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1、CellularNeurobiologyCellularNeurobiologyNeuroscienceResearchInstitutePekingUniversityDepartmentofNeurobiologyPekingUniversityHealthScienceCenterAlbertCheung-HoiYU于常海于常海北京大學神經科學研究所北京大學神經科學研究所OneoftheCajalsOneoftheCajalsmanydrawingsofmanydrawingsofBraincircuityBraincircuityTheletterslabelthedifferente
2、lementsCajalidentifiedinanareaofthehumancerebralcortexthatcontrolsvoluntarymovement.Neurons:Excitablecells“wiring”“SignalSenders”Neuroglia:Support,Nurturing,InsulationCellularComponentsCellularComponentsNerveCellsNerveCellsNeuronsNeurogliaCellbody(soma;perikaryon)Axon:onlyone(branchesarecollaterals;
3、terminalsareendfeet)Dendrites:muchshorter;oneormorethanone;branchextensivelyintodendritictreesStructureofNeuronsStructureofNeuronsAxonHillock(Axonalendfeet)TheAxonTheAxonandAxonandAxonCollateralsCollateralsCellBody(Soma):LifeSupportProteinSynthesisSingleNucleus,RER(NisslBodies)Axon:Longestprocesstra
4、nsmitsmessagesawayfromcellbodyDendrites:MultipleprocessesoffcellbodyreceivemessagesNeuronsNeuronsStructure&FunctionStructure&FunctionNeuronsaresimilartoothercellsinthebodyinsomewayssuchas:1.Neuronsaresurroundedbyamembrane.2.Neuronshaveanucleusthatcontainsgenes.3.Neuronscontain:Whatareinsideofaneuron
5、?Whatareinsideofaneuron?NucleusNucleolusMicrofilaments/NeurotubulesEndoplasmicReticulum(ER)MitochondriaGolgiApparatusNisslBodiesOthersDendrites:dendritetreeAxon:axonhillock(axonorigination)axonaltransportsysteminitialsegment(firstmyelinsheath)actionpotentialgenerationmyelinsheathAxonandDendritesAxon
6、andDendritesAxonsDendritesTakeinformationawayfromthecellbodyTakeinformationtothecellbodySmoothsurfaceRoughsurface(dendriticspines)Generallyonly1axonpercellUsuallymanydendritespercellNoribosomeHaveribosomesCanhavemyelinNomyelininsulationBranchfurtherfromthecellbodyBranchnearthecellbodyDifferencesbetw
7、eenAxonsandDendritesNeuronClassificationbyShapeNeuronClassificationbyShapeMultipolar:“multi-”manyprocessesMajority:Singleaxon,manydendrites(motorneuronandinterneuron)Bipolar:“bi-”2processesFoundinsomesensoryorgans(retina,taste,smell,innerearneuron)Unipolar(pseudo-unipolar):“uni-”1process(withbranche
8、s)Sensoryafferentneurons(dorsalrootganglia)ClassificationofClassificationofNeuronsbyNeuronsbyMorphologyMorphologyClassificationofNeuronsClassificationofNeuronsbyAxonLengthbyAxonLength1.GolgitypeINeuronsLongaxons(longestfromthecortextothetipofspinalcord,50-70cm)2.GolgitypeIINeuronsShortaxons(shortest
9、axonsterminateonlyafewmicronfromcellbody,interneurons)3.AmacrineNeuronsAnunusualcelltype,lackaxonsSensoryneuronfromreceptortoCNS;receivestimuliandtransmitafferentimpulsestoCNSInterneuronscommunicatingbetweenneurons;formcircuitsintheCNSMotorneuronfromCNStoeffectorcells;deliverefferentimpulsesoutthrou
10、ghthePNStotheeffectorstocarryouttheactionsdirectedbytheCNSFunctionalClassificationofNeuronFunctionalClassificationofNeuronEXCITABLEMembrane:Abletoregulatethemovementofions(charges)acrossandalongmembraneSIGNAL TRANSDUCTIONDONOTReplicate:Damagedcellscannotbereplaced!ImportantFeaturesImportantFeatures
11、ofof NeuronsNeuronsActionActionPotentialPotentialFourFunctionalRegionsofModelNeuronsFourFunctionalRegionsofModelNeuronsImpulsetransmission:electricalchemicalMorphology:axodendriticaxonsomaticaxoaxonicdendrodendriticClassificationofSynapsesClassificationofSynapsessynapse4VesiclesreleaseNeurotransmitt
12、ersChemicalsynapse:presynapticknob(presynapticcomponent)synapticvesiclessynapticcleftpostsynapticmembrane(postsynapticcomponent)Electricalsynapse:gapjunctionsSynapseStructuresSynapseStructures TypesofsynapseDis-tanceCytoplasmiccontinuityUltrastruct-uralcomponentAgentoftrans-missionSynapticdelayDirec
13、tionoftrans-missionElectrical3.5nmYesGap-junctionchannelIoncurrentVirtuallyabsentUsuallybidirectionalChemical20-40nmNoPresynapticvesicleandactivezone;postsynapticreceptorsChemicaltransmittersSignificant:atleast0.3ms;usually1-5msorlongerUni-directionalDistinguishingPropertiesofDistinguishingPropertie
14、sofElectricalandChemicalSynapsesElectricalandChemicalSynapsesAtachemicalsynapse,neuronstransmitinformationacrossacleft.1.SmallMoleculeNeurotransmitterSubstancesAcetylcholine (ACh); Dopamine (DA); Norepinephrine (NE); Serotonin (5-HT); Histamine2.AminoAcidsGamma-aminobutyric acid (GABA); Glycine; Glu
15、tamate; Aspartate3.NeuroactivePeptides-partiallist!Bradykinin; beta-endorphin; calcitonin; cholecystokinin; enkephalin; dynorphin; insulin; gastrin; substance P; glucagon; secretin; vasopressin; oxytocin, etc.ListofSomeNeurotransmittersListofSomeNeurotransmittersAxonaltransport:intracellularcommunic
16、ationBidirectionalmechanism:anterogradetransportretrogradetransportClassifiedbytransportrates:slowtransportsystem(0.2to1mm/day)fasttransportsystem(200to400mm/day)AxonalTransportSystemsAxonalTransportSystemsHitchingaRideon“Retrorail”Membranesoforganellesinvolvedinsynaptictransmissionarereturnedtothec
17、ellbodyforreuseordegradationNucleusCytoskeleton(Anterogradetransport)ComponentRate(mm/day)StructureandcompositionFasttransportAnterograde 200-400Smallvesiculotubularstructures,neurotransmitters;membraneproteinsandlipidsMitochondria50-100MitochondriaRetrograde 200-300LysosomalvesiclesandenzymesSlowtr
18、ansportSCb2-8Microfilaments,metabolicenzymes,clathrincomplexSCa0.2-1NeurofilamentsandmicrotubulesMajorRateComponentsofAxonalTransportMajorRateComponentsofAxonalTransport1.Neuronshavespecializedprojectionscalleddendritesandaxons.Dendritestakeinformationtothecellbodyandaxonstakeinformationawayfromthecellbody2.Neuronscommunicatewitheachotherthroughanelectrochemicalprocess3.Neuronscontainsomespecializedstructures(likesynapses)andchemicals(likeneurotransmitters)4.NisslBodies5.DONOTReplicate:Damagedcellscannotbereplaced!NeuronsdifferfromOtherCellsNeuronsdifferfromOtherCells
