Lecture 2- Epithelia of the gut Flashcards
types of epithelium in the gut
stratified squamous
simple columnar
where is stratified squamous found
the oesophagus and distal anus
where is simple columnar found
everything between the oesophagus and the simple columnar
the enterocyte
- simple columnar epithelial cell that absorbes
- predominant cell of s.intest and colon
- one cell thick
enterocyte needs to transport nutrients through
the apical membrane and basolateral membrane
where do blood vessels/ lymphatics lie
immediately below the enterocyte
features of the enterocyte
microvilli (brush border)
goblet cells are dound
scattered between enterocytes
where are there increasing numbers of goblet cells
from duodenum to colon
where is nucleus found in goblet cell
mucus comprresses nucleus to its base
shape of goblet cell
narrow base and larger apical size
what do goblet cells secrete
mucus
mucus protects the epithelia from
friction, chemical damage and bacterial inflammation
gastric surface mucous cells (foveolar cells) line
gastric mucosa/ pits
foveolar cells secreate
mucus/ hCO3 that forms barrier to stomach acid
why is the GI tract not flat internal surface
absorptive area needs as large a surface area as poss
what makes the GI tract not flat to help with absoprtion
permanent folds/ villi/ microvilli
villi
increase absorption in absorptive areas
- small intestine not colon)
crypts found in the
small and large intestine
what specialised cells do crypts have
stem cells
paneth cells
enteroendocrine cells
stem cells
constantly divide to replace epithelia (every 2-4 days)
paneth cells located
paneth cell (located at base of crypts)
role of paneth cells
secrete antibacterial proteins protecting stem cells
enteroendocrine cells are predominantly located
deeper in crypts and gastric glands
glandular tissues in the gut (exocrine) are made up of organised secretory cells called
acini and tubules and are connected to a duct
example of exocrine glands in the GI tract
salivary glands
pancreas
brunners glands
