Feb14 M1-Histo lecture 2 Flashcards
dx tool to distinguish the duodenum
Brunner’s glands (mucous glands) in the submucosa
dx tool to distinguish the jejunum
submucosa of dense CT (but no glands) pushes mucosa to make permanent plicae circularis (or valves of Kerkring)
ileum appearance on histo
plicae circularis get shorter and disappear
charact of SI mucosa
villi with small crypts at their base called crypts of Lieberkuhn (openings looking like circles on histo)
where’s the LP in SI mucosa + its characteristics
is loose CT (very cellular) fills the space under villi and between the crypts
Brunner’s gland fct in the duodenum
open near the crypts and make mucin that is rich in bicarb to neutralize acidic chyme from stomach
charact of serosa in the jejunum
infiltrated by fat tissue
rugae of the stomach vs plicae circularis of the jejunum
rugae disappear when stomach dilated
plicae circularis never disappear but simply pushed against the wall of the intestine
main concept in distinguishing the 3 parts of the SI
submucosa (Brunner’s or plicae or dimishing plicae)
SURFACE epithelium composition in the small intestine
simple columnar epithelium: absorptive enterocytes with striated border + mucus-secreting goblet cells
where are the stem cells in the small intestine (stomach = isthmus) + what they can do
in the crypts. can divide to make committed cells and then these committed cells (ex enterocytes) can divide outside of the crypts to make more cells like them
goblet cells charact
big, bulky, pale, mucous secreting
absorptive enterocytes charact
simple columnar epithelium, more abundant, brush border, nucleus at the basal side. cover the intestinal crypts
important charact of intestinal mucosa
form villi with lymphatics and blood capillaries inside them (in LP in middle of the villus)
turnover rate of intestinal mucosa epith and meaning
45 days. time needed for cells to migrate from base of crypt to top of villus and get sloughed off
clinical importance of turnover rate of intestinal epithelium
ANY cancer treatment of ANY cancer affects stem cells of gastric and intestinal mucosa and will get bleeding eventually
what allows motion of the villi in the SI
muscularis mucosa (SM)
name of lymphatics in villi and what are they made of
lacteals (lymphatic ‘‘capillaries’’): endothelial layer of squamous simple epithelium
intestinal stem cells on histology
pale cells at the base of the crypts, between the paneth cells
paneth cells charact and what creates them
(made by stem cells). zymogenic and have granules. make lysozymes to destroy bacterial walls + regulate intestinal flora
other cell type in middle of SI crypts + fct
enteroendocrine cells. face BM, like in stomach, and screte contents in LP
phenomenon observed in SI crypts
lot of mitosis (for future goblet cells or enterocytes)
how cell migration to lumen occurs in SI mucosa and what cells
all except Paneth cells. mature as they go to the lumen and push each other
3 cell types in villi (simple columnar epithelium)
- columnar cells with brush border (absorptive enterocytes)
- goblet cells
- M cells (microfold cells)
