GI tract Flashcards
what are the 3 types of oral mucosa?
- lining mucosa
- masticatory mucosa
- specialized mucosa
what does oral mucosa consist of?
- Stratified squamous epithelium.
- Lamina propria of dense connective tissue
- Submucosa of loose connective tissue
where is masticatory mucosa found?
covering the hard palate and the gingiva (gums around the teeth). The epithelium here is keratinized or parakeratinized
where is lining mucosa found?
Inside of the lips, lining the buccal surfaces, covering the soft palate and lining the floor of the mouth and the inferior surface of the tongue. The epithelium here is not keratinized
what is the epithelium of the tongue?
Anterior 2/3: Stratified squamous epithelium, thin on ventral surface, thick and with papillae on the dorsal surface.
Posterior 1/3: Covered by smooth stratified squamous epithelium which, except for the circumvallate papillae, lacks papillae but does have substantial lymphoid aggregates in the submucosa
what covers the dorsal surface of the tongue?
keratinized stratified squamous epithelium with a dense irregular connective tissue lamina propria that ties the epithelium to the underlying muscle
what are the 4 types of tongue papillae?
- Filiform
- fungiform
- foliate
- circumvallate
what are the muscles in the tongue?
- extrinsic skeletal muscles
- intrinsic skeletal muscles bundles in longitudinal, transverse and vertical planes
what is covered by stratified squamous epithelium which is generally not keratinized?
Oral cavity, oropharynx and laryngopharynx
what covers the nasal cavity and nasopharynx?
respiratory epithelium
what are the 4 major layers (starting from the lumen and going out) that make up the digestive tract from the oesophagus to the anal canal?
- Mucosa: 3 parts
- Submucosa: loose connective tissue
- Muscularis Externa: two thick layers of smooth muscle, an inner circular layer and an outer longitudinal layer
- Serosa or Adventitia: outer layer of connective tissue that either suspends the digestive tract or attaches it to other organs
what are the 3 parts of the mucosa?
a. Epithelium: sits on a basal lamina
b. Lamina Propria: loose connective tissue
c. Muscularis Mucosae: thin layer of smooth muscle
what is the gastro-oesophageal junction?
Abrupt transition from stratified squamous epithelium of oesophagus to the simple columnar epithelium of the cardia of the stomach
what lines gastric pits?
mucous cells
what is a chief cell?
digestive enzyme secreting cell
what is parietal cell?
hydrochloric acid producing. cell
what aids the churning action of the stomach?
The muscular external layer is oblique to the usual circular and longitudinal muscle layers and is located internal to the circular layer
what is the gastroduodenal junction?
There is an abrupt transition from stomach mucosa to duodenal mucosa. The inner, circular layer of smooth muscle is markedly thickened to form the pyloric sphincter
what are the cells of the small intestinal epithelium?
- enterocytes
- goblet cells
- paneth cells
- Neuroendocrine cells
- Stem cells
what does the duodenum do?
receives the acidic, partly digested semifluid material called chyme from the stomach
what happens when Brunner glands are stimulated?
stimulated by the presence of chyme they produce a thin, alkaline mucous to neutralise the chyme
what are the 3 regions of the small intestine ?
Duodenum: Contains Brunner’s glands in the submucosa.
Jejunum: Tallest villi, located on permanent circular folds of the mucosa and submucosa, the plicae circularis. Lymphoid follicles infrequent.
Ileum: Characterized by shorter villi and aggregations of lymphoid follicles called Peyer’s patches found in the submucosa and often extending into the lamina propria
what are the two principal cell types of the large intestinal epithelium?
Absorptive cells: For removal of salts and thereby water
Goblet cells: For the secretion of mucus to lubricate the colon
what is the rectoanal junctions?
There is a distinct junction between the mucosa of the rectum and the non-keratinized stratified squamous epithelium of the anal canal
what is the nervous system of the digestive tract called?
enteric nervous system
Describe the enteric nervous system.
This interconnected network of fibres has two plexuses, one in the submucosa (submucosal) and one between the muscle layers of the muscularis externa (myenteric)
what plexus controls gut motility?
myenteric plexus
what plexus controls the muscle of the muscles mucosae and also helps regulate secretion in the epithelium?
submucosal plexus
what are the variations in mucosa?
- Protective: non-keratinized stratified squamous epithelium
- Secretory: simple columnar epithelium with extensive tubular glands
- Absorptive: simple columnar epithelium with villi & tubular glands
- Protective & absorptive: simple columnar epithelium with tubular glands
