The gastrointestinal tract in humans consists of different sections. The first part of the small intestine, which connects to the stomach, is called the duodenum.
What is the duodenum?
Infographic showing the anatomy and location of a duodenal ulcer. Click image to enlarge. Each adult human has an intestinal tract with an average length of about seven to eight meters, with the small intestine accounting for the largest portion at six meters. The first section of the small intestine is called the duodenum. The reason for this is its average length of about 30 cm, which corresponds to the length of twelve fingers placed end to end. Furthermore, the duodenum is the most proximal part of the small intestine, that is, the part closest to the center of the body.
Anatomy and structure
From an anatomical point of view, the duodenum begins from the pylorus, also called the gatekeeper of the stomach. At its other end, in turn, begins the second section of the small intestine, called the jejunum or empty intestine. This leads on to the third section of the small intestine, the ileum. Unlike the beginning of the duodenum, the other transitions to the other parts of the intestine are fluid, that is, there are no sharp demarcations. The duodenum in humans is shaped like a “C”. This is different in herbivorous animals. Here the duodenum has the shape of a horseshoe. The reason is that the food usually eaten by humans is much more stable in consistency than that of herbivorous animals. For example, cooked pieces of meat are not already completely decomposed in the stomach, so that even coarser components have to pass through the duodenum on their way to the small and large intestines. This is why the human duodenum is designed for coarser foods. The duodenum is further fused to the abdominal cavity by its back wall so that it does not change position as part of natural intestinal movements. This is important to the extent that the C-shape might not be maintained. Internally, the surface of the duodenum is greatly enlarged. This serves the purpose of absorbing as many vitamins and nutrients as possible.
Functions and tasks
In order for the food pulp pre-digested in the stomach to be utilized in the small and large intestines, the duodenum is of vital importance. This is because its main function is to pass enzymes produced in the pancreas and gallbladder into the intestine. Without enzymes, the other sections of the small intestine would not be able to further digest the food pulp and filter out the necessary minerals and nutrients. For this purpose, the duodenum is connected to the gallbladder as well as to the pancreas. In order to prevent the acidic PH of the incoming enzymes from damaging the inner wall of the intestine too much, the PH is largely neutralized while still in the duodenum by various alkaline secretions. To ensure that the enzymes can also mix with the food pulp, the duodenum has a natural motility mechanism, albeit less pronounced than the possibilities of the other intestinal sections. While the motility mechanism of the duodenum is conducive to mixing the enzymes with the food pulp, the motility mechanism of the other intestinal segments serves the purpose of keeping the food pulp moving forward and preventing constipation from setting in. Moreover, the duodenum has the same mucous membrane of the other intestinal segments. This means that it is just as capable of extracting vitamins and minerals from the food pulp. Only minerals and water it cannot absorb; this task is the exclusive responsibility of the penultimate section of the intestine: the colon.
Diseases
Precisely because of the fact that pathogens that have entered through food also pass through the duodenum, the risk of possible disease of this section of the intestine is particularly high. The most common of these is duodenal ulcer. The bacterium Helicobacter pylori is the regular trigger of this disease, which affects about two percent of all Germans at some point in their lives. Typical symptoms include sudden weight loss, bloating, abdominal pain and irregular bowel movements.Acute and chronic inflammation of the duodenum is also relatively common, the cause of which is again often infection with various bacteria, such as salmonella and shigella. In contrast, the incidence of duodenal carcinoma is rarer. This type of cancer occurs mainly in patients with Crohn’s disease. Because their small intestines have chronic inflammatory changes, the risk that the duodenal mucosa will eventually form tumor cells is higher than in healthy people.
Typical and common intestinal diseases
- Duodenal ulcer
