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Pada lambung terdapat kelenjar oksintik ({{lang-en|oxyntic gland}}) yang memproduksi [[hormon]] [[Ghrelin|GHS]]. Hormon lain yang disekresi antara lain adalah [[somatostatin|GHIH]].
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==Development==
In early [[human embryogenesis]], the ventral part of the embryo abuts the [[yolk sac]]. During the second week of development, as the embryo grows, it begins to surround parts of the sac. The enveloped portions form the basis for the adult gastrointestinal tract.<ref name=LARSEN2009 /> The sac is surrounded by a network of [[vitelline arteries]]. Over time, these arteries consolidate into the three main arteries that supply the developing gastrointestinal tract: the [[celiac artery]], [[superior mesenteric artery]], and [[inferior mesenteric artery]]. The areas supplied by these arteries are used to define the [[midgut]], [[hindgut]] and [[foregut]].<ref name=LARSEN2009 /> The surrounded sac becomes the primitive gut. Sections of this gut begin to differentiate into the organs of the gastrointestinal tract, and the esophagus, and stomach form from the foregut.<ref name=LARSEN2009>{{cite book|author=Gary C. Schoenwolf |title=Larsen's human embryology|year=2009|publisher=Churchill Livingstone/Elsevier|location=Philadelphia|isbn=978-0-443-06811-9|chapter=Development of the Gastrointestinal Tract|edition=4th}}</ref>
==Function==
===Digestion===
{{Main article|Digestion}}
In the [[human digestive system]], a [[Bolus (digestion)|bolus]] (a small rounded mass of [[mastication|chewed up]] food) enters the stomach through the [[oesophagus]] via the [[Oesophagus#Sphincters|lower oesophageal sphincter]]. The stomach releases [[proteases]] (protein-digesting enzymes such as [[pepsin]]) and [[hydrochloric acid]], which kills or inhibits [[bacteria]] and provides the acidic [[pH]] of 2 for the proteases to work. Food is churned by the stomach through muscular contractions of the wall called [[peristalsis]] – reducing the volume of the [[Fundus (stomach)|fundus]], before looping around the fundus<ref>{{cite book |author1=Richard M. Gore |author2=Marc S. Levine. |title=Textbook of Gastrointestinal Radiology |publisher=Saunders |location=Philadelphia, PA. |year= 2007|pages= |isbn=1-4160-2332-1}}</ref> and the [[body of stomach]] as the boluses are converted into [[chyme]] (partially digested food). Chyme slowly passes through the [[pyloric sphincter]] and into the [[duodenum]] of the [[small intestine]], where the extraction of nutrients begins. Depending on the quantity and contents of the meal, the stomach will digest the food into [[chyme]] within anywhere between forty minutes and a few hours. The average human stomach can comfortably hold about a litre of food.
Gastric juice in the stomach also contains pepsinogen. Hydrochloric acid activates this inactive form of enzyme into the active form, pepsin. Pepsin breaks down proteins into polypeptides.
=== Absorption ===
Although the absorption in the human digestive system is mainly a function of the small intestine, some absorption of certain small molecules nevertheless does occur in the stomach through its lining. This includes:
* Water, if the body is dehydrated
* Medication, like [[aspirin]]
* [[Amino acids]]<ref>{{Cite book|title=Amino Acids in Animal Nutrition|edition=2nd|editor-first=J.P.F.|editor-last=D'Mello|chapter = Absorption of Amino acids and Peptides|last = Krehbiel|first = C.R.|publisher = |year = |isbn = |location = |chapter-url = http://www.fcav.unesp.br/Home/departamentos/zootecnia/lucianohauschild/085199654x_chap03.pdf|first2 = J.C.|last2 = Matthews|pages = 41–70|chapter-format = PDF}}</ref>
* 10–20% of ingested [[ethanol]] (e.g. from alcoholic beverages)<ref name=intox>{{cite web|title=Alcohol and the Human Body|url=http://www.intox.com/t-physiology.aspx|publisher=Intoximeters, Inc.|accessdate=30 July 2012}}</ref>
* Caffeine<ref>{{Cite book|title = Coffee and Health|last = Debry|first = Gérard|publisher = John Libbey Eurotext|year = 1994|isbn = 9782742000371|location = Montrouge|url = https://books.google.com/books?id=uZaaCk-8s9sC&pg=PA129|publication-place = Montrouge|access-date = 2015-04-26|format = PDF (eBook)|page = 129}}</ref>
* To a small extent water-soluble vitamins (most are absorbed in the small intestine)<!-- See page 419--><ref>{{Cite book|title = Nutritional Sciences: From Fundamentals to Food|last1=McGuire|first1=
Michelle|last2=Beerman|first2=Kathy|publisher=Cengage Learning|edition=3|url = https://books.google.com/books?id=bYAJAAAAQBAJ|isbn=1133707386|date=2012-01-01|page=419}}</ref>
The [[parietal cell]]s of the human stomach are responsible for producing [[intrinsic factor]], which is necessary for the absorption of [[vitamin B12]]. B12 is used in cellular metabolism and is necessary for the production of [[red blood cell]]s, and the functioning of the [[nervous system]].
=== Control of secretion and motility ===
The movement and the flow of chemicals into the stomach are controlled by both the [[autonomic nervous system]] and by the various [[Digestion#Digestive hormones|digestive hormones]] of the digestive system:
{| class="wikitable"
| [[Gastrin]] || The hormone ''gastrin'' causes an increase in the secretion of HCl from the parietal cells, and pepsinogen from chief cells in the stomach. It also causes increased motility in the stomach. Gastrin is released by [[G cell]]s in the stomach in response to distension of the antrum, and digestive products (especially large quantities of incompletely digested proteins). It is inhibited by a [[pH]] normally less than 4 (high acid), as well as the hormone [[somatostatin]].
|-
| [[Cholecystokinin]] || ''Cholecystokinin'' (CCK) has most effect on the [[gall bladder]], causing gall bladder contractions, but it also decreases gastric emptying and increases release of pancreatic juice which is alkaline and neutralizes the chyme. CCK is synthesized by I-cells in the mucosal epithelium of the small intestine.
|-
| [[Secretin]] || In a different and rare manner, ''secretin'', produced in the [[small intestine]], has most effects on the pancreas, but will also diminish acid secretion in the stomach.
|-
| [[Gastric inhibitory peptide]] || ''Gastric inhibitory peptide'' (GIP) decreases both gastric acid release and motility.
|-
| [[Enteroglucagon]] || ''Enteroglucagon'' decreases both gastric acid and motility.
|-
|}
Other than gastrin, these hormones all act to turn off the stomach action. This is in response to food products in the liver and gall bladder, which have not yet been absorbed. The stomach needs to push food into the small intestine only when the intestine is not busy. While the intestine is full and still digesting food, the stomach acts as storage for food.
===Stomach acid===
{{main|Gastric acid}}
[[Epidermal growth factor]] (EGF) results in cellular proliferation, differentiation, and survival.<ref name="Herbst">{{cite journal | author = Herbst RS | title = Review of epidermal growth factor receptor biology | journal = International Journal of Radiation Oncology, Biology, Physics | volume = 59 | issue = 2 Suppl | pages = 21–6 | year = 2004 | pmid = 15142631 | doi = 10.1016/j.ijrobp.2003.11.041 | url = }}</ref> EGF is a low-molecular-weight polypeptide first purified from the mouse submandibular gland, but since then found in many human tissues including the [[submandibular gland]], and the [[parotid gland]]. Salivary EGF, which seems also regulated by dietary inorganic [[iodine]], plays also an important physiological role in the maintenance of oro-oesophageal and gastric tissue integrity. The biological effects of salivary EGF include healing of oral and gastroesophageal ulcers, inhibition of gastric acid secretion, stimulation of DNA synthesis, and mucosal protection from intraluminal injurious factors such as gastric acid, bile acids, pepsin, and trypsin and from physical, chemical, and bacterial agents.<ref>{{cite journal|author = Venturi S.|author2 = Venturi M.|year = 2009|title = Iodine in evolution of salivary glands and in oral health|journal = Nutrition and Health|volume = 20|pages = 119–134|pmid = 19835108|issue = 2|doi=10.1177/026010600902000204}}</ref>
[[File:Sequence of 123-iodide total body human scintiscans.jpg|thumb|Sequence of total-body [[Scintigraphy|scintigraphies]] of a woman after intravenous injection of [[iodine-123]] demonstrating iodine uptake by the [[gastric mucosa]]]]
===Stomach as nutrition sensor===
The human stomach can "taste" [[sodium glutamate]] using glutamate receptors<ref>{{cite journal | last1 = Uematsu | first1 = A | last2 = Tsurugizawa | first2 = T | last3 = Kondoh | first3 = T | last4 = Torii | first4 = K. | year = 2009 | title = Conditioned flavor preference learning by intragastric administration of L-glutamate in rats | url = | journal = Neurosci. Lett. | volume = 451 | issue = 3| pages = 190–3 | doi = 10.1016/j.neulet.2008.12.054 | pmid = 19146916 }}</ref> and this information is passed to the [[lateral hypothalamus]] and [[limbic system]] in the [[brain]] as a [[palatability]] signal through the [[vagus nerve]].<ref>{{cite journal | last1 = Uematsu | first1 = A | last2 = Tsurugizawa | first2 = T | last3 = Uneyama | first3 = H | last4 = Torii | first4 = K. | year = 2010 | title = Brain-gut communication via vagus nerve modulates conditioned flavor preference | url = | journal = Eur J Neurosci | volume = 31 | issue = 6| pages = 1136–43 | doi = 10.1111/j.1460-9568.2010.07136.x | pmid = 20377626 }}</ref> The stomach can also sense, independently of tongue and oral taste receptors, [[glucose]],<ref name="Araujo">{{cite journal| pmid= 18367093 | doi=10.1016/j.neuron.2008.01.032| title= Food Reward in the Absence of Taste Receptor Signaling| year= 2008| last1= De Araujo| first1= Ivan E.| last2= Oliveira-Maia| first2= Albino J.| last3= Sotnikova| first3= Tatyana D.| last4= Gainetdinov| first4= Raul R.| last5= Caron| first5= Marc G.| last6= Nicolelis| first6= Miguel A.L.| last7= Simon| first7= Sidney A.| journal= Neuron| volume= 57| issue= 6| pages= 930–41}}</ref> [[carbohydrate]]s,<ref name="Perez">{{cite journal | last1 = Perez | first1 = C. | last2 = Ackroff | first2 = K. | last3 = Sclafani | first3 = A. | year = 1996 | title = Carbohydrate- and protein conditioned flavor preferences: effects of nutrient preloads | url = | journal = Physiol. Behav. | volume = 59 | issue = 3| pages = 467–474 | doi = 10.1016/0031-9384(95)02085-3 | pmid = 8700948 }}</ref> [[protein]]s,<ref name="Perez"/> and [[fat]]s.<ref>{{cite journal | last1 = Ackroff | first1 = K. | last2 = Lucas | first2 = F. | last3 = Sclafani | first3 = A. | year = 2005 | title = Flavor preference conditioning as a function of fat source | url = | journal = Physiol. Behav. | volume = 85 | issue = 4| pages = 448–460 | doi = 10.1016/j.physbeh.2005.05.006 | pmid = 15990126 }}</ref> This allows the brain to link [[nutritional]] value of foods to their tastes.<ref name="Araujo"/>
== 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|last=Uhlén|first=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|url=http://science.sciencemag.org/content/347/6220/1260419|journal=Science|language=en|volume=347|issue=6220|pages=1260419|doi=10.1126/science.1260419|issn=0036-8075|pmid=25613900}}</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 [[GKN1]], expressed in the mucosa; [[Pepsin|pepsinogen PGC]] and the [[Lipase|lipase LIPF]], expressed in [[Gastric chief cell|chief cells]]; and gastric [[ATPase|ATPase ATP4A]] and [[Gastric intrinsic factor|gastric intrinsic factor GIF]], expressed in [[parietal cell]]s.<ref>{{Cite journal|last=Gremel|first=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|url=https://link.springer.com/article/10.1007/s00535-014-0958-7|journal=Journal of Gastroenterology|language=en|volume=50|issue=1|pages=46–57|doi=10.1007/s00535-014-0958-7|issn=0944-1174}}</ref>
==Clinical significance==
[[Image:Stomach endoscopy 1.jpg|thumb|right|200px|An [[endoscopy]] of a normal stomach of a healthy 65-year-old woman.]]
=== Diseases===
{{Main article|Stomach disease}}
A [[Upper gastrointestinal series|series of radiographs]] can be used to examine the stomach for various disorders. This will often include the use of a [[Upper gastrointestinal series|swallow barium]]. Another method of examination of the stomach, is the use of an [[endoscopy|endoscope]]. A [[gastric emptying scan]] is considered the gold standard to assess gastric emptying rate.<ref>{{cite journal|last1=Masaoka|first1=Tatsuhiro|last2=Tack|first2=Jan|title=Gastroparesis: Current Concepts and Management|journal=Gut and Liver|date=30 September 2009|volume=3|issue=3|pages=166–173|doi=10.5009/gnl.2009.3.3.166|pmc=2852706}}</ref>
A large number of studies have indicated that most cases of [[peptic ulcer]]s, and [[gastritis]], in humans are caused by ''[[Helicobacter pylori]]'' infection, and an association has been seen with the development of stomach cancer.<ref name="Brown">{{cite journal|last1=Brown|first1=LM|title=Helicobacter pylori: epidemiology and routes of transmission.|journal=Epidemiologic Reviews|date=2000|volume=22|issue=2|pages=283–97|pmid=11218379}}</ref>
A [[stomach rumble]] is actually noise from the intestines.
<!-- following unclear why under "diseases": -->The stomach has to regenerate a new layer of mucus every two weeks, or else damage to the epithelium may result.
===Surgery===
In humans, many [[bariatric surgery]] procedures involve the stomach, in order to lose weight. A [[Adjustable gastric band|gastric band]] may be placed around the cardia area, which can adjust to limit intake. The [[Sleeve gastrectomy|anatomy of the stomach may be modified]], or the stomach may be [[Gastric bypass surgery|bypassed entirely]].
Surgical removal of the stomach is called a [[gastrectomy]], and removal of the cardia area is a called a '''cardiectomy'''. "Cardiectomy" is a term that is also used to describe the removal of the [[heart]].<ref>[http://dictionary.reference.com/browse/cardiectomy cardiectomy] at dictionary.reference.com</ref><ref Name="BARLOW">{{cite journal | author =Barlow, O. W. | title =The survival of the circulation in the frog web after cardiectomy | work = | journal =Journal of Pharmacology and Experimental Therapeutics, | volume = 35| issue = 1 | pages = 17–24 | year=1929 | date = | url =http://jpet.aspetjournals.org/cgi/content/abstract/35/1/17 | accessdate = February 24, 2008 }}</ref><ref Name="MELTZER">{{cite journal | title =The effect of strychnin in cardiectomized frogs with destroyed lymph hearts; a demonstration | journal =American Journal of Physiology | volume =10 | issue =2 | year =1913 | pages =xix | url =https://books.google.com/?id=pnsZI2vxfH8C&pg=RA1-PR19&dq=Cardiectomy | doi = 10.3181/00379727-10-16| last1 =Meltzer | first1 =S. J. }}</ref> A gastrectomy may be carried out because of gastric cancer or severe perforation of the stomach wall.
==History==
There were previously conflicting statements in the academic anatomy community<ref>[http://hopkins-gi.nts.jhu.edu/pages/latin/templates/index.cfm?pg=disease1&organ=1&disease=13&lang_id=1 Digestive Disease Library]. hopkins-gi.nts.jhu.edu</ref><ref>[http://www.physio.unr.edu/ICC/gallery/LES-1.htm Department of Physiology and Cell Biology]. physio.unr.edu</ref><ref>[http://emedicine.medscape.com/article/1851864-overview Esophagogastroduodenoscopy]. [[eMedicine]]</ref> over whether the cardia is part of the stomach, part of the oesophagus or a distinct entity. Modern surgical and medical textbooks have agreed that "The gastric cardia is now clearly considered to be part of the stomach."<ref name="accessmedicine.com">Barrett KE (2006) [http://www.accessmedicine.com/content.aspx?aID=2307248 "Chapter 7. Esophageal Motility"] in ''Gastrointestinal Physiology''. Lange Medical Books/McGraw-Hill. {{ISBN|0071104968}}</ref><ref>{{cite book|last1=Sugarbaker|first1=David J.|last2=Bueno|first2=Raphael|last3=Krasna|first3=Mark J.|last4=Mentzer|first4=Steven J.|last5=Zellos|first5=Lambros|others=with Marcia Williams and Ann Adams|title=Adult chest surgery|date=2009|publisher=McGraw Hill Medical|location=New York|isbn=0071434143|displayauthors=1}}</ref>
===Etymology===
The word ''stomach'' is derived from the [[Latin]] ''{{lang|la|stomachus}}'' which is derived from the [[Ancient Greek|Greek]] word ''stomachos'' ({{lang|el|στόμαχος}}), ultimately from ''stoma'' ({{lang|el|στόμα}}), "mouth".<ref>{{cite book|author=Simpson, J. A. |title=The Oxford English dictionary|date=1989|publisher=Clarendon Press|location=Oxford|isbn=9780198611868|edition=2nd|at=Stomach}}</ref> The words ''gastro-'' and ''gastric'' (meaning related to the stomach) are both derived from the Greek word ''gaster'' ({{lang|el|γαστήρ}}, meaning "belly"<ref>[http://classic.studylight.org/lex/grk/view.cgi?number=1064 gasth/r]. The New Testament Greek Lexicon</ref><ref>[http://dictionary.reference.com/browse/gaster?r=75&src=ref&ch=dic gaster]. dictionary.reference.com</ref>).<ref>{{cite book|author=Simpson, J. A. |title=The Oxford English dictionary|date=1989|publisher=Clarendon Press|location=Oxford|isbn=9780198611868|edition=2nd|at=Gastro, Gastric}}</ref>
==Other animals==
{|
|-
| [[File:Mammalian Stomachs remake.png|thumb|650px|center|Comparison of stomach glandular regions from several mammalian species. Frequency of glands may vary more smoothly between regions than is diagrammed here. Asterisk (ruminant) represents the omasum, which is absent in [[Tylopoda]] (Tylopoda also has some cardiac glands opening onto ventral [[Reticulum (anatomy)|reticulum]] and [[rumen]]<ref>{{cite book|url=https://books.google.com/books?id=gvt_qSsLobUC&pg=PA350&lpg=PA350&dq=tylopoda+omasum|title=Functional Anatomy and Physiology of Domestic Animals|author=William O. Reece|isbn=978-0-7817-4333-4|year=2005}}</ref>) Many other variations exist among the mammals.<ref>{{cite web|url=http://www.cnsweb.org/digestvertebrates/WWWEdStevensCDAnatomy.html|title=Digestive System of Vertebrates|author1=Finegan, Esther J. |author2=Stevens, C. Edward |lastauthoramp=yes }}</ref><ref>{{cite web|url=http://www.onemedicine.tuskegee.edu/DigestiveSystem/Stomach/Stomach_Ruminants.html|title=The anatomy of the digestive system|author=Khalil, Muhammad |work=onemedicine.tuskegee.edu}}</ref>]]
| style="padding-left:1em;" |
;<span style="color:#E2E200;">Yellow</span>: [[Oesophagus]]
;<span style="color:#00AD00;">Green</span>: [[Glandular epithelium]]
;<span style="color:#A700C3;">Purple</span>: [[Cardiac gland]]s
;<span style="color:#C70000;">Red</span>: [[Gastric gland]]s
;<span style="color:#247AFF;">Blue</span>: [[Pyloric gland]]s
;<span style="color:#2A2AFF;">Dark blue</span>: [[Duodenum]]
|}
Although the precise shape and size of the stomach varies widely among different vertebrates, the relative positions of the oesophageal and duodenal openings remain relatively constant. As a result, the organ always curves somewhat to the left before curving back to meet the pyloric sphincter. However, [[lamprey]]s, [[hagfish]]es, [[chimaera]]s, [[lungfish]]es, and some [[teleost]] fish have no stomach at all, with the oesophagus opening directly into the anus. These animals all consume diets that either require little storage of food, or no pre-digestion with gastric juices, or both.<ref name=VB>{{cite book |author=Romer, Alfred Sherwood|author2=Parsons, Thomas S.|year=1977 |title=The Vertebrate Body |publisher=Holt-Saunders International |location= Philadelphia, PA|pages= 345–349|isbn= 0-03-910284-X}}</ref>
The gastric lining is usually divided into two regions, an anterior portion lined by fundic glands, and a posterior with pyloric glands. Cardiac glands are unique to [[mammal]]s, and even then are absent in a number of species. The distributions of these glands vary between species, and do not always correspond with the same regions as in humans. Furthermore, in many non-human mammals, a portion of the stomach anterior to the cardiac glands is lined with epithelium essentially identical to that of the oesophagus. [[Ruminant]]s, in particular, have a complex stomach, the first three chambers of which are all lined with oesophageal mucosa.<ref name=VB/>
In [[bird]]s and [[crocodilian]]s, the stomach is divided into two regions. Anteriorly is a narrow tubular region, the [[proventriculus]], lined by fundic glands, and connecting the true stomach to the [[crop (anatomy)|crop]]. Beyond lies the powerful muscular [[gizzard]], lined by pyloric glands, and, in some species, containing stones that the animal swallows to help grind up food.<ref name=VB/>
In [[insect]]s there is also a crop. The insect stomach is called the ([[insect#Mid-gut|midgut]].
Information about the stomach in [[echinoderm]]s or [[mollusc]]s can be found under the respective articles.
-->
== Gambar tambahan ==
<gallery>
File:Greater omentum 2.jpg|Greater omentum dan lambung manusia
File:Stomach.jpg|Lambung manusia
Image:Gray532.png|Gambar lebih realistis, menunjukkan celiac artery dan cabang-cabangnya pada manusia; organ hati telah diangkat; lesser omentum dan lapisan anterior greater omentum diambil.
File:An open stomach.jpg|Otopsi lambung manusia. 2012 Instituto Nacional de Cardiología
File:Slide15ffff.JPG|Lambung manusia
File:Illu stomach2.jpg | Dinding gastrointestinal pada lambung manusia.
Image:Fundic gland polyposis0001.jpg|Gambar endoskopi [[:en:polyp (medicine)|polyposis]] kelenjar fundus manusia.
</gallery>
== Lihat pula ==
{{Commons}}
* [[Gut flora]]
* [[Gastroesophageal reflux disease]]
* [[Proton pump inhibitors]]
== Referensi ==
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