复旦生理学课件-digestion & absorption

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1、Chapter6DIGESTION&ABSORPTION§1.IntroductionConceptofdigestion&absorption*Mechanical&chemicaldigestionCharacteristicsofdigestivesmoothmuscles*Generalcharacteristics*ElectrophysiologicalcharacteristicsRestingpotential(RP)Slowwaveorbasicelectricalrhythm(BER)Actionpotential(AP)Electrica

2、lactivities&contractionofdigestivesmoothmusclesSecretionofdigestiveglands*MainfunctionsofdigestivefluidsGastrointestinalinnervation*Intrinsic(orenteric)nervoussystemSubmucosal&myentericplexus*ExtrinsicnervoussystemParasympathetic&sympatheticnervesGastrointestinalhormones*Generalfun

3、ctions*Brain-gutpeptidesIntrinsic(orenteric)nervoussystemExtrinsicnervoussystem§2.Digestioninthemouth&esophagusSaliva&itsfunction*Nature&CompositionofsalivapH6.6~7.1,99%waterSalivaryamylase,lysozyme,salt,etc.*FunctionsofsalivaMoistenthecavity&solvefood;keepthemouthclean;anti-bacteria

4、;digeststarch*RegulationofsalivarysecretionPureneuroregulationConditioned&unconditionedreflexMasticationorchewing&itseffects*Definition*EffectsBreakuplargefoodparticles;mixesthefoodwithsaliva;aidswallowingDeglutitionorswallowing*Definition*Process1st,2nd&3rdphasePeristalsis&lowereso

5、phagealsphincterPeristalsisoftheesophagus§3.DigestioninthestomachGastricjuice&itssecretion*Nature,Compositions&functionspH0.9~1.5,colorless,1.5~2.5L/dayHydrochloricacid(HCl)SecretedbyparietalcellsBasicsecretion:0~5mmol/hMaxsecretion:20~25mmol/hMechanismofHClsecretionFunctions:seenext

6、pageRelationshipbetweenmaxvolumeofHClsecretion&thenumberofparietalcellsFunctionsofHCl:Turnpepsinogenintopepsin&provideamediumoflowpHfavoringpepsinaction;Killmanyswallowedvirulentorganisms;Promotethesecretionofpacreas&bile;Promotetheabsorptionofcalcium&ferrumPepsinogenSecretedbychiefce

7、lls&activatebyHClFunction:digestproteinsintoproteoses,peptones,polypeptides,withlittlefreeaminoacidsMucusSecretedbyneck&surfacemucouscells,cardiac&pyloricglandsFunction:formmucus-bicarbonatebarrierIntrinsicfactorSecretedbyparietalcellsFunction:PromotetheabsorptionofVitB12*Regulationof

8、gastr