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33 Cards in this Set
- Front
- Back
3 major tissue layers in GI tract
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mucosa
submucosa muscularis externa |
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componants of mucosa
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Epithelial (squamous in esophagus, columnar in SI)
Lamina Propria Muscularus Mucosa |
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purpose & composition of lamina propria
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maintain epi layer (like basement membrane)
collagen & elastin |
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purpose of muscularis mucosa
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maintain structure lamina propria (folds & ridges)
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components of submucosa
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collagen & elastin
nerves, vessels & glands |
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purpose & components of muscularis externa
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peristalsis
inner is circular outer is longitudinal |
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smooth muscle communicates via ...
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gap junctions:
connexins form connexons 2 connexons line up & form ion channel |
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composition of serosa
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simple squamous epithelium
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6 sphincters in GI tract
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UES, LES, Pyloric, Ileocecal, EAS, IAS
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esophageal peristalsis
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primary & secondary
circular then longitudinal ctx 8-10 s (or 5-8 upright) |
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LES relaxes ...
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at initiation of swallow
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Phase shift
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amplitude of wave "travels" along length of tube
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patient presents with:
dysphagia, belching, regurgitation of undigested food, minimal reflux |
Achalasia
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barium eval with "beak like projection" & distended esophagus
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achalasia
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Achalasia results from
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degeneration of ganglion in muscular layers
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treatment for achalasia
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pneumatic dilation (3% risk of rupture, 75% get relief)
surgery botox (60% with relief at 1 year) |
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Mechanism of botox
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Synaptotagmin (R) recognizes heavy chain
Internalized Light chain is metalloproteinase (toxin) LC cleaves SNAP 25 and ___________ Can't fuse with membrane protein to allow ACh into terminal |
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diffuse esophageal spasm
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uncoordinated peristalsis but LES with ability to relax
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2 actions of stomach
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mix food with secretions
push into intestines |
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muscle involved in mechanical digestion in GIT
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oblique muscle layer (innermost) of stomach
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normal epithelials of esophagus transformed into columnar
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Barett's esophagus
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progression of Barett's
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normal
Barett's changes with low grade dysplasia with high grade dysplasia |
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control of gastric emptying
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at pyloric sphincter
size dependent (dog experiment with liver & spheres) |
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pressures in stomach
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amplitude increases from fundus to pyloric sphincter
phase shift |
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electrical activity in stomach
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little depolarization at top, increases as go down
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Slow wave potential
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5/minute stomach
12/minute in SI maintains potential near threshold |
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characteristics of small intestine motility
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slow wave potential segmentation
peristalsis |
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segmentation
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"mixing" in SI, circular smooth muscle
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characteristics of large intestine motility
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Haustral contractions
Mass movements |
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triangular units, slow to develop to relax, mix & remove fluid
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Haustral contractions (LI)
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1-3 x per day
propulsion in LI series contractions lasting 10-30 min |
Mass movements (Haustral ctx cease)
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passage from SI to LI
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at ileocecal sphincter
ileal distention, sphincter relaxes, colonic pressure causes feedback to tighten sphincter |
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effect of mass movement at rectum
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rectum contracts
IAS relaxes EAS gets spike in electrical activity conscious decision to relax or contract EAS |