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The duodenum is a part of the digestive tract that is the beginning of the small intestine. The duodenum is just behind the stomach. The main task of the duodenum is to digest food and absorb nutrients. Disease processes within the duodenum can cause epigastric pain. Find out how the duodenum is built, what is the role of the duodenum in food digestion and what is the diagnosis and treatment of duodenal diseases.
The duodenumis the initial fragment of the small intestine, located between the stomach and jejunum. The length of the duodenum is 25-35 cm on average, and has historically been referred to as the length of "twelve fingers". Within the duodenum there are 4 parts: the bulb (directly adjacent to the stomach) and the descending, horizontal and ascending parts. The entire duodenum resembles a C-shaped tube.
Duodenum - structure
To be able to perform its function well, the duodenum is located in close proximity to the digestive glands: the pancreas and the liver. Connections with these organs enable the transport of digestive enzymes into the lumen of the duodenum.
In the anatomy of the duodenum, the so-called Vater's wart. It is the place where the bile and pancreatic ducts open to the duodenum. Through the Vater's nipple, bile and pancreatic juice enter the duodenum, which allow food to be digested.
The duodenum is entwined with a dense network of blood vessels - pancreatic-duodenal arteries and veins. As the food content moves to the duodenum, blood flows to the surrounding vessels. As a result, nutrients formed during the digestion of food can quickly enter the bloodstream.
The end of the duodenum is connected to the jejunum. At this junction, the duodenum is attached to the abdominal wall with the so-called Treitz ligaments. The Treitz ligament is an important orientation structure for surgeons - it forms the border between the upper and lower gastrointestinal tract.
In terms of microscopy, the duodenal wall consists of 3 layers: mucosa, submucosa and muscle. The duodenal mucosa, as in other parts of the small intestine, is richly folded.
This way it creates the so-called intestinal villi that allow you to increase the areaabsorption of nutrients. Additionally, Bruner's glands are present in the duodenal wall, which are not found in other parts of the gastrointestinal tract. Their task is to produce an alkaline secretion that neutralizes the reaction of the chyme mixed with acidic gastric juice.
Duodenum - Features
The duodenum, like the rest of the small intestine, allows you to absorb nutrients from the food you eat. Before these substances enter our bloodstream, they must be broken down into small-molecule chemicals. The transformation into small molecule compounds is the essence of the digestive process.
The duodenum is mainly digested of two groups of nutrients: carbohydrates and fats. The digestion process takes place with the participation of enzymes, i.e. compounds that enable chemical reactions to occur.
The most important enzymes in the duodenum are amylase and lipase, which are involved in the digestion of carbohydrates and fats, respectively. These enzymes are produced in the pancreas and then transported through the pancreatic ducts to the duodenum.
Another substance that plays a huge role in the digestive process is bile. Bile is produced in the liver and then stored in the gallbladder. From there, through the bile duct, it goes to the duodenum, where it is involved in the digestion of fats.
Substances present in bile enable the emulsification of fats, i.e. their breaking down into smaller particles. Fats in this form are more susceptible to the action of digestive enzymes and are more easily absorbed through the intestinal wall.
In addition to digesting food, the duodenum also plays an important role in the hormonal regulation of the entire gastrointestinal tract. In the duodenal wall there are so-called endocrine cells that produce intestinal hormones. The most important of these are secretin and cholecystokinin.
These hormones are secreted when food is transferred from the stomach to the duodenum. Secretin stimulates the secretion of pancreatic juice and bile, which allow the digestion of food present in the duodenum. At the same time, secretin inhibits further gastric emptying.
The main role of cholecystokinin is to induce contraction of the gallbladder, which causes bile to shift towards the duodenum.
Duodenum - diseases
Disease processes within the duodenum can have various causes: inflammatory, cancerous, autoimmune, infectious and congenital. Duodenal dysfunction is usually manifested in the form of epigastric discomfort, postprandial discomfort,diarrhea and malabsorption disorders.
The latter can, in extreme cases, lead to malnutrition and severe nutrient deficiencies.
In the diagnosis of duodenal diseases, standard imaging tests (X-ray, ultrasound, CT of the abdominal cavity) are not always sufficient. Often it is necessary to view the duodenum "from the inside" with the help of a special camera inserted into the lumen of the gastrointestinal tract. This test is called a gastroduodenoscopy.
Duodenal ulcer
The duodenum is a relatively common location of peptic ulcers, i.e. defects in the mucosa that cause pain and bleeding. It is believed that in the formation of duodenal ulcers, infection with the bacterium Helicobacter pylori, smoking, and taking the so-called non-steroidal anti-inflammatory drugs (such as ibuprofen, naproxen or the popular aspirin).
In most cases, duodenal ulcers are treated conservatively. The therapy uses antibiotics against Helicobacter pylori and drugs that reduce gastric acid secretion (PPIs).
In addition, it is necessary to modify the lifestyle (avoiding tobacco, non-steroidal anti-inflammatory drugs, food products that aggravate ailments). Surgical treatment of duodenal ulcers is reserved for the most severe cases, complicated by severe haemorrhage or perforation of the duodenal wall.
Duodenal diverticula
Diverticula are small protrusions of the gastrointestinal wall that can occur in all its sections. The vast majority of duodenal diverticula do not cause any discomfort and are detected accidentally.
In such cases, usually they are not treated. The indications for medical intervention are complications of diverticula, such as inflammation, bleeding or perforation (perforation). The diverticulum should then be removed surgically or endoscopically.
Parasitic diseases of the duodenum
The duodenum is a section of the gastrointestinal tract, which is particularly "fond of" for a certain species of parasite. Giardia lamblia is a type of protozoan that causes a disease called giardiasis (also giardiasis).
The course of the infection depends on the patient's immune status - in many cases the disease is completely asymptomatic. Symptomatic symptoms may include abdominal pain, watery diarrhea, nausea and loss of appetite.
Lambliosis in children may cause disturbances in the absorption of nutrients, and consequently inhibition of growth and psychomotor development. Antiparasitic drugs such as tinidazole, albendazole are effective in the treatment of lambliosisand metronidazole.
Congenital defects of the duodenum
The duodenum develops around the 6th week of gestation. Abnormalities during fetal development can lead to congenital malformations of the duodenum. The most common of them is atresia, i.e. congenital atresia of the duodenum.
Duodenal atresia may accompany congenital syndromes, including Down's syndrome relatively often.
Symptoms of duodenal atresia appear shortly after birth - the baby is unable to eat, and vomiting appears after feeding. Surgical correction is the only treatment for duodenal atresia.
Duodenal neoplasms
Both benign and malignant neoplasms can occur in the duodenum, the latter being extremely rare. Benign duodenal tumors are most often adenomas, also known as polyps.
Polyps are not malignant but can cause periodic bleeding. In addition, it is believed that some polyps can become malignant and are usually removed by endoscopy or surgery.
The most common malignant neoplasm of the duodenum is duodenal cancer, however, compared to other neoplasms of the gastrointestinal tract (colorectal cancer, gastric cancer), it is extremely rare.
Duodenal cancer has no specific symptoms. Its diagnosis is obtained by biopsy of material collected during endoscopic examination. The most effective method of treatment of duodenal cancer is surgical complete excision of the tumor.