Lecture 23: GI histology I Flashcards
Difference b/w cheek and lip epithelium
Cheek has abundant elastic fibers in submucosa
What forms the enamel organ
Ectoderm
What forms dental papilla, what does the dental papilla form
Neural crest and mesoderm
Dental papilla forms dentin, cementum and pulp
Tooth formation- epithelial bud becomes the
Enamel organ
Tooth formation- enamel organ caps the
Dental pipilla
Odontoblasts do what
Form the dentin matrix
Ameloblasts do what
Form enamel
Cementum and dental sac
Cells of dental sac differentiate into cementoblasts which deposit cementum onto the previously secreted dentin
Periodontal membrane
CT formed from dental sac
Highly metabolic
Binds cementum to bony socket
Absorbs pressures of mastication and prevents damage to alveolar bone
Sulcus terminalis
Separates the anterior two-thirds of the tongue from the posterior third
Filiform papillae
Most numerous of all papillae
Evenly distributed over entire oral upper portion
Lacks taste buds
Fungiform papillae
Relatively few in number
Interspersed singly among the parallel rows of filiform papillae
Taste buds only present on the oral surface of epithelium
Foliate papillae
Developed in lower animals, not much in humans
Circumvallate papillae
Located along sulcus terminalis as projection surrounded by a moat
Taste buds present on lateral walls
Sustenacular cells
Support cells arranged like barrel to surround the inner taste pore at the base
Taste cells
Apical microvilli with taste receptors
Basal part of cell releases neurotransmitters
Mucosa of digestive tube
Innermost layer
Stratified squamous–> simple columnar epithelium
-Lamina propria
-Muscularis mucosa
Submucosa of digestive tube
Vascularized
Contains Meissners nerve plexus (submucosal plexus)
Muscularis externa structure
Contains inner (circular) and outer (longitudinal) layers of smooth muscle Myenteric (Auerbachs) nerve plexus lies between these two layers of muscle tissue
Muscularis externa function
Regulate size of the lumen (circular layer of smooth muscle)
Regulate rhythmic movement of GI tract (longitudinal layer of smooth muscle)
Outermost layer digestive tube
Serosa- forms visceral peritoneum which covers intraperitoneal portions of abdominal organs
Adventitia- covers retroperitoneal portions of digestive system
Gut wall sympathetic innervation
Sympathetic postganglionic fibers pass through gut wall to glands and smooth muscle
Gut wall parasympathetic innervation
Preganglionic fibers synapse with postganglionic fibers in ganglia within the gut wall itself
Meissners plexus-regulates secretion, absorption etc..
Auerbachs plexus- coordinates muscular activity of gut wall
First line of defense in gut associated lymphoid tissue
IgA is the first line of defense, it is found coating the luminal surface of the mucosal epithelium
