-
Adventitia and not serosa
esophogus & rectum
-
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
-
Submucosa
- DCT
- Meissner's plexus
- support submucos glands
-
Mucosa
- 3 components:
- epithelium, lamina propria, muscularis
- mucosae
-
Gland postions
- Stomach- glands in lamina propria (abouve MM)
- SI & esoph- glands in submucosa (below MM)
-
Muscularis mucosae
- Also has inner circular & outer longitudinal
- tone, keep lumen open
- SI- mov't of villi
- *esophagus- ONLY outer longitudinal
-
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
-
Lamina proria
- CT
- Contains: vascular system, macrophages, lymphocytes, plasma cells, mast cells, eosinophils, fibroblasts,
- smooth muscle cells
-
Stomach glands
- fundic- gastric gland called fundic gland
- cardica& pyloric- mucous glands
-
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
-
surface mucous cells
- Mucous granules apical side
- Lines surface and pits
- Carbs with PAS
-
mucous neck cells
- Beneath pit, near neck
- Random granules
- Dark ganueles on EM
- Antimicrobial (H. pylori) activity
-
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
-
Intrinsic factor
- secreted by parietal cells
- required for B12 absorption
- absence: pernicous anemia- RBS need B12
-
chief cells
- bottom of tubular glands
- granules: varying shades but lighter than cytoplasm
- Lots of ER, Golgi, secretory vesicles
- zymogenic cells- secreter pepsinogen
-
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
-
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
-
SI->5 types of epithelium
- 1.absorptive cells (enerocytes)
- 2.goblet cells
- 3.paneth cells
- 4. enteroendocrine cells
- 5. progenitor cells
-
absorptive cells (enterocytes)
chylomicron packaged here, released into intercellular spane->central lacteals to larger lymphatic->blood stream->liver
-
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
-
Variations in SI
- Jejunum- no submucosal glands (Brunner's)
- Ileum- no submucosal glands, Peyer's patch- lymphoid tissue
-
LI
- Appendix
- Colon: Villi disappear; more goblet cells- mucus for lubrication; no lymphatics
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