes and therefore reach the large intestine unchanged. In addition, the intestinal-specific immune system is trained by the constant contact of the intestinal flora with the immune cells in the intestine, which at the same time activates the body's defenses.

The composition of the intestinal flora changes due to diseases and antibiotics. But probiotic bacteria (probiotics) taken as food supplements can also cause temporary changes in the stool.

The highly specialized defense system of the intestinal mucosa is only partially understood to this day. It is essential for survival so that the billions of pathogens and allergens that get into the intestine do not cause any damage. Therefore it apparently works at the time of birth (innate immunity) and also forms a kind of endogenous antibiotic, the defensins.


Dr. med. Arne Schäffler, Dr. Bernadette Andre-Wallis in: Health Today, edited by Dr. med. Arne Schäffler. Trias, Stuttgart, 3rd edition (2014). Revision and update: Dr. med. Sonja Kempinski | last changed on at 16:24