Editing Small intestine (section)

{{Short description|Organ in the gastrointestinal tract}}
{{Infobox anatomy
| Name =Small intestine
| Latin = intestinum tenue
| Image = Tractus intestinalis intestinum tenue.svg
| Caption = Small intestine and surrounding structures
| Image2 =
| Caption2 =
| Precursor =
| PartOf = [[Gastrointestinal tract]]
| System = [[Digestive system]]
| Artery = [[Superior mesenteric artery]], [[jejunal arteries]], [[ileal arteries]]
| Vein  = [[Hepatic portal vein]], [[superior mesenteric vein]]
| Nerve = [[Celiac ganglia]], [[vagus]]<ref>{{cite book| title= Essentials of Human Physiology| first= Thomas M. |last= Nosek| chapter=Section 6/6ch2/s6ch2_30 |chapter-url=http://humanphysiology.tuars.com/program/section6/6ch2/s6ch2_30.htm |archive-url=https://web.archive.org/web/20160324124828/http://humanphysiology.tuars.com/program/section6/6ch2/s6ch2_30.htm|archive-date=2016-03-24}}</ref>
| Lymph = [[Intestinal lymph trunk]]
|Width=200}}
{{Gastrointestinal tract sidebar}}
The '''small intestine''' or '''small bowel''' is an [[organ (anatomy)|organ]] in the [[human gastrointestinal tract|gastrointestinal tract]] where most of the [[#Absorption|absorption]] of [[nutrient]]s 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 {{Convert|5.5|m|abbr=off}} 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.

The small intestine has three distinct regions – the [[duodenum]], [[jejunum]], and [[ileum]]. The duodenum, the shortest, is where preparation for absorption through small finger-like protrusions called [[intestinal villus|intestinal villi]] begins.<ref>[http://www.britannica.com/EBchecked/topic/275485/human-body human body | Britannica.com<!-- Bot generated title -->]</ref> The jejunum is specialized for the absorption through its lining by [[enterocytes]]: small nutrient particles which have been previously digested by [[enzymes]] in the duodenum.  The main function of the ileum is to absorb [[vitamin B12|vitamin B<sub>12</sub>]], [[bile salts]], and whatever products of digestion that were not absorbed by the jejunum.