Lecture 23: The basic structure of the GI tract Flashcards
What is the structure and function of epithelial membranes?
Structure: Cohesive sheet of cells - layers/sheets of cells Function: - Covers/protect body surfaces - Lines cavities - Lines systems open to air - Absorption/secretion
What types of epithelium are there?
And where are they located?
Simple sqaumous = peritoneum
Simple cuboidal = salivary glands and pancreas
—-> secretory organs have cuboidal epithelium
Simple columnar = Small intestine
Stratified sqaumous = oesaphagus
What epithelium lines unicellular glands?
- mucous secreting cells
- Columnar
- Goblet shape ; usually goblet cells
What epithelium lines multicellular glands?
- Infolding epithelium with DUCTS and TUBULAR shaped
Simple gland - single duct
Simpe tubular glands = found in stomach and large intestine
Compound gland - 2 or more ducts = salivary
What are the salivay glands in the face called?
What is their function?
Parotid = serous - enzyme only Submandibular = mixed - serous and mucous Sublingual = mucous only
What are the four layers of the gut tube?
- Mucosa
- Submucosa
- Muscularis
- Adventitia
What makes up the mucosa layer?
- Epithelium
- Lamina propia = FCT which underlines epithelium
- Muscularis mucosa
- Blood vessels and lymph vessels
What makes up the submucosa layer ?
- Glands
- FCT
- Nervous tissue = submucosal plexus/Meissner’s which is controlled by the ENS which controls secretion
What makes up the muscularis layer?
- inner circular layer
- outer longitudinal layer
- nervous tissue = myentric plexus which is controlled by the CNS which controls motility
What makes up the adventitia layer?
- FCT
Where is the submucosal plexus found? what does it regulate?
Where is the myenteric plexus found? what does it regulate?
Role of ENS in GI regulation
submucosal plexus - submucosa = regulation of secretion
myenteric plexus - mucosa = regulation of motility
