1. Epithelia Of The Gut Flashcards
What are the 2 main types of epithelia in the gut?
Stratified squamous
Simple columnar - which then specialise further
Where are stratified squamous epithelia found in the gut?
Oesophagus and distal anus
Where are simple columnar epithelia found in the gut?
Stomach to proximal anus
Why are stratified squamous epithelia found in oesophagus and distal anus?
Resists abrasion - physical and chemical
Is stratified squamous in the gut keratinised?
Non- keratinised as secrete mucus
What do the surface mucus cells secrete in the stomach?
Mucin by exocytosis
What do the surface mucous cells dip down to form?
Gastric pits which connect to gastric glands (in the lamina propria) by neck mucous cells
What are the characteristics of the neck mucous cells?
Smaller
Irregular shapes
What are the surface modifications in the small intestine?
Plicae circulares/valvulae conniventes (folds) Villi and microvilli Crypts (invaginations in wall) Enterocytes and goblet cells Brunner’s glands
What are present in the crypts?
Stem cells which constantly divide and replace the epithelia every 2-4 days
Enteroendocrine cells
Paneth cells
What are at the base of the crypts?
Paneth cell which secrete anti-bacterial proteins to help protect the stem cells
What are Brunner’s glands?
Glands located partly in the deep mucosa but extend into the submucosa, produce an alkaline mucoid material into the sides or bases of the crypts
Neutralise acidic chyme coming in from stomach
Do lipids usually go into lymph or blood?
Lymph
What epithelia is present in the colon?
Tall columnar epithelia (colonocytes), interspersed with larger mucus producing goblet cells
Why is mucus essential in the colon?
Mucus sustains the microbiome and forms a protective layer
