Duodenum

Last updated
Duodenum
Tractus intestinalis duodenum.svg
Image of the gastrointestinal tract, with the duodenum highlighted.
Duodenumanatomy.jpg
Diagram of the human duodenum with major parts labelled
Details
Pronunciation /ˌdjuːəˈdiːnəm/ , US also /djuˈɒdɪnəm/ [1]
Precursor Foregut (1st and 2nd parts), Midgut (3rd and 4th part)
Part of Small intestine
System Digestive system
Artery Inferior pancreaticoduodenal artery, Superior pancreaticoduodenal artery
Vein Pancreaticoduodenal veins
Nerve celiac ganglia, vagus [2]
Identifiers
MeSH D004386
TA98 A05.6.02.001
TA2 2944
FMA 7206
Anatomical terminology
Stomach colon rectum diagram-en.svg
Major parts of the
Gastrointestinal tract
Upper gastrointestinal tract
Lower gastrointestinal tract
See also

The duodenum is the first section of the small intestine [3] in most higher vertebrates, including mammals, reptiles, and birds. In mammals it may be the principal site for iron absorption. The duodenum precedes the jejunum and ileum and is the shortest part of the small intestine.

Contents

In humans, the duodenum is a hollow jointed tube about 25–38 centimetres (10–15 inches) long connecting the stomach to the middle part of the small intestine. [4] [5] It begins with the duodenal bulb and ends at the suspensory muscle of duodenum. [6] Duodenum can be divided into four parts: the first (superior), the second (descending), the third (transverse) and the fourth (ascending) parts. [5]

Overview

The duodenum is the first section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear, and the terms anterior intestine or proximal intestine may be used instead of duodenum. [7] In mammals the duodenum may be the principal site for iron absorption. [8]

In humans, the duodenum is a C-shaped hollow jointed tube, 25–38 centimetres (10–15 inches) in length, lying adjacent to the stomach (and connecting it to the small intestine). It is divided anatomically into four sections. The first part lies within the peritoneum but its other parts are retroperitoneal. [9] : 273 

Parts

The first part, or superior part, of the duodenum is a continuation from the pylorus to transpyloric plane. It is superior to the rest of the segments, at the vertebral level of L1. The duodenal bulb, about 2 cm (3⁄4 in) long, is the first part of the duodenum and is slightly dilated. The duodenal bulb is a remnant of the mesoduodenum, a mesentery that suspends the organ from the posterior abdominal wall in fetal life. [10] The first part of the duodenum is mobile, and connected to the liver by the hepatoduodenal ligament of the lesser omentum. The first part of the duodenum ends at the corner, the superior duodenal flexure. [9] : 273 

Relations:[ citation needed ]

The second part, or descending part, of the duodenum begins at the superior duodenal flexure. It goes inferior to the lower border of vertebral body L3, before making a sharp turn medially into the inferior duodenal flexure, the end of the descending part. [9] : 274 

The pancreatic duct and common bile duct enter the descending duodenum, through the major duodenal papilla. The second part of the duodenum also contains the minor duodenal papilla, the entrance for the accessory pancreatic duct. The junction between the embryological foregut and midgut lies just below the major duodenal papilla. [9] : 274 

The third part, or horizontal part or inferior part of the duodenum is 10~12 cm in length. It begins at the inferior duodenal flexure and passes transversely to the left, passing in front of the inferior vena cava, abdominal aorta and the vertebral column. The superior mesenteric artery and vein are anterior to the third part of duodenum. [9] : 274  This part may be compressed between the aorta and SMA causing superior mesenteric artery syndrome.

The fourth part, or ascending part, of the duodenum passes upward, joining with the jejunum at the duodenojejunal flexure. The fourth part of the duodenum is at the vertebral level L3, and may pass directly on top, or slightly to the left, of the aorta. [9] : 274 

Blood supply

The duodenum receives arterial blood from two different sources. The transition between these sources is important as it demarcates the foregut from the midgut. Proximal to the 2nd part of the duodenum (approximately at the major duodenal papilla – where the bile duct enters) the arterial supply is from the gastroduodenal artery and its branch the superior pancreaticoduodenal artery. Distal to this point (the midgut) the arterial supply is from the superior mesenteric artery (SMA), and its branch the inferior pancreaticoduodenal artery supplies the 3rd and 4th sections. The superior and inferior pancreaticoduodenal arteries (from the gastroduodenal artery and SMA respectively) form an anastomotic loop between the celiac trunk and the SMA; so there is potential for collateral circulation here.

The venous drainage of the duodenum follows the arteries. Ultimately these veins drain into the portal system, either directly or indirectly through the splenic or superior mesenteric vein and then to portal vein.

Lymphatic drainage

The lymphatic vessels follow the arteries in a retrograde fashion. The anterior lymphatic vessels drain into the pancreatoduodenal lymph nodes located along the superior and inferior pancreatoduodenal arteries and then into the pyloric lymph nodes (along the gastroduodenal artery). The posterior lymphatic vessels pass posterior to the head of the pancreas and drain into the superior mesenteric lymph nodes. Efferent lymphatic vessels from the duodenal lymph nodes ultimately pass into the celiac lymph nodes.

Histology

Under microscopy, the duodenum has a villous mucosa. This is distinct from the mucosa of the pylorus, which directly joins to the duodenum. Like other structures of the gastrointestinal tract, the duodenum has a mucosa, submucosa, muscularis externa, and adventitia. Glands line the duodenum, known as Brunner's glands, which secrete mucus and bicarbonate in order to neutralise stomach acids. These are distinct glands not found in the ileum or jejunum, the other parts of the small intestine. [11] : 274–275 

Variation

The duodenum's close anatomical association with the pancreas creates differences in function based on the position and orientation of the organs. The congenital abnormality, annular pancreas, causes a portion of the pancreas to encircle the duodenum. In an extramural annular pancreas, the pancreatic duct encircles the duodenum which results in gastrointestinal obstruction. An intramural annular pancreas is characterized by pancreatic tissue that is fused with the duodenal wall, causing duodenal ulceration. [12]

Gene and protein expression

About 20,000 protein coding genes are expressed in human cells and 70% of these genes are expressed in the normal duodenum. [13] [14] Some 300 of these genes are more specifically expressed in the duodenum with very few genes expressed only in the duodenum. The corresponding specific proteins are expressed in the duodenal mucosa, and many of these are also expressed in the small intestine, such as alanine aminopeptidase, a digestive enzyme, angiotensin-converting enzyme, involved in controlling blood pressure, and RBP2, a protein involved in the uptake of vitamin A. [15]

Function

The duodenum is largely responsible for the breakdown of food in the small intestine, using enzymes. The duodenum also regulates the rate of emptying of the stomach via hormonal pathways. Secretin and cholecystokinin are released from cells in the duodenal epithelium in response to acidic and fatty stimuli present there when the pylorus opens and emits gastric chyme into the duodenum for further digestion. These cause the liver and gallbladder to release bile, and the pancreas to release bicarbonate and digestive enzymes such as trypsin, lipase and amylase into the duodenum as they are needed.[ citation needed ]

The villi of the duodenum have a leafy-looking appearance, which is a histologically identifiable structure. Brunner's glands, which secrete mucus, are only found in the duodenum. The duodenum wall consists of a very thin layer of cells that form the muscularis mucosae.

Clinical significance

Ulceration

Ulcers of the duodenum commonly occur because of infection by the bacteria Helicobacter pylori . These bacteria, through a number of mechanisms, erode the protective mucosa of the duodenum, predisposing it to damage from gastric acids. The first part of the duodenum is the most common location of ulcers since it is where the acidic chyme meets the duodenal mucosa before mixing with the alkaline secretions of the duodenum. [16] Duodenal ulcers may cause recurrent abdominal pain and dyspepsia, and are often investigated using a urea breath test to test for the bacteria, and endoscopy to confirm ulceration and take a biopsy. If managed, these are often managed through antibiotics that aim to eradicate the bacteria, and proton-pump inhibitors and antacids to reduce the gastric acidity. [17]

Celiac disease

The British Society of Gastroenterology guidelines specify that a duodenal biopsy is required for the diagnosis of adult celiac disease. The biopsy is ideally performed at a moment when the patient is on a gluten-containing diet. [18]

Cancer

Duodenal cancer is a cancer in the first section of the small intestine. Cancer of the duodenum is relatively rare compared to stomach cancer and colorectal cancer; malignant tumors in the duodenum constitute only around 0.3% of all the gastrointestinal tract tumors but around half of cancerous tissues that develop in the small intestine. [19] Its histology is often observed to be adenocarcinoma, meaning that the cancerous tissue arises from glandular cells in the epithelial tissue lining the duodenum. [20]

Inflammation

Inflammation of the duodenum is referred to as duodenitis. There are multiple known causes. [21] Celiac disease and inflammatory bowel disease are two of the known causes. [22]

Etymology

The name duodenum is Medieval Latin, short for intestīnum duodēnum digitōrum, meaning intestine of twelve finger-widths (in length), genitive pl. of duodēnī, twelve each, from Latin duodeni "twelve each" (from duodecim "twelve"). Coined by Gerard of Cremona (d. 1187) in his Latin translation of "Canon Avicennae," "اثنا عشر" itself a loan-translation of Greek dodekadaktylon, literally "twelve fingers long." The intestine part was so called by the Greek physician Herophilus (c. 335–280 BCE) for its length, about equal to the breadth of 12 fingers. [23]

Many languages retain a similar etymology for this word. For example, German Zwölffingerdarm, Dutch Twaalfvingerige darm and Turkish Oniki parmak bağırsağı.

Additional images

See also

Related Research Articles

<span class="mw-page-title-main">Pancreas</span> Organ of the digestive system and endocrine system of vertebrates

The pancreas is an organ of the digestive system and endocrine system of vertebrates. In humans, it is located in the abdomen behind the stomach and functions as a gland. The pancreas is a mixed or heterocrine gland, i.e., it has both an endocrine and a digestive exocrine function. 99% of the pancreas is exocrine and 1% is endocrine. As an endocrine gland, it functions mostly to regulate blood sugar levels, secreting the hormones insulin, glucagon, somatostatin and pancreatic polypeptide. As a part of the digestive system, it functions as an exocrine gland secreting pancreatic juice into the duodenum through the pancreatic duct. This juice contains bicarbonate, which neutralizes acid entering the duodenum from the stomach; and digestive enzymes, which break down carbohydrates, proteins and fats in food entering the duodenum from the stomach.

<span class="mw-page-title-main">Stomach</span> Digestive organ

The stomach is a muscular, hollow organ in the gastrointestinal tract of humans and many other animals, including several invertebrates. The stomach has a dilated structure and functions as a vital organ in the digestive system. The stomach is involved in the gastric phase of digestion, following chewing. It performs a chemical breakdown by means of enzymes and hydrochloric acid.

<span class="mw-page-title-main">Small intestine</span> Organ in the gastrointestinal tract

The small intestine or small bowel is an organ in the gastrointestinal tract where most of the absorption of nutrients from food takes place. It lies between the stomach and large intestine, and receives bile and pancreatic juice through the pancreatic duct to aid in digestion. The small intestine is about 5.5 metres long and folds many times to fit in the abdomen. Although it is longer than the large intestine, it is called the small intestine because it is narrower in diameter.

<span class="mw-page-title-main">Gallbladder</span> Organ in humans and other vertebrates

In vertebrates, the gallbladder, also known as the cholecyst, is a small hollow organ where bile is stored and concentrated before it is released into the small intestine. In humans, the pear-shaped gallbladder lies beneath the liver, although the structure and position of the gallbladder can vary significantly among animal species. It receives bile, produced by the liver, via the common hepatic duct, and stores it. The bile is then released via the common bile duct into the duodenum, where the bile helps in the digestion of fats.

<span class="mw-page-title-main">Abdominal aorta</span> Largest artery in the abdomen

In human anatomy, the abdominal aorta is the largest artery in the abdominal cavity. As part of the aorta, it is a direct continuation of the descending aorta.

<span class="mw-page-title-main">Digestive enzyme</span> Class of enzymes

Digestive enzymes are a group of enzymes that break down polymeric macromolecules into their smaller building blocks, in order to facilitate their absorption into the cells of the body. Digestive enzymes are found in the digestive tracts of animals and in the tracts of carnivorous plants, where they aid in the digestion of food, as well as inside cells, especially in their lysosomes, where they function to maintain cellular survival. Digestive enzymes of diverse specificities are found in the saliva secreted by the salivary glands, in the secretions of cells lining the stomach, in the pancreatic juice secreted by pancreatic exocrine cells, and in the secretions of cells lining the small and large intestines.

<span class="mw-page-title-main">Gastrointestinal disease</span> Medical condition

Gastrointestinal diseases refer to diseases involving the gastrointestinal tract, namely the esophagus, stomach, small intestine, large intestine and rectum, and the accessory organs of digestion, the liver, gallbladder, and pancreas.

<span class="mw-page-title-main">Pancreaticoduodenectomy</span> Major surgical procedure involving the pancreas, duodenum, and other organs

A pancreaticoduodenectomy, also known as a Whipple procedure, is a major surgical operation most often performed to remove cancerous tumours from the head of the pancreas. It is also used for the treatment of pancreatic or duodenal trauma, or chronic pancreatitis. Due to the shared blood supply of organs in the proximal gastrointestinal system, surgical removal of the head of the pancreas also necessitates removal of the duodenum, proximal jejunum, gallbladder, and, occasionally, part of the stomach.

<span class="mw-page-title-main">Suspensory muscle of duodenum</span> Muscle between the duodenum and jejunum

The suspensory muscle of duodenum is a thin muscle connecting the junction between the duodenum and jejunum, as well as the duodenojejunal flexure to connective tissue surrounding the superior mesenteric and coeliac arteries. The suspensory muscle most often connects to both the third and fourth parts of the duodenum, as well as the duodenojejunal flexure, although the attachment is quite variable.

<span class="mw-page-title-main">Duodenal cancer</span> Medical condition

Duodenal cancer is a cancer in the first section of the small intestine known as the duodenum. Cancer of the duodenum is relatively rare compared to stomach cancer and colorectal cancer. Its histology is usually adenocarcinoma.

<span class="mw-page-title-main">Gastroduodenal artery</span>

In anatomy, the gastroduodenal artery is a small blood vessel in the abdomen. It supplies blood directly to the pylorus and proximal part of the duodenum. It also indirectly supplies the pancreatic head.

<span class="mw-page-title-main">Hepatic artery proper</span>

The hepatic artery proper is the artery that supplies the liver and gallbladder. It raises from the common hepatic artery, a branch of the celiac artery.

<span class="mw-page-title-main">Superior pancreaticoduodenal artery</span> Artery

The superior pancreaticoduodenal artery is an artery that supplies blood to the duodenum and pancreas.

<span class="mw-page-title-main">Foregut</span> Anterior part of the gastrointestinal tract

The foregut in humans is the anterior part of the alimentary canal, from the distal esophagus to the first half of the duodenum, at the entrance of the bile duct. Beyond the stomach, the foregut is attached to the abdominal walls by mesentery. The foregut arises from the endoderm, developing from the folding primitive gut, and is developmentally distinct from the midgut and hindgut. Although the term “foregut” is typically used in reference to the anterior section of the primitive gut, components of the adult gut can also be described with this designation. Pain in the epigastric region, just below the intersection of the ribs, typically refers to structures in the adult foregut.

<span class="mw-page-title-main">Pancreatic branches of splenic artery</span>

The pancreatic branches or pancreatic arteries are numerous small vessels derived from the splenic artery as it runs behind the upper border of the pancreas, supplying its body and tail.

<span class="mw-page-title-main">Hepatic plexus</span>

The hepatic plexus is a sympathetic and parasympathetic nerve plexus that provides innervation to the parenchyma of the liver as well as contributing innervation to some other abdominal structures.

<span class="mw-page-title-main">Hemosuccus pancreaticus</span> Medical condition

Hemosuccus pancreaticus is a rare cause of hemorrhage in the gastrointestinal tract. It is caused by a bleeding source in the pancreas, pancreatic duct, or structures adjacent to the pancreas, such as the splenic artery, that bleed into the pancreatic duct, which is connected with the bowel at the duodenum, the first part of the small intestine. Patients with hemosuccus may develop symptoms of gastrointestinal hemorrhage, such as blood in the stools, maroon stools, or melena, which is a dark, tarry stool caused by digestion of red blood cells. They may also develop abdominal pain. It is associated with pancreatitis, pancreatic cancer and aneurysms of the splenic artery. Hemosuccus may be identified with endoscopy (esophagogastroduodenoscopy), where fresh blood may be seen from the pancreatic duct. Alternatively, angiography may be used to inject the celiac axis to determine the blood vessel that is bleeding. This may also be used to treat hemosuccus, as embolization of the end vessel may terminate the hemorrhage. However, a distal pancreatectomy—surgery to remove of the tail of the pancreas—may be required to stop the hemorrhage.

<span class="mw-page-title-main">Hepatic lymph nodes</span> Lymph nodes on the common hepatic artery

The hepatic lymph nodes consist of the following groups:

The superior mesenteric vessels are composed of the superior mesenteric artery and the superior mesenteric vein.

<span class="mw-page-title-main">Human digestive system</span> Digestive system in humans

The human digestive system consists of the gastrointestinal tract plus the accessory organs of digestion. Digestion involves the breakdown of food into smaller and smaller components, until they can be absorbed and assimilated into the body. The process of digestion has three stages: the cephalic phase, the gastric phase, and the intestinal phase.

References

  1. ↑ Jones, Daniel (2011). Roach, Peter; Setter, Jane; Esling, John (eds.). Cambridge English Pronouncing Dictionary (18th ed.). Cambridge University Press. ISBN   978-0-521-15255-6.
  2. ↑ Nosek, Thomas M. "Section 6/6ch2/s6ch2_30". Essentials of Human Physiology. Archived from the original on 2016-03-24.
  3. ↑ "NCI Dictionary of Cancer Terms". National Cancer Institute. Retrieved 2022-06-07. The first part of the small intestine. It connects to the stomach. The duodenum helps to further digest food coming from the stomach. It absorbs nutrients (vitamins, minerals, carbohydrates, fats, proteins) and water from food so they can be used by the body.
  4. ↑ "Duodenum: MedlinePlus Medical Encyclopedia". MedlinePlus. Retrieved 2022-06-07. It is located between the stomach and the middle part of the small intestine. After foods mix with stomach acid, they move into the duodenum, where they mix with bile from the gallbladder and digestive juices from the pancreas.
  5. 1 2 Nolan, D. J. (2002). "Radiology of the Duodenum". Radiological Imaging of the Small Intestine. Medical Radiology. Berlin, Heidelberg: Springer Berlin Heidelberg. pp. 247–259. doi:10.1007/978-3-642-56231-0_6. ISBN   978-3-642-62993-8. ISSN   0942-5373. duodenum is a C-shaped hollow organ forming an incomplete circle around the head of the pancreas. ...it is normally examined as part of the upper gastrointestinal tract.
  6. ↑ van Gijn J; Gijselhart JP (2011). "Treitz and his ligament". Ned. Tijdschr. Geneeskd. 155 (8): A2879. PMID   21557825.
  7. ↑ Guillaume, Jean; Praxis Publishing; Sadasivam Kaushik; Pierre Bergot; Robert Metailler (2001). Nutrition and Feeding of Fish and Crustaceans. Springer. p. 31. ISBN   978-1-85233-241-9 . Retrieved 2009-01-09.
  8. ↑ Latunde-Dada GO; Van der Westhuizen J; Vulpe CD; et al. (2002). "Molecular and functional roles of duodenal cytochrome B (Dcytb) in iron metabolism". Blood Cells Mol. Dis. 29 (3): 356–60. doi:10.1006/bcmd.2002.0574. PMID   12547225.
  9. 1 2 3 4 5 6 Drake, Richard L.; Vogl, Wayne; Tibbitts, Adam W.M. Mitchell; illustrations by Richard; Richardson, Paul (2005). Gray's anatomy for students. Philadelphia: Elsevier/Churchill Livingstone. ISBN   978-0-8089-2306-0.
  10. ↑ Singh, Inderbir; GP Pal (2012). "13". Human Embryology (9 ed.). Delhi: Macmillan Publishers India. p. 163. ISBN   978-93-5059-122-2.
  11. ↑ Deakin, Barbara Young; et al. (2006). Wheater's functional histology : a text and colour atlas (5th ed.). [Edinburgh?]: Churchill Livingstone/Elsevier. ISBN   978-0-443-06850-8.
  12. ↑ Borghei, Peyman; Sokhandon, Farnoosh; Shirkhoda, Ali; Morgan, Desiree E. (January 2013). "Anomalies, Anatomic Variants, and Sources of Diagnostic Pitfalls in Pancreatic Imaging". Radiology. 266 (1): 28–36. doi:10.1148/radiol.12112469. ISSN   0033-8419. PMID   23264525.
  13. ↑ "The human proteome in duodenum - The Human Protein Atlas". www.proteinatlas.org. Retrieved 2017-09-26.
  14. ↑ Uhlén, Mathias; Fagerberg, Linn; Hallström, Björn M.; Lindskog, Cecilia; Oksvold, Per; Mardinoglu, Adil; Sivertsson, Åsa; Kampf, Caroline; Sjöstedt, Evelina (2015-01-23). "Tissue-based map of the human proteome". Science. 347 (6220): 1260419. doi:10.1126/science.1260419. ISSN   0036-8075. PMID   25613900. S2CID   802377.
  15. ↑ Gremel, Gabriela; Wanders, Alkwin; Cedernaes, Jonathan; Fagerberg, Linn; Hallström, Björn; Edlund, Karolina; Sjöstedt, Evelina; Uhlén, Mathias; Pontén, Fredrik (2015-01-01). "The human gastrointestinal tract-specific transcriptome and proteome as defined by RNA sequencing and antibody-based profiling". Journal of Gastroenterology. 50 (1): 46–57. doi:10.1007/s00535-014-0958-7. ISSN   0944-1174. PMID   24789573. S2CID   21302849.
  16. ↑ Smith, Margaret E. The Digestive System.
  17. ↑ Colledge, Nicki R.; Walker, Brian R.; Ralston, Stuart H., eds. (2010). Davidson's principles and practice of medicine (21st ed.). Edinburgh: Churchill Livingstone/Elsevier. pp. 871–874. ISBN   978-0-7020-3085-7.
  18. ↑ Ludvigsson, J. F.; Bai, J. C.; Biagi, F.; Card, T. R.; Ciacci, C.; Ciclitira, P. J.; Green, P. H. R.; Hadjivassiliou, M.; Holdoway, A.; van Heel, D. A.; Kaukinen, K.; Leffler, D. A.; Leonard, J. N.; Lundin, K. E. A.; McGough, N.; Davidson, M.; Murray, J. A.; Swift, G. L.; Walker, M. M.; Zingone, F.; Sanders, D. S. (2014). "Diagnosis and management of adult coeliac disease: Guidelines from the British Society of Gastroenterology". Gut. 63 (8): 1210–1228. doi:10.1136/gutjnl-2013-306578. ISSN   0017-5749. PMC   4112432 . PMID   24917550.
  19. ↑ Fagniez, Pierre-Louis; Rotman, Nelly (2001). Malignant tumors of the duodenum. Zuckschwerdt.
  20. ↑ https://www.cancer.gov/publications/dictionaries/cancer-terms/def/adenocarcinoma.{{cite web}}: Missing or empty |title= (help)
  21. ↑ Serra S, Jani PA (2006). "An approach to duodenal biopsies". J. Clin. Pathol. 59 (11): 1133–50. doi:10.1136/jcp.2005.031260. PMC   1860495 . PMID   16679353.
  22. ↑ Alper, Arik; Hardee, Steven; Rojas-velasquez, Danilo; Escalera, Sandra; Morotti, Raffaella A; Pashankar, Dinesh S. (February 2016). "Prevalence, clinical, endoscopic and pathological features of duodenitis in children". Journal of Pediatric Gastroenterology and Nutrition. 62 (2): 314–316. doi:10.1097/MPG.0000000000000942. ISSN   0277-2116. PMC   4724230 . PMID   26252915.
  23. ↑ "duodenum - Origin and meaning of duodenum by Online Etymology Dictionary". www.etymonline.com.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.