Layers of the gut Flashcards
What sort of surface is the gut?
External surface - in contact with outside environment, tube through the body
4 layers of gut (inner to outer)
Muscosa
Submucosa
External muscle layers
Serosa
Mucosa layer made from…
Epithelial layer
Lamina propria
Muscularis mucosae
Epithelial layer of mucosa features
Selectively permeable
Facilitate transport of food
Absorption
Hormone and Mucus production
Lamina propria features
Lots of lymphoid nodules and macrophages - payers patches
Produce antibodies (mainly IgA - resistant to protease)
Protects against bacterial/viral invasion
Distribution of epithelia through gut
Stratified squamous (non keratinised) at start and end of gut (oesophagus and anus)
Simple columnar in middle - specialised
Why stratified squamous only at start and end?
Areas of high mechanical and chemical stress. ie abrasion
Muscularis mucosae layer features
Smooth muscle in different directions
Keeps epithelia in contact with gut contents
Helps keeps crypt contents dynamic
Submucosa features
Dense connective tissue
Blood vessels
Glands
Lymphoid tissue
SUBMUCOSAL PLEXUS - Meissners
Two layers of external muscle and function
Inner circular - reduces lumen size
Outer longitudinal - reduces gut length
Work together for peristalsis
What is contained between inner circular muscle and longitudinal muscle layer?
Myenteric (Auerbach’s) plexus
Serosa layer features
Blood vessels
Lymph vessels
Adipose tissue
Continuous with mesenteries
