The Gastrointestinal System ( Digestive System ) Essay
The gastrointestinal system (digestive system) is the alimentary tract from the mouth to the anus with its associated glands and organs (Moore, 2016) It originates from two germ layers, the endoderm and mesoderm, and receives nerve supply by cells derived from the third germ layer, the ectoderm(van den Brink, 2007) (McLin et al., 2009)
The earliest stage of development is the ‘primordial gut’ which forms during the 4th week as the head, tail (caudal eminence) and lateral folds. Initially the primordial gut is closed at its cranial end by the oropharyngeal membrane and at its caudal end by the cloacal membrane.
Germ layers contributions
Endoderm mucosal epithelium, mucosal and submucosal glands.
Visceral Mesoderm lamina propria, muscularis mucosa, submucosal connective tissues and blood vessels, muscularis externa and adventitia.
Ectoderm submucosal and myenteric plexuses
Subdivisions of the gut tube and their derivatives
The gut tube is subdivided into three different regions: The foregut is supplied by the celiac axis and includes: the primordial pharynx and its derivatives, lower respiratory system, oesophagus, stomach, proximal duodenum, liver, biliary apparatus and pancreas
The midgut is supplied by the superior mesenteric artery and includes: duodenum distal to the opening of the bile duct, the small intestine, the caecum, appendix, ascending colon and proximal 2/3 of the transverse colon.
The hindgut is supplied by the inferior mesenteric artery…