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The lower esophageal sphincter is a muscular sphincter surrounding the lower part of the esophagus. The gastroesophageal junction between the esophagus and the stomach is controlled by the lower esophageal sphincter, which remains constricted at all times other than during swallowing and vomiting to prevent the contents of the stomach from ...
Different regions of the gut tube are initiated by retinoic acid (RA) from the pharynx to the colon. This RA causes transcription factors to be expressed in different regions of the gut tube. Thus, SOX2 specifies the esophagus and stomach; PDX1 specifies the duodenum; CDXC specifies the small intestine; CDXA specifies the large intestine and ...
Upper and lower human gastrointestinal tract. 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-/; [1] 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 ...
In the most primitive gastropods, however, the stomach is a more complex structure. In these species, the hind part of the stomach, where the oesophagus enters, is chitinous, and includes a sorting region lined with cilia. [1] In all gastropods, the portion of the stomach furthest from the oesophagus, called the "style sac", is lined with cilia.
The submucosa (or tela submucosa) is a thin layer of tissue in various organs of the gastrointestinal, respiratory, and genitourinary tracts. It is the layer of dense irregular connective tissue that supports the mucosa (mucous membrane) and joins it to the muscular layer, the bulk of overlying smooth muscle (fibers running circularly within layer of longitudinal muscle).
Chewing, needing specialized teeth, is mostly a mammalian adaptation that appeared in early Synapsids, though some later herbivorous dinosaurs, since extinct, had developed chewing too. Nowadays, only mammals chew in the strict sense of the word, though some fishes have a somewhat similar behavior.
Metaplasia is an adaptation that replaces one type of epithelium with another that is more likely to be able to withstand the stresses it is faced with. It is also accompanied by a loss of endothelial function, and in some instances considered undesirable; this undesirability is underscored by the propensity for metaplastic regions to ...
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.