Lecture 16: Digestive System I

  1. Adventitia and not serosa
    esophogus & rectum
  2. Muscularis externa (propria)
    • Inner Circular- contracts tube
    • Outer Longitudinal (shortens tube)
    • Auerbach's plexus
    • Mix contents, move contents down tract, reg volume
    • form the pyloric-duodenal sphincter
  3. Submucosa
    • DCT
    • Meissner's plexus
    • support submucos glands
  4. Mucosa
    • 3 components:
    • epithelium, lamina propria, muscularis
    • mucosae
  5. Gland postions
    • Stomach- glands in lamina propria (abouve MM)
    • SI & esoph- glands in submucosa (below MM)
  6. Muscularis mucosae
    • Also has inner circular & outer longitudinal
    • tone, keep lumen open
    • SI- mov't of villi
    • *esophagus- ONLY outer longitudinal
  7. Esophagus
    • *adventitia-- except short potion withing abdominal cavity, only outer longitudinal MM
    • Tough, stratified squamous epithelium
    • Lubricating glands: submucosal esophagela glands & cardiac galnds (near stomach) in lamina propria
  8. Lamina proria
    • CT
    • Contains: vascular system, macrophages, lymphocytes, plasma cells, mast cells, eosinophils, fibroblasts,
    • smooth muscle cells
  9. Stomach glands
    • fundic- gastric gland called fundic gland
    • cardica& pyloric- mucous glands
  10. 5 cells of gastric glands (i.e. fundic gland)
    • 1. surface mucous cells
    • 2. mucous neck cells
    • 3. parietal cells
    • 4. chief cells
    • 5. enteroendocrine cells
  11. surface mucous cells
    • Mucous granules apical side
    • Lines surface and pits
    • Carbs with PAS
  12. mucous neck cells
    • Beneath pit, near neck
    • Random granules
    • Dark ganueles on EM
    • Antimicrobial (H. pylori) activity
  13. parietal cells
    • neck, more deeper
    • Secret intrinsic factor
    • Apical- secrete HCl
    • Basal- secrete bcarb to neutralizer acid that might have leaked into lamina propria
    • Many dark mitochondria
    • tubulo/vesicular sturctures duse with internal canaliculus (PAS invaginations)
    • Green core "fried egg" on PAS
  14. Intrinsic factor
    • secreted by parietal cells
    • required for B12 absorption
    • absence: pernicous anemia- RBS need B12
  15. chief cells
    • bottom of tubular glands
    • granules: varying shades but lighter than cytoplasm
    • Lots of ER, Golgi, secretory vesicles
    • zymogenic cells- secreter pepsinogen
  16. enteroendocrine cells (enterochromaffin, argentaffin)
    • Single celled gland
    • Basal granules
    • Part of epithelium, secrete into lamina propris->blood stream
    • Many secretions: ie. gastrin- reg parietal cell functn, division of mucous neck cells
    • In crypts and villi, secrete CCK
  17. Small intestine-
    plicae circulares, crypts of Lieberkuhn, Brunner's glands,
    • plicae circulares (Kerckring)- permanent infoldings with a core of submucosa that increases surface area
    • crypts of Lieberkuhn - tubular glands that begin at bottom of intervillous space
    • Submucosal Brunner's glands in duodenum; empty into bottom of crypts
  18. SI->5 types of epithelium
    • 1.absorptive cells (enerocytes)
    • 2.goblet cells
    • 3.paneth cells
    • 4. enteroendocrine cells
    • 5. progenitor cells
  19. absorptive cells (enterocytes)
    chylomicron packaged here, released into intercellular spane->central lacteals to larger lymphatic->blood stream->liver
  20. paneth cells
    • base of crypts
    • Antimicrobial- reg bacterial flora
    • refractile, intesely eosinophilic
    • antibacterial NZs
    • alpha-defensin: disrupts bacterial growth
    • granule secretion regulated by: a. bacteria b. CCK, enteroendocrine cell product
  21. Variations in SI
    • Jejunum- no submucosal glands (Brunner's)
    • Ileum- no submucosal glands, Peyer's patch- lymphoid tissue
  22. LI
    • Appendix
    • Colon: Villi disappear; more goblet cells- mucus for lubrication; no lymphatics
Card Set
Lecture 16: Digestive System I
digestive tract canal, glands