GI physiology lecture 4

  1. gastric motility
    • filling: involves receptive relaxation, triggered by eating, mediated by vagus nerves
    • storage: in body of stomach
    • mixing: in antrum of stomach
    • emptying: regulated by cells in duodenum
  2. pce makers of the gut
    • interstitial cells of cajal
    • conducts slow wave to smooth muscle
    • L type Ca action potential (allows in Ca)
  3. force of muscle contratcion
    • directly related to amplitude and frequency of APs
    • AP occurs once slow wave reaches AP thresh hold
  4. Antral contraction
    • propulsion: bolus pushed toward pyloris
    • Grinding: the antrum churns trapped material
    • Retro pulsion: bolus pushed back into proximal stomach
  5. Gastric emptying:
    • stomache
    • amount of chyme regulates strength of contraction
    • duodenum
    • fat: sdf
    • Acid: inhibbits emptying until neutralized
    • Hypertonicity: inhibitted when osmolarity starts to rise
    • distention: too much chyme in the duodenum inhibits emptying of more chyme
    • factors outside the GI system
    • emotion: alters autonomic system which can inhibit or stimulate emptying
    • Pain: increases symp activity which inhibits motility and emptying
  6. vomiting/emisis
    • coordinated by vommiting center in medulla from brain stem
    • diaphragm pushes down on stomache
    • abdominal viscera contractsvorcing viscera up
    • therefor stomache squeezed
  7. vomitin/emisis
    • les and ues contract
    • glotiss closes and uvula is raised to close off nose
    • initiated ba tactile stimulation at back of throat and irriatation of stomach
    • chemicals (emitics)trigger zone next to vomiting center
    • psychogenic factors can effect too
  8. pancrease
    • both exoctrine and endocrine tissue
    • located behind and below stomach
    • endocrine: islets of langerhans secret insulin and glucagon
    • exocrine: secretes pancreatic juice with enxymes from acinar cellsand aqueous alkaline from duct cells
  9. pancreatice enzymes:
  10. pancreatic secretions
    trypsunogen: activated by enteropeptidase into trypsin which converts zymogens into enzymes
  11. zymogens and enzymes
    • zymogens:
    • chymostrypsinogen
    • procarboxypeptidase
    • procolipase
    • prophospholipase

    • enzymes:
    • chymotrypsin
    • carboxypeptidase
    • colipase
    • phospholipase
  12. comthin
  13. trypsin out put
    occurs only during feeding times and is greatly reduced at night during fasting
  14. bla
    • secretin: creates cAMP
    • CCK (colocystic kinin): mobilizes intracellular calcium
    • both trigger phosphorylation of structural and regulatoryproteins
    • enzymes are then washed into duodenum by ductalar secretion
  15. secretin
    stimulates CFTR by cAMP
  16. negative feed back by secretin
    • increased secretin release
    • increase in ductalar bicarbinate secretion
    • lowerse ph in duodenum
    • s cells release more
  17. sadklhj
  18. hormonal control of pancreatic secretion
    type up system looop
  19. what is the evidence that amino acids stimulate CCK secretion from I cells in the duodemun?
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GI physiology lecture 4