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Gastrointestinal tract

The digestive passageway from mouth to anus.

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The digestive system's passageway, known as the gastrointestinal tract, runs continuously from the mouth down to the anus.[1] Among the body's largest systems, the GI tract contains the esophagus, stomach, and intestines.[1] When measured during an autopsy, the entire human GI tract has a length of roughly 9 m.[2]

Quick Facts

System
Digestive system

Facts from the source article.

Key facts and history

The small intestine is about 6 to 7 m long and its mucosal area is roughly 30 m² in an adult.[3] Most animals have a complete through-gut, but sponges, comb jellies, cnidarians, and acoels have simpler arrangements.[4] The suspensory muscle of the duodenum serves as the dividing point between the upper and lower sections of the tract.[5][6] Absorbing water and salts is the primary job of the colon, which is the longest part of the large intestine; that organ measures about 1.5 m in length.[7]

A fossil digestive tract from a Cloudinidae worm, discovered in 2020, is the oldest known and dates to roughly 550 million years ago.[8] A through-gut with both a mouth and anus is thought to have evolved within the nephrozoan clade of Bilateria, when a single ancestral orifice stretched and then closed in the middle.[9] Peristalsis is coordinated by the muscular layer's inner circular and outer longitudinal layers working together.[10] Because it contains its own enteric nervous system, the gut possesses intrinsic peristaltic activity, also called basal electrical rhythm.[10]

What the research sources say

The same source notes that the muscle layers are actually helical with different pitches, not truly longitudinal or circular.[11][10] The book "Human Embryology and Developmental Biology" explains that each gut segment gives rise to specific structures in later development.[12][13] The Yale Medicine article on vitamin B12 notes that aging can change the GI system, making it harder to absorb B12.[14] The same article reports that digestive illnesses such as celiac and Crohn's diseases can restrict vitamin B12 absorption.[14]

References

  1. Wikipedia, "Gastrointestinal tract" (CC BY-SA 4.0), which cites: Roszkowska, "Small Intestinal Bacterial Overgrowth (SIBO) and Twelve Groups of Related Diseases-Current State of Knowledge.", Biomedicines, 7 May 2024, p. 1030 (original not read by us) en.wikipedia.org
  2. Wikipedia, "Gastrointestinal tract" (CC BY-SA 4.0), which cites: G., "Anatomical study of the length of the human intestine", Surgical and Radiologic Anatomy, 2002-12-01, p. 290–294; Raines, "Variation in small bowel length: Factor in achieving total enteroscopy?", Digestive Endoscopy, 2014-05-26, p. 67–72 (original not read by us) en.wikipedia.org
  3. Wikipedia, "Gastrointestinal tract" (CC BY-SA 4.0), which cites: Roszkowska, "Small Intestinal Bacterial Overgrowth (SIBO) and Twelve Groups of Related Diseases-Current State of Knowledge.", Biomedicines, 7 May 2024, p. 1030; Drake, "Gray's anatomy for students", Elsevier/Churchill Livingstone, 2015, p. 312; Helander, "Surface area of the digestive tract - revisited", Scandinavian Journal of Gastroenterology, 2014-06-01, p. 681–689; Hall, "Guyton and Hall textbook of medical physiology", Saunders/Elsevier, 2011, p. 794 (original not read by us) en.wikipedia.org
  4. Wikipedia, "Gastrointestinal tract" (CC BY-SA 4.0), which cites: "Overview of Invertebrates", www.ck12.org, 6 October 2015; Ruppert, "Invertebrate Zoology", Brooks / Cole, 2004, p. 197 (original not read by us) en.wikipedia.org
  5. Wikipedia, "Gastrointestinal tract" (CC BY-SA 4.0) en.wikipedia.org
  6. Wikipedia, "Gastrointestinal tract" (CC BY-SA 4.0), which cites: David A. Warrell, "Oxford textbook of medicine: Sections 18-33", Oxford University Press, 2005, p. 511– (original not read by us) en.wikipedia.org
  7. Wikipedia, "Gastrointestinal tract" (CC BY-SA 4.0), which cites: Helander, "Surface area of the digestive tract - revisited", Scandinavian Journal of Gastroenterology, 2014-06-01, p. 681–689; "definition colon", www.cancer.gov, 2 February 2011 (original not read by us) en.wikipedia.org
  8. Wikipedia, "Gastrointestinal tract" (CC BY-SA 4.0), which cites: Joel, "Fossil Reveals Earth's Oldest Known Animal Guts - The find in a Nevada desert revealed an intestine inside a creature that looks like a worm made of a stack of ice cream cones.", The New York Times, 10 January 202; Schiffbauer, James D., "Discovery of bilaterian-type through-guts in cloudinomorphs from the terminal Ediacaran Period", Nature Communications, 10 January 2020 (original not read by us) en.wikipedia.org
  9. Wikipedia, "Gastrointestinal tract" (CC BY-SA 4.0), which cites: Nielsen, C., Brunet, T. & Arendt, D. Evolution of the bilaterian mouth and anus. Nat Ecol Evol 2, 1358–1376 (2018). https://doi.org/10.1038/s41559-018-0641-0; De Robertis, E. M., & Tejeda-Muñoz, N. (2022). Evo-Devo of urbilateria and its larval forms. Developmental Biology, 487, 10–20. https://doi.org/10.1016/j.yd (original not read by us) en.wikipedia.org
  10. Wikipedia, "Gastrointestinal tract" (CC BY-SA 4.0), which cites: Sarna, "Colonic Motility: From Bench Side to Bedside", Morgan & Claypool Life Sciences, 2010 (we also read that source) en.wikipedia.org
  11. Open Library record, ISBN 9781615041503 ("Colonic Motility"). CC0 (metadata); book content not read. openlibrary.org
  12. Open Library record, ISBN 9780323036498 ("Human Embryology and Developmental Biology Updated Edition"). CC0 (metadata); book content not read. openlibrary.org
  13. Wikipedia, "Gastrointestinal tract" (CC BY-SA 4.0), which cites: Bruce M. Carlson, "Human Embryology and Developmental Biology", Mosby, 2004 (we also read that source) en.wikipedia.org
  14. "Are You Getting Enough Vitamin B12? What You Need to Know", Yale Medicine. facts only, no text reused. yalemedicine.org

Each numbered sentence above was checked against the source it cites before publication. Sentences citing Wikipedia adapt text from the English Wikipedia article Gastrointestinal tract (contributors), used under CC BY-SA 4.0; this entry is available under the same licence. Other sources were used for facts only; no text or images are copied from them.

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Sources

Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.

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