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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 ...
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 most common example of metaplasia is Barrett's esophagus, when the non-keratinizing squamous epithelium of the esophagus undergoes metaplasia to become mucinous columnar cells, ultimately protecting the esophagus from acid reflux originating in the stomach. If stress persists, metaplasia can progress to dysplasia and eventually carcinoma ...
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 ...
The radula (US: / ˈ r æ dʒ ʊ l ə /; pl.: radulae or radulas) [1] is an anatomical structure used by mollusks for feeding, sometimes compared to a tongue. [2] It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food enters the esophagus.
The human gastrointestinal tract consists of the esophagus, stomach, and intestines, and is divided into the upper and lower gastrointestinal tracts. [3] The GI tract includes all structures between the mouth and the anus , [ 4 ] forming a continuous passageway that includes the main organs of digestion, namely, the stomach , small intestine ...
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.