Editing Gastrointestinal tract (section)

====Gastrointestinal microbiota====
{{Main article|Gut microbiota}}
[[File:Microbiome.jpg|thumb|upright=1.6|Diagram of human [[microbiota]] depicted in various regions of the gastrointestinal tract]]
The large intestine contains multiple types of [[bacteria]], and other [[microorganism]]s that can break down molecules the human body cannot process alone,<ref name="Knight2002">{{Cite book|url=https://books.google.com/books?id=G0sCAAAACAAJ|title=Science of Everyday Things: Real-life biology|isbn=9780787656348|volume=4|last1=Knight|first1=Judson|year=2002|publisher=Gale}}</ref><ref>{{cite journal|last1=Hillman|first1=Ethan T|last2=Lu|first2=Hang|last3=Yao|first3=Tianmang|last4=Nakatsu|first4=Cindy H|title=Minireview: Microbial Ecology along the Gastrointestinal Tract|journal=Microbes Environ|date=2017|volume=32|issue=4|pages=300–313|doi=10.1264/jsme2.ME17017|pmid=29129876 |pmc=5745014 |url=https://www.jstage.jst.go.jp/article/jsme2/32/4/32_ME17017/_html/-char/en|access-date=30 March 2025}}</ref> demonstrating a [[symbiosis|symbiotic]] relationship. These microbes are responsible for gas production at [[host–pathogen interface]], which is released as [[flatulence]]. Intestinal bacteria can also participate in biosynthesis reactions. For example, certain strains in the large intestine produce vitamin B<sub>12</sub>;<ref>{{Cite journal|last=Martens, H. Barg, M. Warren, D. Jah|first=J.-H.|date=2002-03-01|title=Microbial production of vitamin B 12|url=http://link.springer.com/10.1007/s00253-001-0902-7|journal=Applied Microbiology and Biotechnology|volume=58|issue=3|pages=275–285|doi=10.1007/s00253-001-0902-7|pmid=11935176|issn=0175-7598}}</ref> an essential compound in humans for things like DNA synthesis and red blood cell production.<ref>{{Cite web|title=Are You Getting Enough Vitamin B12? What You Need to Know|url=https://www.yalemedicine.org/news/are-you-getting-enough-vitamin-b12#:~:text=Vitamin%20B12,%20also%20called%20cobalamin,meaning%20it%20dissolves%20in%20water.|access-date=2024-11-23|website=Yale Medicine|language=en}}</ref> However, the primary function of the large intestine is water absorption from digested material (regulated by the [[hypothalamus]]) and the reabsorption of [[sodium]] and nutrients.<ref>{{cite journal|url=https://www.ncbi.nlm.nih.gov/books/NBK507857/#:~:text=The%20large%20intestine%20has%203,toward%20the%20rectum%20for%20elimination.|title=Physiology, Large Intestine|last1=Azzouz|first1=Laura L.|last2=Sharma|first2=Sandeep|publisher=StatPearls Publishing|date=31 July 2023|website=National Library of Medicine|pmid=29939634|access-date=24 March 2024}}</ref>

Beneficial [[Gut flora|intestinal bacteria]] compete with potentially harmful [[bacteria]] for space and "food", as the intestinal tract has limited resources. A ratio of 80–85% beneficial to 15–20% potentially harmful bacteria is proposed for maintaining [[homeostasis]].{{citation needed|date=May 2016}} An imbalanced ratio results in [[dysbiosis]].