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105-406: The stomach is located between the esophagus and the small intestine . The pyloric sphincter controls the passage of partially digested food ( chyme ) from the stomach into the duodenum , the first and shortest part of the small intestine, where peristalsis takes over to move this through the rest of the intestines. In the human digestive system , the stomach lies between the esophagus and

210-474: A biopsy may be taken. If cancer of the esophagus is being investigated, other methods, including a CT scan , may also be used. The word esophagus ( British English : oesophagus ), comes from the Greek : οἰσοφάγος ( oisophagos ) meaning gullet . It derives from two roots (eosin) to carry and ( phagos ) to eat. The use of the word oesophagus, has been documented in anatomical literature since at least

315-533: A bolus of food to enter. Peristaltic contractions of the esophageal muscle push the food down the esophagus. These rhythmic contractions occur both as a reflex response to food that is in the mouth, and also as a response to the sensation of food within the esophagus itself. Along with peristalsis, the lower esophageal sphincter relaxes. The stomach produces gastric acid , a strongly acidic mixture consisting of hydrochloric acid (HCl) and potassium and sodium salts to enable food digestion . Constriction of

420-399: 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 . Meissner's plexus is in this layer interior to the oblique muscle layer. 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

525-462: A mucous membrane consisting of a tough stratified squamous epithelium without keratin , a smooth lamina propria , and a muscularis mucosae . The epithelium of the esophagus has a relatively rapid turnover and serves a protective function against the abrasive effects of food. In many animals, the epithelium contains a layer of keratin, representing a coarser diet. There are two types of glands, with mucus-secreting esophageal glands being found in

630-439: A whale , which generally measures less than 10 cm (4 in) in diameter, although in larger baleen whales it may be up to 25 cm (10 in) when fully distended. A structure with the same name is often found in invertebrates, including molluscs and arthropods , connecting the oral cavity with the stomach. In terms of the digestive system of snails and slugs , the mouth opens into an esophagus, which connects to

735-423: A corrosive substance, or a solid object is swallowed, it is most likely to lodge and damage one of these four points. These constrictions arise from particular structures that compress the esophagus. These constrictions are: The esophagus is surrounded at the top and bottom by two muscular rings, known respectively as the upper esophageal sphincter and the lower esophageal sphincter. These sphincters act to close

840-409: A high triglyceride content remain in the stomach the longest. Since enzymes in the small intestine digest fats slowly, food can stay in the stomach for 6 hours or longer when the duodenum is processing fatty chyme. However, this is still a fraction of the 24 to 72 hours that full digestion typically takes from start to finish. Although the absorption in the human digestive system is mainly a function of

945-410: A layer of loose connective tissue . It is mostly of endodermal origin and is continuous with the skin at body openings such as the eyes , eyelids , ears , inside the nose , inside the mouth , lips , the genital areas , the urethral opening and the anus . Some mucous membranes secrete mucus , a thick protective fluid. The function of the membrane is to stop pathogens and dirt from entering

1050-461: A lot. A bleeding varix may cause a person to vomit blood , or suffer shock . To deal with a ruptured varix, a band may be placed around the bleeding blood vessel, or a small amount of a clotting agent may be injected near the bleed. A surgeon may also try to use a small inflatable balloon to apply pressure to stop the wound. IV fluids and blood products may be given in order to prevent hypovolemia from excess blood loss. Several disorders affect

1155-421: A person has had reflux for many years. Other strictures may include esophageal webs (which can also be congenital) and damage to the esophagus by radiotherapy, corrosive ingestion, or eosinophilic esophagitis. A Schatzki ring is fibrosis at the gastroesophageal junction. Strictures may also develop in chronic anemia , and Plummer-Vinson syndrome. Two of the most common congenital malformations affecting

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1260-567: A person is immunocompromised . As of 2021 the causes of some forms of esophagitis, such as eosinophilic esophagitis , are not well-characterized, but may include Th2 -mediated atopies or genetic factors. There appear to be correlations between eosinophilic esophagitis, asthma (itself with an eosinophilic component), eczema , and allergic rhinitis , though it is not clear whether these conditions contribute to eosinophilic esophagitis or vice versa, or if they are symptoms of mutual underlying factors. Esophagitis can cause painful swallowing and

1365-430: A process called gastric emptying , rhythmic mixing waves force about 3 mL of chyme at a time through the pyloric sphincter and into the duodenum. Release of a greater amount of chyme at one time would overwhelm the capacity of the small intestine to handle it. The rest of the chyme is pushed back into the body of the stomach, where it continues mixing. This process is repeated when the next mixing waves force more chyme into

1470-505: A sphincter but does not have a distinct thickening like other sphincters. The upper esophageal sphincter surrounds the upper part of the esophagus. It consists of skeletal muscle but is not under voluntary control . Opening of the upper esophageal sphincter is triggered by the swallowing reflex . The primary muscle of the upper esophageal sphincter is the cricopharyngeal part of the inferior pharyngeal constrictor . The lower esophageal sphincter, or gastroesophageal sphincter, surrounds

1575-441: 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 up food. In insects , there is also a crop. The insect stomach is called the midgut . Information about the stomach in echinoderms or molluscs can be found under

1680-400: Is a precursor to pepsin- the highly acidic environment converts the pepsinogen to pepsin), and neuroendocrine cells that secrete serotonin . Glands differ where the stomach meets the esophagus and near the pylorus. Near the gastroesophageal junction lie cardiac glands , which primarily secrete mucus. They are fewer in number than the other gastric glands and are more shallowly positioned in

1785-447: Is a spasm of the esophagus that can be one cause of chest pain. Such referred pain to the wall of the upper chest is quite common in esophageal conditions. Sclerosis of the esophagus, such as with systemic sclerosis or in CREST syndrome may cause hardening of the walls of the esophagus and interfere with peristalsis. Esophageal strictures are usually benign and typically develop after

1890-514: 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. Fundoplication is stomach surgery in which the fundus is wrapped around the lower esophagus and stitched into place. It is used to treat gastroesophageal reflux disease (GERD) . The word stomach is derived from Greek stomachos ( στόμαχος ), ultimately from stoma ( στόμα ) 'mouth'. Gastro- and gastric (meaning 'related to

1995-445: Is able to digest enough food and water. As of 2014 , the prognosis for esophageal cancer is still poor, so palliative therapy may also be a focus of treatment. Esophageal varices are swollen twisted branches of the azygous vein in the lower third of the esophagus. These blood vessels anastomose (join up) with those of the portal vein when portal hypertension develops. These blood vessels are engorged more than normal, and in

2100-540: Is an acidic fluid containing hydrochloric acid and digestive enzymes. The glands contains a number of cells, with the function of the glands changing depending on their position within the stomach. 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 cells that secrete hydrochloric acid and intrinsic factor , chief cells that secrete pepsinogen (this

2205-525: Is from the celiac trunk , and venous drainage is by the portal venous system . Lymph from these organs is drained to the prevertebral celiac nodes at the origin of the celiac artery from the aorta . In the human digestive system , a bolus (a small rounded mass of chewed up food) enters the stomach through the esophagus via the lower esophageal sphincter . The stomach releases proteases (protein-digesting enzymes such as pepsin ), and hydrochloric acid , which kills or inhibits bacteria and provides

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2310-446: 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. Epidermal growth factor (EGF) results in cellular proliferation, differentiation, and survival. EGF is a low-molecular-weight polypeptide first purified from

2415-400: Is initially striated but then becomes smooth muscle in the caudal third or so. In canines and ruminants , however, it is entirely striated to allow regurgitation to feed young (canines) or regurgitation to chew cud (ruminants). It is entirely smooth muscle in amphibians, reptiles and birds. Contrary to popular belief, an adult human body would not be able to pass through the esophagus of

2520-424: Is most common in developed countries in those with Barrett's esophagus, and occurs in the cuboidal cells. In its early stages, esophageal cancer may not have any symptoms at all. When severe, esophageal cancer may eventually cause obstruction of the esophagus, making swallowing of any solid foods very difficult and causing weight loss. The progress of the cancer is staged using a system that measures how far into

2625-428: 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. This syndrome defines the association between thyroid disease and chronic gastritis, which

2730-407: 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 arteries , which arise from

2835-459: Is thought to be one of the main contributors to the development of esophageal cancer . There are two main types of cancer of the esophagus . Squamous cell carcinoma is a carcinoma that can occur in the squamous cells lining the esophagus. This type is much more common in China and Iran . The other main type is an adenocarcinoma that occurs in the glands or columnar tissue of the esophagus. This

2940-432: Is usually treated by managing the cause of the esophagitis - such as managing reflux or treating infection. Prolonged esophagitis, particularly from gastric reflux, is one factor thought to play a role in the development of Barrett's esophagus . In this condition, there is metaplasia of the lining of the lower esophagus, which changes from stratified squamous epithelia to simple columnar epithelia . Barrett's esophagus

3045-430: Is visible as a zig-zag line. Most of the muscle is smooth muscle although striated muscle predominates in its upper third. It has two muscular rings or sphincters in its wall, one at the top and one at the bottom. The lower sphincter helps to prevent reflux of acidic stomach content. The esophagus has a rich blood supply and venous drainage. Its smooth muscle is innervated by involuntary nerves ( sympathetic nerves via

3150-407: The duodenum (the first part of the small intestine ). It is in the left upper quadrant 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;

3255-428: The erector spinae muscles and the vertebral column . The lower esophagus lies behind the heart and curves in front of the thoracic aorta . From the bifurcation of the trachea downwards, the esophagus passes behind the right pulmonary artery , left main bronchus , and left atrium . At this point, it passes through the diaphragm. The thoracic duct , which drains the majority of the body's lymph , passes behind

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3360-424: The heart or limbs . The other cases occur singly. An X-ray of swallowed barium may be used to reveal the size and shape of the esophagus, and the presence of any masses. The esophagus may also be imaged using a flexible camera inserted into the esophagus, in a procedure called an endoscopy . If an endoscopy is used on the stomach, the camera will also have to pass through the esophagus. During an endoscopy,

3465-442: The 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 (inhibitor) and sympathetic (stimulant) plexuses (networks of blood vessels and nerves in the anterior gastric, posterior , superior and inferior , celiac and myenteric), which regulate both

3570-437: 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, such as the esophagus, stomach , and intestines . The esophagus develops as part of the foregut tube. The innervation of the esophagus develops from the pharyngeal arches . Food is ingested through the mouth and when swallowed passes first into

3675-414: The nervous system . Chyme from the stomach is slowly released into the duodenum through coordinated peristalsis and opening of the pyloric sphincter. 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: Other than gastrin, these hormones all act to turn off the stomach action. This

3780-449: The nucleus ambiguus , whereas fibers that supply the smooth muscle and lower esophageal sphincter have bodies situated in the dorsal motor nucleus . The vagus nerve plays the primary role in initiating peristalsis . The sympathetic trunk has a sympathetic function. It may enhance the function of the vagus nerve, increasing peristalsis and glandular activity, and causing sphincter contraction. In addition, sympathetic activation may relax

3885-414: The pharynx and then into the esophagus. The esophagus is thus one of the first components of the digestive system and the gastrointestinal tract . After food passes through the esophagus, it enters the stomach. When food is being swallowed, the epiglottis moves backward to cover the larynx , preventing food from entering the trachea . At the same time, the upper esophageal sphincter relaxes, allowing

3990-529: The pharynx to the stomach . The esophagus is a fibromuscular tube, about 25 cm (10 in) long in adults, that travels behind the trachea and heart , passes through the diaphragm , and empties into the uppermost region of the stomach . During swallowing, the epiglottis tilts backwards to prevent food from going down the larynx and lungs. The word oesophagus is from Ancient Greek οἰσοφάγος (oisophágos), from οἴσω (oísō), future form of φέρω (phérō, "I carry") + ἔφαγον (éphagon, "I ate"). The wall of

4095-454: The submucosa and esophageal cardiac glands, similar to cardiac glands of the stomach, located in the lamina propria and most frequent in the terminal part of the organ. The mucus from the glands gives a good protection to the lining. The submucosa also contains the submucosal plexus , a network of nerve cells that is part of the enteric nervous system . The muscular layer of the esophagus has two types of muscle. The upper third of

4200-731: The sympathetic trunk and parasympathetic nerves via the vagus nerve ) and in addition voluntary nerves ( lower motor neurons ) which are carried in the vagus nerve to innervate its striated muscle. The esophagus passes through the thoracic cavity into the diaphragm into the stomach. The esophagus may be affected by gastric reflux , cancer , prominent dilated blood vessels called varices that can bleed heavily, tears , constrictions, and disorders of motility. Diseases may cause difficulty swallowing ( dysphagia ), painful swallowing ( odynophagia ), chest pain , or cause no symptoms at all. Clinical investigations include X-rays when swallowing barium sulfate , endoscopy , and CT scans . Surgically,

4305-525: The yolk sac . During the second week of embryological 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

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4410-408: The acidic pH of 2 for the proteases to work. Food is churned by the stomach through peristaltic muscular contractions of the wall – reducing the volume of the bolus, before looping around the fundus 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

4515-443: The basis for the adult gastrointestinal tract. The sac is surrounded by a network of vitelline arteries and veins . 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 foregut , midgut , and hindgut . The surrounded sac becomes

4620-417: The body and to prevent bodily tissues from becoming dehydrated. The mucosa is composed of one or more layers of epithelial cells that secrete mucus , and an underlying lamina propria of loose connective tissue . The type of cells and type of mucus secreted vary from organ to organ and each can differ along a given tract. Mucous membranes line the digestive, respiratory and reproductive tracts and are

4725-408: The cardia followed by the fundus, the body and the pylorus. 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 esophageal sphincter. The stomach bed refers to the structures upon which the stomach rests in mammals. These include the tail of

4830-442: The cardiac sphincter, connects the stomach to the esophagus. This sphincter is very well developed in horses. This and the oblique angle at which the esophagus connects to the stomach explains why horses cannot vomit . The esophagus is also the area of the digestive tract where horses may have the condition known as choke . The esophagus of snakes is remarkable for the distension it undergoes when swallowing prey. In most fish,

4935-419: The course of the esophagus. The upper and middle parts of the esophagus drain into the azygos and hemiazygos veins , and blood from the lower part drains into the left gastric vein . All these veins drain into the superior vena cava , with the exception of the left gastric vein, which is a branch of the portal vein . Lymphatically, the upper third of the esophagus drains into the deep cervical lymph nodes ,

5040-417: The deeper red of the gastric mucosa, and the mucosal transition can be seen as an irregular zig-zag line, which is often called the z-line. Histological examination reveals abrupt transition between the stratified squamous epithelium of the esophagus and the simple columnar epithelium of the stomach . Normally, the cardia of the stomach is immediately distal to the z-line and the z-line coincides with

5145-438: The digesting and readsorbing ability, and lastly, similar ability to form iodotyrosines by peroxidase activity, where iodide acts as an electron donor in the presence of H 2 O 2 . In the following years, many researchers published reviews about this syndrome. A series of radiographs can be used to examine the stomach for various disorders. This will often include the use of a barium swallow . Another method of examination of

5250-463: The dorsal mesentery thins and forms the greater omentum , which is attached to the greater curvature of the stomach. The ventral mesentery forms the lesser omentum, and is attached to the developing liver . In the adult, these connective structures of omentum and mesentery form the peritoneum , and act as an insulating and protective layer while also supplying organs with blood and lymph vessels as well as nerves. Arterial supply to all these structures

5355-410: The duodenum. Gastric emptying is regulated by both the stomach and the duodenum. The presence of chyme in the duodenum activates receptors that inhibit gastric secretion. This prevents additional chyme from being released by the stomach before the duodenum is ready to process it. The fundus stores both undigested food and gases that are released during the process of chemical digestion. Food may sit in

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5460-424: The esophageal mucosa. The esophagus is innervated by the vagus nerve and the cervical and thoracic sympathetic trunk . The vagus nerve has a parasympathetic function, supplying the muscles of the esophagus and stimulating glandular contraction. Two sets of nerve fibers travel in the vagus nerve to supply the muscles. The upper striated muscle, and upper esophageal sphincter, are supplied by neurons with bodies in

5565-407: The esophageal wall the cancer has invaded, how many lymph nodes are affected, and whether there are any metastases in different parts of the body. Esophageal cancer is often managed with radiotherapy, chemotherapy, and may also be managed by partial surgical removal of the esophagus . Inserting a stent into the esophagus, or inserting a nasogastric tube , may also be used to ensure that a person

5670-416: The esophagus and the upper esophageal sphincter receive blood from the inferior thyroid artery , the parts of the esophagus in the thorax from the bronchial arteries and branches directly from the thoracic aorta , and the lower parts of the esophagus and the lower esophageal sphincter receive blood from the left gastric artery and the left inferior phrenic artery . The venous drainage also differs along

5775-414: The esophagus are an esophageal atresia where the esophagus ends in a blind sac instead of connecting to the stomach; and an esophageal fistula – an abnormal connection between the esophagus and the trachea. Both of these conditions usually occur together. These are found in about 1 in 3500 births. Half of these cases may be part of a syndrome where other abnormalities are also present, particularly of

5880-443: The esophagus are described here. For a more complete list, see esophageal disease . Inflammation of the esophagus is known as esophagitis . Reflux of gastric acids from the stomach, infection, substances ingested (for example, corrosives ), some medications (such as bisphosphonates ), and food allergies can all lead to esophagitis. Esophageal candidiasis is an infection of the yeast Candida albicans that may occur when

5985-429: The esophagus contains striated muscle , the lower third contains smooth muscle , and the middle third contains a mixture of both. Muscle is arranged in two layers: one in which the muscle fibers run longitudinal to the esophagus, and the other in which the fibers encircle the esophagus. These are separated by the myenteric plexus , a tangled network of nerve fibers involved in the secretion of mucus and in peristalsis of

6090-415: The esophagus focused in the neck, and was conducted in dogs by Theodore Billroth in 1871. In 1877 Czerny carried out surgery in people. By 1908, an operation had been performed by Voeckler to remove the esophagus, and in 1933 the first surgical removal of parts of the lower esophagus, (to control esophageal cancer ), had been conducted. The Nissen fundoplication , in which the stomach is wrapped around

6195-413: The esophagus from the lumen outwards consists of mucosa , submucosa (connective tissue), layers of muscle fibers between layers of fibrous tissue , and an outer layer of connective tissue. The mucosa is a stratified squamous epithelium of around three layers of squamous cells, which contrasts to the single layer of columnar cells of the stomach. The transition between these two types of epithelium

6300-469: The esophagus generally starts around the level of the sixth cervical vertebra behind the cricoid cartilage of the trachea , enters the diaphragm at about the level of the tenth thoracic vertebra , and ends at the cardia of the stomach, at the level of the eleventh thoracic vertebra . The esophagus is usually about 25 cm (10 in) in length. Many blood vessels serve the esophagus, with blood supply varying along its course. The upper parts of

6405-408: The esophagus is difficult to access in part due to its position between critical organs and directly between the sternum and spinal column. The esophagus is one of the upper parts of the digestive system . There are taste buds on its upper part. It begins at the back of the mouth, passing downward through the rear part of the mediastinum , through the diaphragm , and into the stomach. In humans,

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6510-436: The esophagus is extremely short, primarily due to the length of the pharynx (which is associated with the gills ). However, some fish, including lampreys , chimaeras , and lungfish , have no true stomach, so that the esophagus effectively runs from the pharynx directly to the intestine , and is therefore somewhat longer. In many vertebrates, the esophagus is lined by stratified squamous epithelium without glands. In fish,

6615-411: The esophagus is often lined with columnar epithelium , and in amphibians , sharks and rays , the esophageal epithelium is ciliated , helping to wash food along, in addition to the action of muscular peristalsis. In addition, in the bat Plecotus auritus , fish and some amphibians, glands secreting pepsinogen or hydrochloric acid have been found. The muscle of the esophagus in many mammals

6720-496: The esophagus opening directly into the intestine. These animals all consume diets that require little storage of food, no predigestion with gastric juices, or both. The gastric lining is usually divided into two regions, an anterior portion lined by fundic glands and a posterior portion lined 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

6825-420: The esophagus when food is not being swallowed. The upper esophageal sphincter is an anatomical sphincter, which is formed by the lower portion of the inferior pharyngeal constrictor, also known as the cricopharyngeal sphincter due to its relation with cricoid cartilage of the larynx anteriorly. However, the lower esophageal sphincter is not an anatomical but rather a functional sphincter, meaning that it acts as

6930-472: The esophagus with less than 50 genes being highly specific. The corresponding esophagus-specific proteins are mainly involved in squamous differentiation such as keratins KRT13 , KRT4 and KRT6C . Other specific proteins that help lubricate the inner surface of esophagus are mucins such as MUC21 and MUC22. Many genes with elevated expression are also shared with skin and other organs that are composed of squamous epithelia . The main conditions affecting

7035-405: The esophagus, curving from lying behind the esophagus on the right in the lower part of the esophagus, to lying behind the esophagus on the left in the upper esophagus. The esophagus also lies in front of parts of the hemiazygos veins and the intercostal veins on the right side. The vagus nerve divides and covers the esophagus in a plexus . The esophagus has four points of constriction. When

7140-434: The extensive venous plexus that exists between this vein and other veins, if portal hypertension occurs, the direction of blood drainage in this vein may reverse, with blood draining from the portal venous system, through the plexus. Veins in the plexus may engorge and lead to varices. Esophageal varices often do not have symptoms until they rupture. A ruptured varix is considered a medical emergency because varices can bleed

7245-429: The extraction of nutrients begins. 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 . Within a few moments after food enters the stomach, mixing waves begin to occur at intervals of approximately 20 seconds. A mixing wave is a unique type of peristalsis that mixes and softens

7350-418: The food with gastric juices to create chyme. The initial mixing waves are relatively gentle, but these are followed by more intense waves, starting at the body of the stomach and increasing in force as they reach the pylorus. The pylorus, which holds around 30 mL of chyme, acts as a filter, permitting only liquids and small food particles to pass through the mostly, but not fully, closed pyloric sphincter . In

7455-456: The front of the esophagus in all carnivorous snails and slugs. In the freshwater snail species Tarebia granifera , the brood pouch is above the esophagus. In the cephalopods , the brain often surrounds the esophagus. Mucosa A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying

7560-501: The fundus of the stomach for a while before being mixed with the chyme. While the food is in the fundus, the digestive activities of salivary amylase continue until the food begins mixing with the acidic chyme. Ultimately, mixing waves incorporate this food with the chyme, the acidity of which inactivates salivary amylase and activates lingual lipase . Lingual lipase then begins breaking down triglycerides into free fatty acids, and mono- and diglycerides. The breakdown of protein begins in

7665-404: The inner oblique, middle circular, and outer longitudinal layers. The presence of the inner oblique layer is distinct from other parts of the gastrointestinal tract, which do not possess this layer. The stomach contains the thickest muscular layer consisting of three layers, thus maximum peristalsis occurs here. The outer longitudinal layer is responsible for moving the semi-digested food towards

7770-424: The intestines. 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"

7875-402: The lower esophageal sphincter to stimulate its function and control reflux , was first conducted by Rudolph Nissen in 1955. In tetrapods , the pharynx is much shorter, and the esophagus correspondingly longer, than in fish. In the majority of vertebrates, the esophagus is simply a connecting tube, but in some birds , which regurgitate components to feed their young, it is extended towards

7980-422: The lower end to form a crop for storing food before it enters the true stomach. In ruminants , animals with four chambered stomachs, a groove called the sulcus reticuli is often found in the esophagus, allowing milk to drain directly into the hind stomach, the abomasum . In the horse the esophagus is about 1.2 to 1.5 m (4 to 5 ft) in length, and carries food to the stomach. A muscular ring, called

8085-420: The lower part of the esophagus at the junction between the esophagus and the stomach. It is also called the cardiac sphincter or cardioesophageal sphincter, named from the adjacent part of the stomach, the cardia . Dysfunction of the gastroesophageal sphincter causes gastroesophageal reflux , which causes heartburn , and, if it happens often enough, can lead to gastroesophageal reflux disease , with damage of

8190-467: The majority of mucous membranes are of endodermal origin. Exceptions include the palate , cheeks , floor of the mouth , gums , lips and the portion of the anal canal below the pectinate line , which are all ectodermal in origin. One of its functions is to keep the tissue moist (for example in the respiratory tract, including the mouth and nose). It also plays a role in absorbing and transforming nutrients . Mucous membranes also protect

8295-421: The middle into the superior and posterior mediastinal lymph nodes, and the lower esophagus into the gastric and celiac lymph nodes . This is similar to the lymphatic drainage of the abdominal structures that arise from the foregut , which all drain into the celiac nodes. The upper esophagus lies at the back of the mediastinum behind the trachea , adjoining along the tracheoesophageal stripe , and in front of

8400-477: The motility of food as it travels down the esophagus. This can cause difficult swallowing, called dysphagia , or painful swallowing, called odynophagia . Achalasia refers to a failure of the lower esophageal sphincter to relax properly, and generally develops later in life. This leads to progressive enlargement of the esophagus, and possibly eventual megaesophagus . A nutcracker esophagus refers to swallowing that can be extremely painful. Diffuse esophageal spasm

8505-736: The mouse submandibular gland, but since then found in many human tissues including the submandibular gland , and the parotid gland . Salivary EGF, which also seems to be regulated by dietary inorganic iodine , also plays an important physiological role in the maintenance of oro-esophageal 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. The human stomach has receptors responsive to sodium glutamate and this information

8610-411: The mucosa. There are two kinds - either simple tubular glands with short ducts or compound racemose resembling the duodenal Brunner's glands . 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 . About 20,000 protein-coding genes are expressed in human cells and nearly 70% of these genes are expressed in

8715-415: The mucosa; pepsinogen and gastric lipase , expressed in gastric chief cells ; and a gastric ATPase and gastric intrinsic factor , expressed in parietal cells . In the early part of the development of the human embryo , the ventral part of the embryo abuts the yolk sac . During the third week of development, as the embryo grows, it begins to surround parts of the yolk sac. The enveloped portions form

8820-428: The muscle wall and cause blood vessel constriction. Sensation along the esophagus is supplied by both nerves, with gross sensation being passed in the vagus nerve and pain passed up the sympathetic trunk. The gastroesophageal junction (also known as the esophagogastric junction) is the junction between the esophagus and the stomach, at the lower end of the esophagus. The pink color of the esophageal mucosa contrasts to

8925-409: 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 gastrokine-1 expressed in

9030-468: 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. The lesser curvature of the human stomach

9135-431: The primary barrier between the external world and the interior of the body; in an adult human the total surface area of the mucosa is about 400 square meters while the surface area of the skin is about 2 square meters. Along with providing a physical barrier, they also contain key parts of the immune system and serve as the interface between the body proper and the microbiome . Some examples include: Developmentally,

9240-432: 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. As the stomach rotates during early development, the dorsal and ventral mesentery rotate with it; this rotation produces a space anterior to the expanding stomach called the greater sac, and a space posterior to the stomach called the lesser sac. After this rotation

9345-502: 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. The mucosa lining the stomach is lined with gastric pits , which receive gastric juice , secreted by between 2 and 7 gastric glands . Gastric juice

9450-459: The respective articles. Esophagus The esophagus ( American English ), oesophagus ( British English ), or œsophagus ( archaic spelling ) ( see spelling difference ) all / iː ˈ s ɒ f ə ɡ ə s , ɪ -/ ; pl. : ((o)e)(œ)sophagi or ( (o)e)(œ)sophaguses ), colloquially known also as the food pipe , food tube , or gullet , is an organ in vertebrates through which food passes, aided by peristaltic contractions , from

9555-408: 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 esophagus. Ruminants , in particular, have a complex stomach, the first three chambers of which are all lined with esophageal mucosa. In birds and crocodilians , the stomach is divided into two regions. Anteriorly

9660-471: The secretory activity of the stomach and the motor (motion) activity of its muscles. The stomach is distensible , and can normally expand to hold about one litre of food. 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, although volumes of up to 15 litres have been observed in extreme circumstances. The human stomach can be divided into four sections, beginning at

9765-449: The small intestine, some absorption of certain small molecules nevertheless does occur in the stomach through its lining. This includes: 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

9870-404: The smooth muscle of the esophagus. The outermost layer of the esophagus is the adventitia in most of its length, with the abdominal part being covered in serosa . This makes it distinct from many other structures in the gastrointestinal tract that only have a serosa. In early embryogenesis , the esophagus develops from the endodermal primitive gut tube . The ventral part of the embryo abuts

9975-441: The splenic artery. The two sets of gastric lymph nodes drain the stomach. 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 . 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 ,

10080-432: The stomach through the actions of hydrochloric acid, and the enzyme pepsin . The stomach can also produce gastric lipase , which can help digesting fat. The contents of the stomach are completely emptied into the duodenum within two to four hours after the meal is eaten. Different types of food take different amounts of time to process. Foods heavy in carbohydrates empty fastest, followed by high-protein foods. Meals with

10185-481: The stomach') are both derived from Greek gaster ( γαστήρ ) 'belly'. Although the precise shape and size of the stomach varies widely among different vertebrates, the relative positions of the esophageal 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

10290-412: The stomach, is the use of an endoscope . A gastric emptying study is considered the gold standard to assess the 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 stomach cancer . A stomach rumble is actually noise from

10395-415: The stomach. Because of torsion , which is the rotation of the main body of the animal during larval development, the esophagus usually passes around the stomach, and opens into its back, furthest from the mouth. In species that have undergone de-torsion, however, the esophagus may open into the anterior of the stomach, which is the reverse of the usual gastropod arrangement. There is an extensive rostrum at

10500-490: The thyroid cells, such as primitive gastroenteric cells, migrated and specialized in uptake of iodide and in storage and elaboration of iodine compounds during vertebrate evolution. In fact, the stomach and thyroid share iodine-concentrating ability and many morphological and functional similarities, such as cell polarity and apical microvilli, similar organ-specific antigens and associated autoimmune diseases, secretion of glycoproteins (thyroglobulin and mucin) and peptide hormones,

10605-502: The time of Hippocrates , who noted that "the oesophagus ... receives the greatest amount of what we consume." Its existence in other animals and its relationship with the stomach was documented by the Roman naturalist Pliny the Elder (AD23–AD79), and the peristaltic contractions of the esophagus have been documented since at least the time of Galen . The first attempt at surgery on

10710-455: The upper and lower esophageal sphincters helps to prevent reflux (backflow) of gastric contents and acid into the esophagus, protecting the esophageal mucosa. The acute angle of His and the lower crura of the diaphragm also help this sphincteric action. About 20,000 protein-coding genes are expressed in human cells and nearly 70% of these genes are expressed in the normal esophagus. Some 250 of these genes are more specifically expressed in

10815-481: The upper limit of the gastric folds of the cardia; however, when the anatomy of the mucosa is distorted in Barrett's esophagus the true gastroesophageal junction can be identified by the upper limit of the gastric folds rather than the mucosal transition. The functional location of the lower oesophageal sphincter is generally situated about 3 cm ( 1 + 1 ⁄ 4  in) below the z-line. The human esophagus has

10920-423: The worst cases may partially obstruct the esophagus. These blood vessels develop as part of a collateral circulation that occurs to drain blood from the abdomen as a result of portal hypertension , usually as a result of liver diseases such as cirrhosis . This collateral circulation occurs because the lower part of the esophagus drains into the left gastric vein, which is a branch of the portal vein. Because of

11025-417: Was first described in the 1960s. This term was coined also to indicate the presence of thyroid autoantibodies or autoimmune thyroid disease in patients with pernicious anemia, a late clinical stage of atrophic gastritis. In 1993, a more complete investigation on the stomach and thyroid was published, reporting that the thyroid is, embryogenetically and phylogenetically, derived from a primitive stomach, and that

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