crypt villus dynamics and small intestinal cell response SDL Flashcards
what are the arrows pointing to
crypts
where is the muscularis mucosae and what does it do
In the small intestine, the muscularis mucosae is located within the mucosa, specifically situated deep to the lamina propria (connective tissue) and superficial to the submucosa. It forms a thin layer of smooth muscle fibers that run parallel to the surface epithelium.
- regulates mucosal fold shape
- controls local movements of the mucosa (aids in mixing of lumen contents)
- supports and protects mucosa by maintaining structural integrity
- facilitates nutrient absorption through movements
in which parts of the GIT are villi found and what are their function
- extend into lumen of small intestine, most prominently in the jejunum and ileum
- function to increase surface area, absorb nutrients, secrete digestive enzymes, mix, absorb lymphatics
how do cells move along the villi
where are cells lost from on the villi
- stem cell division begins in crypts
- as they divide the give rise to progenitor cells that migrate upwards or downwards where they can then differentiate into matture cells
discuss how the process of the epithelial cell escalator of the villi maintain villus health and how damage to the villus can be repaired
- continuous renewal and tunrover of cells
- repair = activation of stem cells and migration and differentiation of cells
where do you find goblet cells
- scattered among epithelial cells of vili but more abundant in ileum than duodenum
- also in large intestine
what intracellular features of goblet cells allow them to secrete mucin
- mucin granules
- glycosylation
- release through exocytosis
do goblet cells have any absorptive capacity
no
- dont have any absorptive structures (microvilli)
what features do goblet cells lack which are most associated with absorption processes for amino acids and carbohydrates
- microvilli
- transport proteins
- enzymes for digestion
- mitochondrail density
- specialised tight junctions and barier function
what stem cells fo goblet cels arise from and where are they located
stem cells from crypts of lieberkuhn
how do goblet cells respond to inflammation
- increse mucin production
- alter mucin composition (glycosylation pattern changes viscosity patterns etc)
what kind of feedback mechanism tells the crypt to work quickly to re form a damaged villi
- stem cell activation
- signalling pathways and growth factors
- immune response and inflamamtory signals
- feedbakc from microbiota
