Even if it sounds strange: the digestion begins in the mouth. There, the enzymes contained in the saliva perform a rough preliminary work. Chew on wholemeal bread for a while - it suddenly tastes sweet, because enzymes break down the starch into sugar. The stomach later closes proteins with its acid and emulsifies fats. Through the "gatekeeper" the porridge passes from the stomach into the small intestine. The small intestine is divided into three parts: duodenum ("duodenum"), jejunum and ileum. On a total of about five meters, he winds his way through the abdomen. In the small intestine, the actual food intake and the utilization of the food components takes place. The individual parts - molecules such as glucose, fats or even vital minerals such as potassium and calcium - now enter the blood via the intestinal mucosa and can thus reach the entire organism.
Great surface of the intestine
To cope with this onslaught, nature has come up with something clever. The surface of the small intestine is thereby immensely enlarged, because the mucous membrane lies in so-called villi and wrinkles. Wrinkles are distinct elevations with a "connective tissue socket", villi are small finger-shaped mucosal protrusions.
In the duodenum, the ducts lead to the liver and pancreas, whose digestive juices unfold their effect in the small intestine. The bile acids of the liver are important for the digestion of fat, the various enzymes of the pancreas further close down proteins, as well as fats and carbohydrates.
The colon and rectum are the last sections of the digestive tract. In the large intestine, water and electrolytes are removed from the indigestible remnants of the porridge and returned to the body. In addition, bacteria colonize the colon, for example lactobacilli and Escherichia coli. The bacteria are essential for normal bowel activity, further reducing indigestible remnants and also producing essential vitamins for us.