The stomach (from ancient Greek στόμαχος, stomachos, stoma
means mouth) is a muscular, hollow organ in the gastrointestinal tract
of humans and many other animals, including several invertebrates. The
stomach has a dilated structure and functions as a vital digestive
organ. In the digestive system the stomach is involved in the second
phase of digestion, following mastication (chewing).
In humans and many other animals, the stomach is located between the
oesophagus and the small intestine. It secretes digestive enzymes and
gastric acid to aid in food digestion. The pyloric sphincter controls
the passage of partially digested food (chyme) from the stomach into
the duodenum where peristalsis takes over to move this through the
rest of the intestines.
1.2 Blood supply
1.4 Gastric glands
3.3 Control of secretion and motility
Stomach as nutrition sensor
4 Gene and protein expression
5 Clinical significance
7 Other animals
8 Additional images
9 See also
11 External links
Sections of the human stomach
In humans, the stomach lies between the oesophagus and the duodenum
(the first part of the small intestine). It is in the left upper part
of the abdominal cavity. The top of the stomach lies against the
diaphragm. Lying behind the stomach is the pancreas. A large double
fold of visceral peritoneum called the greater omentum hangs down from
the greater curvature of the stomach. Two sphincters keep the contents
of the stomach contained; the lower oesophageal sphincter (found in
the cardiac region), at the junction of the oesophagus and stomach,
and the pyloric sphincter at the junction of the stomach with the
The stomach is surrounded by parasympathetic (stimulant) and
sympathetic (inhibitor) plexuses (networks of blood vessels and nerves
in the anterior gastric, posterior, superior and inferior, celiac and
myenteric), which regulate both the secretory activity of the stomach
and the motor (motion) activity of its muscles.
In adult humans, the stomach has a relaxed, near empty volume of about
75 millilitres. Because it is a distensible organ, it normally
expands to hold about one litre of food. The stomach of a newborn
human baby will only be able to retain about 30 millilitres.
In classical anatomy, the human stomach is divided into four sections,
beginning at the gastric cardia, each of which has different cells
The cardia is where the contents of the oesophagus empty into the
stomach. 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 to columnar. Near the cardia is the
lower oesophageal sphincter.
The fundus (from Latin, "bottom") is formed by the upper curvature of
The body is the main, central region.
The pylorus (from Greek, "gatekeeper") is the lower section of the
organ that facilitates emptying the contents into the small
intestine.antrum between body and pylorus
Schematic image of the blood supply to the human stomach: left and
right gastric artery, left and right gastroepiploic artery and short
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 the short
gastric artery which arises from the splenic artery.
Micrograph showing a cross section of the human stomach wall, in the
body portion of the stomach. H&E stain.
Main article: Gastrointestinal wall
Like the other parts of the gastrointestinal tract, the human stomach
walls consist of an outer mucosa, inner submucosa, muscularis externa,
The gastric mucosa of the stomach consists of the epithelium and the
lamina propria (composed of loose connective tissue), with a thin
layer of smooth muscle called the muscularis mucosae separating it
from the submucosa beneath. The submucosa lies under the mucosa and
consists of fibrous connective tissue, separating the mucosa from the
Meissner's plexus is in this layer. The muscularis externa
lies beneath the submucosa and is unique from other organs of the
gastrointestinal tract, consisting of three layers:
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 longitudinal axis of the stomach.
Auerbach's plexus (AKA myenteric 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 bolus
towards the pylorus of the stomach through muscular shortening.
The stomach also possesses a serosa, consisting of layers of
connective tissue continuous with the peritoneum.
Main article: Gastric glands
In humans, different types of cells are found at the different layers
of the gastric glands:
Layer of stomach
Region of stomach
Isthmus of gland
Mucus gel layer
Fundic, cardiac, pyloric
Body of gland
Parietal (oxyntic) cells
Gastric acid and intrinsic factor
Base of gland
Chief (zymogenic) cells
Pepsinogen and gastric lipase
Base of gland
Enteroendocrine (APUD) cells
Hormones gastrin, histamine, endorphins, serotonin, cholecystokinin
Fundic, cardiac, pyloric
Human cardiac glands (at cardia)
Human pyloric glands (at pylorus)
Human fundic glands (at fundus)
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. 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. 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
Main article: Digestion
In the human digestive system, a bolus (a small rounded mass of chewed
up food) enters the stomach through the oesophagus via the 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, before looping around the fundus and the body of
stomach as the boluses are converted into chyme (partially digested
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 breaks down proteins into polypeptides.
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.
Water, if the body is dehydrated
Medication, like aspirin
10–20% of ingested ethanol (e.g. from alcoholic beverages)
To a small extent water-soluble vitamins (most are absorbed in the
The parietal cells 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 cells, and the functioning of the nervous
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 digestive
hormones of the digestive system:
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 cells 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 (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.
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
Gastric inhibitory peptide (GIP) decreases both gastric acid release
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.
Main article: Gastric acid
Epidermal growth factor
Epidermal growth factor (EGF) results in cellular proliferation,
differentiation, and survival. 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
Sequence of total-body scintigraphies of a woman after intravenous
injection of iodine-123 demonstrating iodine uptake by the gastric
Stomach as nutrition sensor
The human stomach can "taste" sodium glutamate using glutamate
receptors and this information is passed to the lateral
hypothalamus and limbic system in the brain as a palatability signal
through the vagus nerve. The stomach can also sense, independently
of tongue and oral taste receptors, glucose, carbohydrates,
proteins, and fats. This allows the brain to link nutritional
value of foods to their tastes.
Gene and protein expression
Further information: Bioinformatics § Gene and protein
About 20,000 protein coding genes are expressed in human cells and
nearly 70% of these genes are expressed in the normal stomach.
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; pepsinogen PGC and the
lipase LIPF, expressed in chief cells; and gastric
ATPase ATP4A and
gastric intrinsic factor GIF, expressed in parietal cells.
An endoscopy of a normal stomach of a healthy 65-year-old woman.
A series of radiographs can be used to examine the stomach for various
disorders. This will often include the use of a swallow barium.
Another method of examination of the stomach, is the use of an
endoscope. A gastric emptying scan is considered the gold standard to
assess gastric emptying rate.
A large number of studies have indicated that most cases of peptic
ulcers, and gastritis, in humans are caused by Helicobacter pylori
infection, and an association has been seen with the development of
A stomach rumble is actually noise from the intestines. The stomach
has to regenerate a new layer of mucus every two weeks, or else damage
to the epithelium may result.
In humans, many bariatric surgery procedures involve the stomach, in
order to lose weight. A gastric band may be placed around the cardia
area, which can adjust to limit intake. The anatomy of the stomach may
be modified, or the stomach may be 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. A
gastrectomy may be carried out because of gastric cancer or severe
perforation of the stomach wall.
There were previously conflicting statements in the academic anatomy
community 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."
The word stomach is derived from the
Latin stomachus which is derived
from the Greek word stomachos (στόμαχος), ultimately from
stoma (στόμα), "mouth". The words gastro- and gastric
(meaning related to the stomach) are both derived from the Greek word
gaster (γαστήρ, meaning "belly").
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 also has some cardiac glands
opening onto ventral reticulum and rumen) Many other variations
exist among the mammals.
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, lampreys, hagfishes, chimaeras,
lungfishes, 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.
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 mammals, 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. Ruminants, in
particular, have a complex stomach, the first three chambers of which
are all lined with oesophageal mucosa.
In birds and crocodilians, 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. Beyond
lies the powerful muscular gizzard, lined by pyloric glands, and, in
some species, containing stones that the animal swallows to help grind
In insects there is also a crop. The insect stomach is called the
Information about the stomach in echinoderms or molluscs can be found
under the respective articles.
Greater omentum and stomach of humans
A more realistic image, showing the celiac artery and its branches in
humans; the liver has been raised, and the lesser omentum and anterior
layer of the greater omentum removed.
An autopsy of a human stomach. 2012 Instituto Nacional de Cardiología
The gastrointestinal wall of the human stomach.
Endoscopic image of human fundic gland polyposis.
Wikimedia Commons has media related to Stomach.
Gastroesophageal reflux disease
Proton pump inhibitors
^ Diagram from cancer.gov. Work of the United States Government
^ Physiology: 6/6ch2/s6ch2_30 - Essentials of Human Physiology
Stomach at The
Anatomy Lesson by Wesley Norman (Georgetown
^ Key to way stomach expands found. BBC (3 March 2008)
^ Sherwood, Lauralee (1997). Human physiology: from cells to systems.
Belmont, CA: Wadsworth Pub. Co. ISBN 0-314-09245-5.
Anatomy photo:37:06-0103 at the SUNY Downstate Medical Center –
"Abdominal Cavity: The Stomach"
^ Brunicardi, F. Charles; Andersen, Dana K.; et al., eds. (2010).
Schwartz's principles of surgery (9th ed.). New York: McGraw-Hill,
Medical Pub. Division. ISBN 0071547703.
^ Anne M. R. Agur; Moore, Keith L. (2007). Essential Clinical Anatomy
(Point (Lippincott Williams & Wilkins)). Hagerstown, MD:
Lippincott Williams & Wilkins. ISBN 0-7817-6274-X.
OCLC 172964542. ; p. 150
^ a b c Gary C. Schoenwolf (2009). "Development of the
Gastrointestinal Tract". Larsen's human embryology (4th ed.).
Philadelphia: Churchill Livingstone/Elsevier.
^ Richard M. Gore; Marc S. Levine. (2007). Textbook of
Gastrointestinal Radiology. Philadelphia, PA.: Saunders.
^ Krehbiel, C.R.; Matthews, J.C. "Absorption of
Amino acids and
Peptides" (PDF). In D'Mello, J.P.F. Amino Acids in Animal Nutrition
(2nd ed.). pp. 41–70.
^ "Alcohol and the Human Body". Intoximeters, Inc. Retrieved 30 July
^ Debry, Gérard (1994). Coffee and Health (PDF (eBook)). Montrouge:
John Libbey Eurotext. p. 129. ISBN 9782742000371. Retrieved
^ McGuire, Michelle; Beerman, Kathy (2012-01-01). Nutritional
Sciences: From Fundamentals to Food (3 ed.). Cengage Learning.
p. 419. ISBN 1133707386.
^ Herbst RS (2004). "Review of epidermal growth factor receptor
biology". International Journal of Radiation Oncology, Biology,
Physics. 59 (2 Suppl): 21–6. doi:10.1016/j.ijrobp.2003.11.041.
^ Venturi S.; Venturi M. (2009). "
Iodine in evolution of salivary
glands and in oral health". Nutrition and Health. 20 (2): 119–134.
doi:10.1177/026010600902000204. PMID 19835108.
^ Uematsu, A; Tsurugizawa, T; Kondoh, T; Torii, K. (2009).
"Conditioned flavor preference learning by intragastric administration
of L-glutamate in rats". Neurosci. Lett. 451 (3): 190–3.
doi:10.1016/j.neulet.2008.12.054. PMID 19146916.
^ Uematsu, A; Tsurugizawa, T; Uneyama, H; Torii, K. (2010). "Brain-gut
communication via vagus nerve modulates conditioned flavor
preference". Eur J Neurosci. 31 (6): 1136–43.
doi:10.1111/j.1460-9568.2010.07136.x. PMID 20377626.
^ a b De Araujo, Ivan E.; Oliveira-Maia, Albino J.; Sotnikova, Tatyana
D.; Gainetdinov, Raul R.; Caron, Marc G.; Nicolelis, Miguel A.L.;
Simon, Sidney A. (2008). "Food Reward in the Absence of Taste Receptor
Signaling". Neuron. 57 (6): 930–41.
doi:10.1016/j.neuron.2008.01.032. PMID 18367093.
^ a b Perez, C.; Ackroff, K.; Sclafani, A. (1996). "Carbohydrate- and
protein conditioned flavor preferences: effects of nutrient preloads".
Physiol. Behav. 59 (3): 467–474. doi:10.1016/0031-9384(95)02085-3.
^ Ackroff, K.; Lucas, F.; Sclafani, A. (2005). "Flavor preference
conditioning as a function of fat source". Physiol. Behav. 85 (4):
^ "The human proteome in stomach - The Human
www.proteinatlas.org. Retrieved 2017-09-25.
^ Uhlén, Mathias; Fagerberg, Linn; Hallström, Björn M.; Lindskog,
Cecilia; Oksvold, Per; Mardinoglu, Adil; Sivertsson, Åsa; Kampf,
Caroline; Sjöstedt, Evelina (2015-01-23). "Tissue-based map of the
human proteome". Science. 347 (6220): 1260419.
doi:10.1126/science.1260419. ISSN 0036-8075.
^ Gremel, Gabriela; Wanders, Alkwin; Cedernaes, Jonathan; Fagerberg,
Linn; Hallström, Björn; Edlund, Karolina; Sjöstedt, Evelina;
Uhlén, Mathias; Pontén, Fredrik (2015-01-01). "The human
gastrointestinal tract-specific transcriptome and proteome as defined
by RNA sequencing and antibody-based profiling". Journal of
Gastroenterology. 50 (1): 46–57. doi:10.1007/s00535-014-0958-7.
^ Masaoka, Tatsuhiro; Tack, Jan (30 September 2009). "Gastroparesis:
Current Concepts and Management". Gut and Liver. 3 (3): 166–173.
doi:10.5009/gnl.2009.3.3.166. PMC 2852706 .
^ Brown, LM (2000). "Helicobacter pylori: epidemiology and routes of
transmission". Epidemiologic Reviews. 22 (2): 283–97.
doi:10.1093/oxfordjournals.epirev.a018040. PMID 11218379.
^ cardiectomy at dictionary.reference.com
^ Barlow, O. W. (1929). "The survival of the circulation in the frog
web after cardiectomy". Journal of Pharmacology and Experimental
Therapeutics. 35 (1): 17–24. Retrieved February 24, 2008.
^ Meltzer, S. J. (1913). "The effect of strychnin in cardiectomized
frogs with destroyed lymph hearts; a demonstration". American Journal
of Physiology. 10 (2): xix. doi:10.3181/00379727-10-16.
^ Digestive Disease Library. hopkins-gi.nts.jhu.edu
^ Department of Physiology and Cell Biology. physio.unr.edu
^ Esophagogastroduodenoscopy. eMedicine
^ Barrett KE (2006) "Chapter 7. Esophageal Motility" in
Gastrointestinal Physiology. Lange Medical Books/McGraw-Hill.
^ Sugarbaker, David J.; et al. (2009). Adult chest surgery. with
Marcia Williams and Ann Adams. New York: McGraw Hill Medical.
^ Simpson, J. A. (1989). The Oxford English dictionary (2nd ed.).
Oxford: Clarendon Press. Stomach. ISBN 9780198611868.
^ gasth/r. The New Testament Greek Lexicon
^ gaster. dictionary.reference.com
^ Simpson, J. A. (1989). The Oxford English dictionary (2nd ed.).
Oxford: Clarendon Press. Gastro, Gastric.
^ William O. Reece (2005). Functional
Anatomy and Physiology of
Domestic Animals. ISBN 978-0-7817-4333-4.
^ Finegan, Esther J. & Stevens, C. Edward. "Digestive System of
^ Khalil, Muhammad. "The anatomy of the digestive system".
^ a b c Romer, Alfred Sherwood; Parsons, Thomas S. (1977). The
Vertebrate Body. Philadelphia, PA: Holt-Saunders International.
pp. 345–349. ISBN 0-03-910284-X.
Look up stomach in Wiktionary, the free dictionary.
Stomach at the Human
"Stomach" article from the Encyclopedia of Nursing & Allied
Health, from enotes.com
Digestion of proteins in the stomach or tiyan
Site with details of how ruminants process food
Medical diagram of gastric blood supply
Anatomy of the gastrointestinal tract, excluding the mouth
Gastric chief cell
Major duodenal papilla
Minor duodenal papilla
Internal anal sphincter
External anal sphincter
Serosa / Adventitia