Epithelia of gut Flashcards
Epithelia types in gut
Stratified squamous (oesophagus and distal anus - start and finish)
Simple columnar specialised (stomach to proximal anus - middle_
Why is stratified squamous non-keritinised?
No need to worry about water loss like with skin but needs to be squamous to resist chemical and mechanical stress and secrete mucus
Stomach epithelia
Surface mucous cells which line gastric mucosa and gastric pits
These secrete mucus and HCO3 that forms barrier to stomach acid
Basal nuclei in these columnar cells
Where are neck mucous cells found?
Where epithelium becomes lamina propria (transition zone)
Epithelia is connected to gastric glands which line lamina propria
Neck mucous cells vs surface mucous cells
Neck cells - smaller, more irregular as compressed, less vacuoles of mucin
Small intestine cells
Enterocyte - one cell thick with goblet cells between
Why enterocytes?
Transport nutrients through apical membrane and basolateral membrane where blood vessels and lymphatics lie below enterocyte
How is small intestine modified for absorption?
Plicae circularis –> villi –> microvilli (brush border) = large SA
Intestines cell structure and its progression
Goblet cells scattered between enterocytes
More and more goblet cells from duodenum –> colon
Goblet cell structure
Mucus compresses nucleus to base
Narrow base and large apical size
Function of mucus
Protects from:
Friction (lubricant)
Chemical damage (pH)
Bacterial inflammation (forms physical barrier)
Cells found within crypts of intestines
Enteroendocrine cells - deeper crypts and gastric glands
Stem cells
Paneth cells
Enteroendocrine cell function
Secrete hormones that control function of gut (eg gastrin, secretin, cholecystokinin)
Stem cell function
Constantly divide and replace epithelia barrier every 2-4 days - remains INTACT
Paneth cells
Located at base of crypts
Secrete antibacterial proteins
Produce stem cells
