Gastrointestinal Tract - Intestine Development: Difference between revisions
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* Duodenum (adult 25 cm length) | * Duodenum (adult 25 cm length) | ||
* Jejunum (adult 1.4 m length) | * Jejunum (adult 1.4 m length) | ||
* Ileum (adult 3.5 length) | * Ileum (adult 3.5 m length) | ||
Large intestine or bowel | Large intestine or bowel |
Revision as of 14:30, 30 April 2011
Introduction
The part of the gastrointestinal tract (GIT) lying between the stomach and anus, is described as the intestines or bowel. This region is further divided anatomically and functionally into the small intestine or bowel (duodenum, jejunum and ileum) and large intestine or bowel (cecum and colon). Initially development concerns the midgut region, connected to the yolk sac, and the hindgut region, ending at the cloacal membrane. This is followed by two mechanical processes of elongation and rotation. Elongation, growth in length, leaves the midgut "herniated" at the umbilicus and external to the abdomen. Rotation, around a mesentery axis, establishes the anatomical position of the large intestine within the peritoneal space.
Migration of neural crest cells into the wall establishes the enteric nervous system, which has a role in peristalsis and secretion. Prenatally, secretions also accumulate in this region and are the first postnatal bowel movement, the meconium.
Like most of the gut, this region is not "functional" until after birth, when development continues by populating the large intestine with commensal bacteria and the establishment of the immune structure in the wall.
Some Recent Findings
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Adult Intestine
Intestinal Regions
Small intestine or bowel
- Duodenum (adult 25 cm length)
- Jejunum (adult 1.4 m length)
- Ileum (adult 3.5 m length)
Large intestine or bowel
- Cecum (caecum)
- Vermiform appendix ("appendix", adult 2 to 20 cm length)
- Colon
- Ascending colon (adult 25 cm length)
- Transverse colon
- Descending colon
- Sigmoid colon
Intestinal Functions
Small Intestine
- absorption of nutrients and minerals found in food
- Duodenum -principal site for iron absorption
Cecum
- connects the ileum with the ascending colon
- separated by the ileocecal valve (ICV, Bauhin's valve)
- connected to the vermiform appendix ("appendix")
Colon
- absorbs fluid, water and salts, from solid wastes
- site of commensal bacteria (flora) fermentation of unabsorbed material
Embryonic Development
Week 4
Quicktime | Flash |
Week 8
Late embryonic small intestine commencing at the duodenum, continuing as ventrally herniated and returning to join the colon.
Molecular Factors
- Cdx (Caudal-type homeobox) group of ParaHox genes (mouse Cdx1, Cdx2 and Cdx4)[2]
Abnormalities
- Abnormality Links: Gastrointestinal Tract - Abnormalities | Intestine Development | Gastrointestinal Tract
- Lumen Abnormalities: Image - Duplication sites | Pyloric atresia | Jejunal atresia
- Rotation: Image - Midgut volvulus | Image - Intestinal malrotation | Image - Cecal volvulus | Image - Sigmoid volvulus | Ladd's band
- Meckel's Diverticulum: Meckel's Image 1 | Meckel's Image 2 | Meckel's Image 3 |
- Intestinal Aganglionosis: Image - Ostomy | Image - Stoma | Surgery 1 | Surgery 2 | Surgery 3
Cite this page: Hill, M.A. (2024, May 3) Embryology Gastrointestinal Tract - Intestine Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Gastrointestinal_Tract_-_Intestine_Development
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G
References
Reviews
Articles
Search Pubmed
Search Bookshelf Intestine Development
Search Pubmed Now: Intestine Embryology | Intestine Development
Glossary Links
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Cite this page: Hill, M.A. (2024, May 3) Embryology Gastrointestinal Tract - Intestine Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Gastrointestinal_Tract_-_Intestine_Development
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G