Editing Small intestine (section)

===Parts===
[[File:Blausen 0817 SmallIntestine Anatomy.png|thumb|Labeled diagram of the small intestine and its surrounding structures]]

The small intestine is divided into three structural parts.
* The '''[[duodenum]]''' is a short structure ranging from {{Convert|20-25|cm|abbr=on|frac=2}} in length, and shaped like a "C".<ref name=GRAYS2005>{{cite book|last=Drake|first=Richard L.|title=Gray's anatomy for students|year=2005|publisher=Elsevier/Churchill Livingstone|location=Philadelphia|isbn=978-0-8089-2306-0|author2=Vogl, Wayne |author3=Tibbitts, Adam W.M. Mitchell  |author4=illustrations by Richard |author5= Richardson, Paul |page=273}}</ref> It surrounds the head of the pancreas. It receives gastric [[chyme]] from the stomach, together with digestive juices from the [[pancreas]] ([[digestive enzymes]]) and the [[liver]] ([[bile]]). The digestive enzymes break down proteins and bile [[emulsify|emulsifies]] fats into [[micelles]]. The [[duodenum]] contains [[Brunner's glands]], which produce a mucus-rich alkaline secretion containing [[bicarbonate]]. These secretions, in combination with bicarbonate from the pancreas, neutralize the stomach acids contained in gastric chyme.
* The '''[[jejunum]]''' is the midsection of the small intestine, connecting the duodenum to the ileum. It is about {{Convert|2.5|m|ft|abbr=on|frac=2}} long, and contains the [[circular folds]], and [[intestinal villus|intestinal villi]] that increase its surface area. Products of digestion (sugars, amino acids, and fatty acids) are absorbed into the bloodstream here. The [[suspensory muscle of duodenum]] marks the division between the duodenum and the jejunum.
* The '''[[ileum]]''': The final section of the small intestine. It is about 3 m (9.8 feet) long, and contains villi similar to the jejunum. It absorbs mainly [[vitamin B12]] and [[bile acids]], as well as any other remaining nutrients. The ileum joins to the [[cecum]] of the [[large intestine]] at the [[ileocecal junction]].{{cn|date=May 2022}}

The jejunum and ileum are suspended in the [[abdominal cavity]] by [[mesentery]]. The mesentery is part of the [[peritoneum]]. Arteries, veins, lymph vessels and nerves travel within the mesentery.<ref name=GRAYS2005C>{{cite book|last=Drake|first=Richard L.|title=Gray's anatomy for students|year=2005|publisher=Elsevier/Churchill Livingstone|location=Philadelphia|isbn=978-0-8089-2306-0|author2=Vogl, Wayne |author3=Tibbitts, Adam W.M. Mitchell  |author4=illustrations by Richard |author5= Richardson, Paul |page=271}}</ref>