colon

Eva Rudolf-Müller is a freelance writer in the medical team. She studied human medicine and newspaper sciences and has repeatedly worked in both areas - as a doctor in the clinic, as a reviewer, and as a medical journalist for various specialist journals. She is currently working in online journalism, where a wide range of medicine is offered to everyone.

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The intestine is the part of the digestive tract in which the ingested food - after it has been crushed and digested in the mouth and stomach - is further digested. The small building blocks of nutrients (such as simple sugars, fatty acids, amino acids) are absorbed into the blood. Substances that cannot be used are excreted as stool (feces). Read everything you need to know about the intestine: anatomy, function and major diseases!

What is the intestine?

The intestine is the main part of the digestive system. It begins at the pylorus (stomach gatekeeper), leads to the anus (anus) and is divided into the slimmer small and the wider large intestine. Both in turn have several sections.

Small intestine

It is divided from top to bottom into the duodenum, the jejunum and the ileum. Read more about this in the article on the small intestine.

Colon

It is divided from top to bottom into the sections appendix (with appendix), colon (colon) and rectum or rectum (rectum with anus). Read more about it in the Colon article.

How long is the intestine in total?

The entire length of the intestine is about eight meters. Of this, five to six meters go to the small intestine and the rest to the large intestine.

What is the function of the intestine?

The meter-long digestive tract not only ensures the chemical breakdown of food, the absorption of the food components into the body (absorption) and the excretion of food residues via the anus. It also produces hormones (the digestive system is the body's largest hormonal gland). It also represents a barrier for pathogens and plays an important role in regulating the water balance: it can absorb and excrete large amounts of fluid.

Small intestine function

The large digestive glands flow into the duodenum: the liver, whose secretion (called bile) can be temporarily stored in the gallbladder, and the pancreas. Both digestive secretions contain important digestive enzymes for the chemical breakdown of carbohydrates, fats and proteins.

Additional glandular secretions, which come from the intestinal wall itself, participate in digestion. After the food has been chopped up and digested in the mouth and stomach, all food components in the entire small intestine are broken down into small components and absorbed (resorbed) into the blood:

Carbohydrates are broken down into simple sugars (monosaccharides), proteins are broken down into the individual amino acids, and fats are broken down into glycerine and free fatty acids. After being absorbed into the blood, the nutrients are first transported to the liver, the central metabolic organ, via the portal vein.

Other substances are also absorbed into the body in this way, such as vitamins and minerals.

Colon function

The food components that the body does not need and cannot use get into the large intestine. The muscle wall pushes this pulp with wave-like (peristaltic) movements through the individual sections to the exit (anus). On its way, the stool (feces) is thickened by dehydration. Secreted mucus makes it slippery.

Countless bacteria of more than 400 different species naturally live in the colon. Their total number is estimated at ten trillion, their total weight about 1.5 kilos. They process the indigestible food residues. They also produce substances that the body can still use in part (some B vitamins, vitamin K).

The work of the intestinal bacteria also creates gases and substances that give the thickened food pulp color and smell. This no longer usable feces is ultimately transported to the outside via the anus. Depending on the type of food consumed, it takes 33 to 43 hours from ingesting food to defecating.

Where is the intestine located?

It almost fills the abdomen below the stomach. The duodenum is located in the upper abdomen directly below the stomach, the jejunum joins at the top left and the ileum at the bottom right. The numerous loops of the jejunum and ileum are collectively referred to as a bundle. It is, so to speak, framed by the colon. This then flows outwards with the rectum and anus at the bottom.

What problems can the intestine cause?

In the case of a duodenal ulcer (ulcus duodeni), a more or less large area of ​​the mucous membrane in the duodenum is damaged. Often there is also an ulcer in the stomach (ulcus ventriculi). Men are affected more frequently than women. The cause of the ulcer is in most cases an infection with the "stomach germ" Helicobacter pylori.

Irritable bowel syndrome (Colon irritabile) manifests itself in chronic complaints such as diarrhea or constipation, flatulence and abdominal pain. An organic cause for this cannot be determined. The disease mainly affects women.

"Gastrointestinal flu" is an inflammation of the lining of the digestive tract caused by pathogens, which can lead to vomiting and diarrhea.

Crohn's disease and ulcerative colitis are chronic inflammatory bowel diseases (IBD). Crohn's disease can affect the entire digestive tract (from the oral cavity to the anus). The inflammatory process in ulcerative colitis usually begins in the rectum and spreads to the colon.

In people who suffer from hemorrhoids, a vascular cushion in the anal canal is pathologically enlarged. Possible symptoms are, for example, bright red traces of blood on the stool or toilet paper, pressure pain, burning or itching in the anus. In advanced stages, the stool can no longer be held back. Risk factors for hemorrhoids are, for example, repeated strong pressing during bowel movements, a low-fiber diet, pregnancy and weak connective tissue.

Diverticula are protrusions of the intestinal wall outward. If several diverticula form next to each other, doctors call this diverticulosis. The protrusions can become inflamed (diverticulitis). Sometimes they can burst too. The inflammation can then spread to the peritoneum. Diverticulitis is treated with antibiotics. Sometimes the inflamed diverticula also have to be surgically removed.

Intestinal polyps are protrusions of the mucous membrane that form mainly in the colon and rectum - usually without any identifiable cause. They often do not cause any symptoms, but should still be removed because they can degenerate and lead to colon cancer.

This very common cancer is the second most common form of cancer among women and the third most common form of cancer among men in Germany. In most cases, the malignant tumor in the intestine affects the last two sections of the intestine: colon (colon carcinoma) or rectum (rectal carcinoma).

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