Editing Stomach (section)

==Structure==
In the [[human digestive system]], the stomach lies between the [[esophagus]] and the [[duodenum]] (the first part of the [[small intestine]]). It is in the [[Quadrants and regions of abdomen#Quadrants|left upper quadrant]] of the [[abdominal cavity]]. The top of the stomach lies against the [[diaphragm (anatomy)|diaphragm]]. Lying behind the stomach is the [[pancreas]]. A large double fold of visceral [[peritoneum]] called the [[greater omentum]] hangs down from the [[Curvatures of the stomach|greater curvature]] of the stomach. Two [[sphincter]]s keep the contents of the stomach contained; the [[oesophagus#Sphincters|lower esophageal sphincter]]  (found in the cardiac region), at the junction of the esophagus and stomach, and the [[pyloric sphincter]] at the junction of the stomach with the duodenum.

The stomach is surrounded by [[parasympathetic nervous system|parasympathetic]] (inhibitor) and [[sympathetic nervous system|sympathetic]] (stimulant) [[plexuses]] (networks of [[blood vessel]]s and [[nerve]]s in the [[anterior]] gastric, [[Posterior (anatomy)|posterior]], [[Anatomical terms of location#Superior and inferior|superior]] and [[Anatomical terms of location#Superior and inferior|inferior]], celiac and myenteric), which regulate both the secretory activity of the stomach and the motor (motion) activity of its muscles.

The stomach is [[wikt:distensibility|distensible]], and can normally expand to hold about one litre of food.<ref>{{cite book |author=Sherwood, Lauralee |title=Human physiology: from cells to systems |publisher=Wadsworth Pub. Co |location=Belmont, CA |year=1997 |isbn=978-0-314-09245-8 |oclc=35270048 |url-access=registration |url=https://archive.org/details/humanphysiologyf00sher }}</ref> The shape of the stomach depends upon the degree of its distension and that of surrounding viscera, e.g. the colon.<ref name="Chaurasia2013">{{Cite book |last=Chaurasia |first=B.D. |title=Human Anatomy |publisher=CBS Publishers and Distributors |year=2013 |isbn=978-81-239-2331-4 |edition=6th |volume=2 |location=4819/XI, Prahlad Street, Ansari Road, Daryaganj, New Delhi 110002, India |pages=250–252 |chapter=19}}</ref> When empty, the stomach is somewhat J-shaped; when partially distended, it becomes pyriform in shape. In obese persons, it is more horizontal.<ref name="Chaurasia2013" /> In a newborn human baby the stomach will only be able to hold about 30 millilitres. The maximum stomach volume in adults is between 2 and 4 litres,<ref name="pmid9863573">{{cite journal |vauthors=Wenzel V, Idris AH, Banner MJ, Kubilis PS, Band R, Williams JL, etal| title=Respiratory system compliance decreases after cardiopulmonary resuscitation and stomach inflation: impact of large and small tidal volumes on calculated peak airway pressure | journal=Resuscitation |year=1998 |volume=38 |issue=2 |pages=113–8 |pmid=9863573 |doi=10.1016/S0300-9572(98)00095-1}}</ref><ref>{{cite book|author=Curtis, Helena & N. Sue Barnes|title=Invitation to Biology|edition=5|publisher=Worth|year=1994}}</ref> although volumes of up to 15 litres have been observed in extreme circumstances.<ref>Morris D. Kerstein, Barry Goldberg, Barry Panter, M. David Tilson, Howard Spiro, Gastric Infarction, Gastroenterology, Volume 67, Issue 6, 1974, Pages 1238–1239, ISSN 0016-5085, https://doi.org/10.1016/S0016-5085(19)32710-6.</ref>

=== Sections ===
{{Redirect|Cardia|the ancient Greek colony|Cardia (Thrace)}}
[[File:2414 Stomach.jpg|thumb|Diagram showing parts of the stomach]]

The human stomach can be divided into four sections, beginning at the cardia followed by the fundus, the body and the pylorus.<ref name="Tortora09">{{cite book |last1=Tortora |first1=Gerard J. |last2=Derrickson |first2=Bryan H. |title=Principles of anatomy and physiology |date=2009 |publisher=Wiley |location=Hoboken, NJ |isbn=9780470233474 |pages=937–942 |edition=12., internat. student version}}</ref><ref name=Elsevier />
* The gastric '''cardia''' is where the contents of the esophagus empty from the [[gastroesophageal sphincter]] into the cardiac orifice, the opening into the gastric cardia.<ref name=SCHWARTZ2010 /><ref name=Elsevier/> A cardiac notch at the left of the cardiac orifice, marks the beginning of the [[greater curvature]] of the stomach. A horizontal line across from the cardiac notch gives the dome-shaped region called the fundus.<ref name=Elsevier /> The cardia is a very small region of the stomach that surrounds the esophageal opening.<ref name=Elsevier />
* The '''fundus''' ({{ety|la||bottom}}) is formed in the upper curved part.
* The '''body''' or '''corpus''' is the main, central region of the stomach.
* The [[pylorus]] opens to the body of the stomach. The pylorus ({{ety|el||gatekeeper}}) connects the stomach to the [[duodenum]] at the [[pyloric sphincter]].

The cardia is defined as the region following the "z-line" of the [[gastroesophageal junction]], the point at which the [[epithelium]] changes from [[stratified squamous epithelia|stratified squamous]] to [[columnar]]. Near the cardia is the lower esophageal sphincter.<ref name=SCHWARTZ2010 >{{cite book|editor-first=F. Charles |editor-last=Brunicardi |editor2-first=Dana K. |editor2-last=Andersen |title=Schwartz's principles of surgery|date=2010|publisher=McGraw-Hill, Medical Pub. Division|location=New York|isbn=978-0071547703|edition=9th|display-editors=etal}}</ref>

=== Anatomical proximity ===
The '''stomach bed''' refers to the structures upon which the  stomach rests in mammals.<ref>[https://books.google.com/books?id=S9MvAQAAMAAJ&dq=%22stomach+bed%22&pg=RA1-PA7] Habershon, S. H. "Diseases of the Stomach: A Manual for Practitioners and Students,"Chicago Medical Book Company, 1909,  page 11.</ref><ref>[https://books.google.com/books?id=fn7TUwyORwQC&dq=%22stomach+bed%22&pg=PA157] Weber, John and Shearer, Edwin Morrill "Shearer's manual of human dissection, Eighth Edition," McGraw Hill, 1999, page 157. {{ISBN|0-07-134624-4}}.</ref> These include the [[tail of the pancreas]], [[splenic artery]], left [[kidney]], left [[suprarenal gland]], [[transverse colon]] and its [[mesocolon]], and the [[left crus of diaphragm]], and the [[left colic flexure]]. The term was introduced around 1896 by Philip Polson of the Catholic University School of Medicine, Dublin. However this was brought into disrepute by surgeon anatomist J Massey.<ref>[https://archive.org/details/transactionsroy01irelgoog/page/n434 <!-- quote="stomach bed". -->] Transactions of the Royal Academy of Medicine in Ireland, Volume 14, 1896, "Birmingham, A(mbrose), "Topographical anatomy of the spleen, pancreas, duodenum, kidneys, &c.", pages 363-385. Retrieved 29 February 2011.</ref><ref>[https://books.google.com/books?id=nKdMAQAAIAAJ&dq=%22stomach+bed%22&pg=PA524] The Lancet, Volume 1, Part 1, 22 February 1902. page 524, "Royal Academy of Medicine in Ireland." Retrieved 28 February 2012</ref><ref>[https://books.google.com/books?id=yWoBAAAAYAAJ&dq=%22stomach+bed%22+birmingham&pg=PA353] The Dublin journal of medical science, Volume 114, page 353."Reviews and bibliographical notes." Retrieved 28 February 2012.</ref>

=== Blood supply ===
[[Image:Stomach blood supply.svg|thumb|240px|Schematic image of the blood supply to the human stomach: [[left gastric artery|left]] and [[right gastric artery]], [[left gastroepiploic artery|left]] and [[right gastroepiploic artery]] and [[short gastric arteries]]<ref name=Moore150>{{cite book |author1=Anne M. R. Agur |author2=Moore, Keith L. |title=Essential Clinical Anatomy (Point (Lippincott Williams & Wilkins)) |publisher=Lippincott Williams & Wilkins |location=Hagerstown, MD |year= 2007|isbn=978-0-7817-6274-8 |oclc= 172964542}}; p. 150</ref>]]

The lesser curvature of the human stomach is supplied by the [[right gastric artery]] inferiorly and the [[left gastric artery]] superiorly, which also supplies the cardiac region. The greater curvature is supplied by the [[right gastroepiploic artery]] inferiorly and the [[left gastroepiploic artery]] superiorly. The fundus of the stomach, and also the upper portion of the greater curvature, is supplied by 5-7 [[short gastric arteries]], which arise from the splenic artery.<ref name="Chaurasia2013"/>

===Lymphatic drainage===
The two sets of [[gastric lymph nodes]] drain the stomach's tissue fluid into the lymphatic system through the [[intestinal lymph trunk]], to the [[cisterna chyli]].<ref name="Chaurasia2013"/>

===Microanatomy===
====Wall====
{{Main article|Gastrointestinal wall}}
[[Image:Gastrointestinal wall of human stomach hariadhi.svg|thumb|right|The gastrointestinal wall of the human stomach]]
[[File:Layers of the GI Tract english.svg|thumb|Layers of the gastrointestinal wall of which the stomach is a dilated part]]

Like the other parts of the [[gastrointestinal wall]], the human stomach wall from inner to outer, consists of a [[mucosa]], [[submucosa]], [[muscular layer]], [[subserosa]] and [[serosa]].<ref>{{cite web|title=University of Rochester medical center|url=https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=34&contentid=17785-1|date=2020|access-date=2021-12-19|archive-date=2021-11-19|archive-url=https://web.archive.org/web/20211119050031/https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=34&contentid=17785-1|url-status=dead}}</ref>

The inner part of the stomach wall is the [[gastric mucosa]] a mucous membrane that forms the lining of the stomach. the membrane consists of an outer layer of [[columnar epithelium]], a [[lamina propria]], and a thin layer of [[smooth muscle]] called the [[muscularis mucosa]]. Beneath the mucosa lies the [[submucosa]], consisting of [[fibrous connective tissue]].<ref>{{Cite web|title=Stomach histology|url=https://www.kenhub.com/en/library/anatomy/stomach-histology|access-date=2021-01-09|website=Kenhub|language=en}}</ref> [[Meissner's plexus]] is in this layer interior to the oblique muscle layer.<ref>{{Cite book|title=Gastrointestinal physiology : development, principles and mechanisms of regulation|last=Welcome, Menizibeya Osain|publisher=Springer|year=2018|isbn=978-3-319-91056-7|location=Cham, Switzerland|pages=628|oclc=1042217248}}</ref>

Outside of the submucosa lies the muscular layer. It consists of three layers of muscular fibres, with fibres lying at angles to each other. These are the inner oblique, middle circular, and outer longitudinal layers.<ref>{{Cite web |date=2018-07-22 |title=22.5C: Muscularis |url=https://med.libretexts.org/Bookshelves/Anatomy_and_Physiology/Anatomy_and_Physiology_(Boundless)/22%3A_Digestive_System/22.05%3A_Layers_of_the_Alimentary_Canal/22.5C%3A_Muscularis |access-date=2024-02-09 |website=Medicine LibreTexts |language=en}}</ref> The presence of the inner oblique layer is distinct from other parts of the gastrointestinal tract, which do not possess this layer.<ref>{{Cite web|title=SIU SOM Histology GI|url=http://www.siumed.edu/~dking2/erg/stomach.htm|access-date=2021-01-09|website=www.siumed.edu|archive-date=2021-01-11|archive-url=https://web.archive.org/web/20210111015056/http://www.siumed.edu/~dking2/erg/stomach.htm|url-status=dead}}</ref> The stomach contains the thickest muscular layer consisting of three layers, thus maximum peristalsis occurs here.
* The ''inner oblique layer:'' This layer is responsible for creating the motion that churns and physically breaks down the food. It is the only layer of the three which is not seen in other parts of the [[digestive system]]. The antrum has thicker skin cells in its walls and performs more forceful contractions than the fundus.
* The ''middle circular layer:'' At this layer, the [[pylorus]] is surrounded by a thick circular muscular wall, which is normally tonically constricted, forming a functional (if not anatomically discrete) [[pyloric sphincter]], which controls the movement of [[chyme]] into the [[duodenum]]. This layer is concentric to the [[Anatomical terms of location#Axes|longitudinal axis]] of the stomach.
* The [[myenteric plexus]] (Auerbach's plexus) is found between the outer longitudinal and the middle circular layer and is responsible for the innervation of both (causing [[peristalsis]] and mixing).

The ''outer longitudinal layer'' is responsible for moving the semi-digested food towards the pylorus of the stomach through muscular shortening.

To the outside of the muscular layer lies a [[serosa]], consisting of layers of connective tissue continuous with the [[peritoneum]].

Smooth mucosa along the inside of the lesser curvature forms a passageway - the '''gastric canal'''  that fast-tracks liquids entering the stomach, to the pylorus.<ref name=Elsevier>{{citation |title=Gray's Anatomy |url=https://www.uk.elsevierhealth.com/grays-anatomy-9780702077050.html |publisher=Elsevier |edition=42nd |pages=1160–1163 |author-first=Susan |author-last=Standring}}</ref>

====Glands====
{{Main article|Gastric glands}}
[[File:Illu_stomach_layers.jpg|thumb|Diagram showing gastric pits (13) gastric glands (12) lamina propria (10) epithelium (11)]]
[[File:Histology of normal fundic mucosa.png|thumb|Histology of normal fundic mucosa. Fundic glands are simple, branched tubular glands that extend from the bottom of the gastric pits to the muscularis mucosae; the more distinctive cells are parietal cells. H&E stain.]]
[[File:Histology of normal antral mucosa.png|thumb|Histology of normal antral mucosa. Antral mucosa is formed by branched coiled tubular glands lined by secretory cells similar in appearance to the surface mucous cells. H&E stain.]]
The mucosa lining the stomach is lined with [[gastric pit]]s, which receive [[gastric juice]], secreted by between 2 and 7 [[gastric glands]].{{citation needed|date=May 2020}} Gastric juice is an acidic fluid containing [[hydrochloric acid]] and digestive enzymes.<ref>{{Cite web |date=21 August 2009 |title=How does the Stomach Work? |url=https://www.ncbi.nlm.nih.gov/books/NBK279304/#:~:text=Gastric%20juice%3A%20Acid%2C%20salts%20and%20enzymes&text=These%20glands%20make%20digestive%20enzymes,juice%20are%20made%20each%20day. |access-date=16 June 2024 |website=National Institute of Health: National Library of Medicine |publisher=Institute for Quality and Efficiency in Health Care (IQWiG).}}</ref> The glands contains a number of cells, with the function of the glands changing depending on their position within the stomach.{{citation needed|date=May 2020}}

Within the body and fundus of the stomach lie the ''fundic glands''. In general, these glands are lined by column-shaped cells that secrete a protective layer of [[mucus]] and [[bicarbonate]]. Additional cells present include [[parietal cell]]s that secrete hydrochloric acid and [[intrinsic factor]], [[Gastric chief cell|chief cell]]s that secrete [[pepsinogen]] (this is a precursor to pepsin- the highly acidic environment converts the pepsinogen to pepsin), and neuroendocrine cells that secrete [[serotonin]].<ref name=Dorland777/>{{citation needed|date=May 2020}}

Glands differ where the stomach meets the esophagus and near the pylorus.<ref>{{Cite journal|last1=Gallego-Huidobro|first1=J|last2=Pastor|first2=L M|date=April 1996|title=Histology of the mucosa of the oesophagogastric junction and the stomach in adult Rana perezi.|journal=Journal of Anatomy|volume=188|issue=Pt 2|pages=439–444|issn=0021-8782|pmc=1167580|pmid=8621343}}</ref> Near the [[gastroesophageal junction]] lie ''cardiac glands'', which primarily secrete mucus.<ref name=Dorland777>{{cite book|last1=Dorland's|title=Dorland's Illustrated Medical Dictionary|date=2012|publisher=Elsevier|isbn=978-1-4160-6257-8|page=777|edition=32nd}}</ref> They are fewer in number than the other gastric glands and are more shallowly positioned in the mucosa. There are two kinds - either simple [[tubular gland]]s with short ducts  or [[compound racemose glands|compound racemose]] resembling the [[duodenal]] [[Brunner's glands]].{{citation needed|date=October 2019}} Near the pylorus lie ''pyloric glands'' located in the antrum of the pylorus. They secrete mucus, as well as [[gastrin]] produced by their [[G cells]].<ref>{{cite book|last1=Dorland's|title=Dorland's Illustrated Medical Dictionary|date=2012|publisher=Elsevier|isbn=978-1-4160-6257-8|page=762|edition=32nd}}</ref>{{citation needed|date=May 2020}}

=== Gene and protein expression ===
{{Further |Bioinformatics#Gene and protein expression}}
About 20,000 [[protein-coding genes]] are expressed in human cells and nearly 70% of these genes are expressed in the normal stomach.<ref>{{Cite web|url=https://www.proteinatlas.org/humanproteome/stomach|title=The human proteome in stomach - The Human Protein Atlas|website=www.proteinatlas.org|access-date=2017-09-25}}</ref><ref>{{Cite journal|last1=Uhlén|first1=Mathias|last2=Fagerberg|first2=Linn|last3=Hallström|first3=Björn M.|last4=Lindskog|first4=Cecilia|last5=Oksvold|first5=Per|last6=Mardinoglu|first6=Adil|last7=Sivertsson|first7=Åsa|last8=Kampf|first8=Caroline|last9=Sjöstedt|first9=Evelina|date=2015-01-23|title=Tissue-based map of the human proteome|journal=Science|language=en|volume=347|issue=6220|pages=1260419|doi=10.1126/science.1260419|issn=0036-8075|pmid=25613900|s2cid=802377}}</ref> Just over 150 of these genes are more specifically expressed in the stomach compared to other organs, with only some 20 genes being highly specific. The corresponding specific proteins expressed in stomach are mainly involved in creating a suitable environment for handling the digestion of food for uptake of nutrients. Highly stomach-specific proteins include [[gastrokine-1]] expressed in the mucosa; [[pepsinogen]] and [[gastric lipase]], expressed in [[gastric chief cell]]s; and a gastric [[Hydrogen potassium ATPase|ATPase]] and [[gastric intrinsic factor]], expressed in [[parietal cell]]s.<ref>{{Cite journal|last1=Gremel|first1=Gabriela|last2=Wanders|first2=Alkwin|last3=Cedernaes|first3=Jonathan|last4=Fagerberg|first4=Linn|last5=Hallström|first5=Björn|last6=Edlund|first6=Karolina|last7=Sjöstedt|first7=Evelina|last8=Uhlén|first8=Mathias|last9=Pontén|first9=Fredrik|date=2015-01-01|title=The human gastrointestinal tract-specific transcriptome and proteome as defined by RNA sequencing and antibody-based profiling|journal=Journal of Gastroenterology|language=en|volume=50|issue=1|pages=46–57|doi=10.1007/s00535-014-0958-7|pmid=24789573|s2cid=21302849|issn=0944-1174}}</ref>