Flashcards in Histology of the GI Tract (In class)- Cole Deck (28)
what is the purpose of villi?
to increase surface area and therefore absorption
What are the 4 degrees of folding?
1. plicae circulares (PC)
2. Intestinal villi
3. Intestinal glands (Crypts of Liberkuhn)
4. microvilli on surface of enterocytes
where are pilcae circulares present?
duodenum and disappear mid-ileum
what does the length of villi depend on?
degree of distention of intestinal wall and smooth muscle contraction
Instestinal glands are what kind of glands? what do they have a lot of?
simple, tubular glands with lots of goblet cells
What other cells are part of glands?
paneth and enteroendocrine cells
Microvilli have what on them?
What is segmentation and what does it serve to do? what controls it?
a pattern of annular contraction forms compartments, mixes chyme; ANS
Peristalsis is what?
coordinated contraction with relaxation of next section; pushes food thru
what is the beginning of the lymphatic system in the villi?
what do lacteals collect from digested products?
intrinsic input for innervation comes from?
mucosa and muscle wall of small intestine
extrinsic input for innervation comes from?
CNS thru vagus and sympathetic n. trunks
what distinguishing feature does the duodenum have histologically?
leaf-like villi, Brunner's glands (mucous glands), few goblet cells
Jejunum has what histologically?
lots of plicae circulares, irregular villi with finger-like shape, more goblet cells, no brunner's or peyer's patches
ileum has what histologically?
peyer's patches (collection of lymphoid tissue), SHORTER finger-like villi, most goblet cells, M cells (antigen presenters)
what are enterocytes? what do they have on top? these contain?
absorptive cells; microvilli- intermembranous enzymes to break carbs down to hexoses
what does gastrin do?
stimulates gastric motility, HCl (parietal cells) and insulin
what Ig is secreted by GALT?
what is the purpose of a fecal microbiota transplant?
replace good bacteria that has been killed or suppressed; prevents bad bacteria to overpopulate
major function of large intestine?
absorbs ions and water
what's a distinguishing feature of large intestine?
what does active transport of sodium do?
concentrates chyme into feces
what are the enterocytes of the large intestines job? what is it regulated by?
sodium and chloride absorption; mineral corticoids
what does aldosterone do to enterocytes?
increases number of Na channels
what does the appendix have to distinguish it?
lots of lymphoid tissue in walls
histologically what happens at the ano-rectal junction?
simple columnar to stratified squamous epithelium