GI tract 2 Flashcards
Crypts of Lieberkunhn
simple tubular glands that extend from the surface epithelium down to the muscular is mucosae
Absorptive cells
secrete disaccharidases and peptidases–bind to microvilli where they produce monosaccharide and amino acids for absorption
lipids are absorbed and reesterified to triglycerides
Goblet cells
Unicellular gland–produces mucin
Few in duodenum and many in ileum
Enteroendocrine cells
Unicellular glands
-synthesize hormones and vasoactive peptides
Closed enteroendocrine cell
no portion exposed to lumen–releases into vasculature
Open enteroendocrine cell
releases into lumen and sometimes vasculature
Paneth cells
Exocrine cell– apical granules contain lysozyme/phospholipase A2/hydrophobic peptides(defensins-antibacterial activity)
Crohn’s Dz–specific disorder of Paneth cells
M(microfold) cells
ONLY found in ileum
- specialized cells covering Peyer’s patches
- BM is discontinuous
GALT
25% of mucosa in the gut
-Peyer’s patches are groups of 20-40 lymphatic nodules found EXCLUSIVELY in the ILEUM
IgA synthesized by plasma cells
Secretory component made by absorptive cells binds IgA dimer – forming secretory IgA—-binds antigens/toxins/microorganisms
Regional difference in Duodenum
Brunner’s glands in the submucosa and squat villi
Regional difference in Jejunum
Most developed plicae circularis
more goblet cells and more slender villi
Regional difference in Ileum
longest villi
has the most goblet cells
has Peyer’s patches
Colon and Cecum have temporary folds of mucosa and submucosa. what are they called
Plicae semilunares
semicicular folds
Does the colon and cecum have villus?
NO
-only crypts of Lieberkuhn
