W3 - Lower GI Tract Flashcards
Why is there not much muscle in the SI compared to the stomach and why do the plicae folds of the SI not have any HM stretching signals like the stomach?
Not much muscle - food already broken down so less need, No HM stretching signals - SI primary function is absorption not secretion
What are Peyer’s patches and where are most/least found?
Aggregations of lymphoid follicles that bulge into the lumen, least in duodenum, most in ileum
Epithelium overlies the domes formed by Peyer’s patches, what are these specialised for?
Antigen uptake
What cells in the small intestine have microvilli (increase SA), which produce mucin and which are present at the base of crypts?
Enterocytes, goblets cells, paneth AND stem cells
What is the primary function of the duodenum?
Neutralises stomach acid
What is a crypt the equivalent of in the intestine?
A gland
What 3 things are absorbed along the microvilli on the apical surface of the enterocytes?
Ions, sugars and amino acids
Under the epithelial cells on the are the lamina propria cells, what cell type are these primarily?
Immune cells
The glycocalyx contains enzymes secreted by absorptive cells for final stages of sugar and protein digestion, what else do they do in terms of microvilli?
Increase SA by bedding microvilli and protect the microvilli
Acid mucopolysaccharides and what make up the glycocalyx?
Glycoproteins
The SC are found near the bottom of the crypt in the SI, what cells help them by keeping the crypt sterile?
Paneth cells
What is the region called where the SCs are consistently undergoing mitosis in the crypt of the SI?
Transit-amplifying cells
How long does it take to overturn the the entire amount of epithelial cells in the bowel?
4-7 days
How many times does a crypt divide within a person’s entire lifetime?
3
All cells in SI crypts (goblet, paneth, enterocyte, neuroendo) are derived from a single SC, what do you call these lineages?
Clonal