2. Setting the Scene (Anatomy) Flashcards
(63 cards)
What are the two main types of the epithelial cell found in the GI tract and where r they found?
Stratified squamous in oesophagus and distal anus
o Everything in between is simple columnar
Function of stratified squamous non keratinised epithelium found in GI tract? Hint: think about where it’s found specifically
Resists abrasion/stress (physical + chemical). Hard food and faeces bcs found at mouth and distal anus.
Non keratinised means it SECRETES MUCUS to protect + lubricate.
Describe the enterocytes and their function
A simple columnar epithelial cell that absorbs
o Predominant cell of small intestine and colon
o One cell thick!
o Need to transport nutrients through
- Apical membrane
- Basolateral membrane
o Blood vessels/lymphatics lie immediately below the
enterocyte (in LP)
What is a specialised feature of enterocytes?
◦ Microvilli (collectively termed brush border)
Where are goblet cells found and how do they get their name?
o Scattered in between enterocytes
o Increasing in number from duodenum to colon
o They get their name from a narrow base and larger
apical size
Why is the nucleus of a goblet cell at its base?
Mucus pushes it down to the base
What does the mucus from goblet cells protect the epithelia from?
o Friction (acts as lubricant)
o Chemical damage (acidic environment)
o Bacterial inflammation (forms physical barrier)
WHat are mucous producing cells in the stomach called and what else do they produce?
Gastric surface mucous cells (foveolar cells)
o Line gastric mucosa/gastric pits
o Secrete mucus/HCO3 that forms barrier to stomach acid
Describe foveolar cells
o simple columnar epithelium
o divided in two groups:
- surface mucous cells, which line the surface and the gastric pits
- mucous neck cells, which are a part of the neck of gastric glands
What are the permanent folds in the intestine called?
Plicae circulares or vulvulae conniventes
What two factors of the small intestines increase surface area?
permanent fold
villi
microvilli
What are the folds in the stomach called and what do they allow?
Rugae, allows the stomach to be easily expandible
What are haustra?
Sacculations in the large bowel
Where are crypts found?
In small and large intestine
o Sometimes known as crypts of Lieberkuhn/intestinal glands
What specialised cells are found within the crypts and what are their functions?
o Stem cells
o Paneth cells
o Enteroendocrine cells
How does the gut maintain its epithelial barrier to protect from stomach acid?
Contains stem cells that replace epithelia every 2-4 days
What is the role of a Paneth cell?
Secretes antibacterial proteins, which protect stem cells of gut
Found at the base
What are Brunner’s glands and where are they found?
Proximal duodenum - secrete alkaline mucoid material into crypts to neutralise acidic chyme from stomach.
Function of columnar cells found in the colon (large intestine)? Why do they contain lots of ATPase pumps?
Extract final amounts of water from faecal material. Does this against a strong conc grad so requires a lot of energy. Active fluid transport.
WHat are the 4 layers of the gut tube?
Mucosa (innermost)
o Submucosa
o External muscle layers
o Serosa (outermost)
What are the layers of the mucosa?
epithelium, lamina propria, muscularis mucosa
What is the function of the epithelial layer of mucosa?
o Selectively permeable barrier o Facilitate transport and digestion of food o Promote absorption o Produce hormones o Produce mucus
What is contained within the lamina propria and what does it produce?
o Lots of lymphoid nodules and macrophages
o Produce antibodies (mainly IgA which is resistant to
proteases)
Protect against bacterial/viral invasion
What is the muscularis mucosae?
o Layers of smooth muscle orientated in different
directions
o Keeps epithelium in contact with gut contents
