CNS中枢神经系统.ppt

Nervoussystem1 DepartmentofAnatomyLuzhouMedicalCollege EditedbyprofessorXiao NervoussystemIntroductionThenervoussystemiscomposedoftwoparts thecentralnervoussystemandperipheralnervoussystem Theformerisrepresentedbythebrainandspinalcord whilethelatterconsistsofthespinalandcranialnerves Theautonomicnervoussystem oftenconsideredasaseparatefunctionalentity isapartcentralandapartperipheral Brain Spinalcord Cranialnerves Spinalnerves Nervoussystemasawhole Thenervoussystempossessesparticularimportanceinallorgansandsystemsofhumanbody Itmodulatesthedifferentcells tissuesandorgans tocompletecertainactivitiesorresponseexteriorstimulusforthebenefitoforganismasawhole Thebrainiscommonlyregardedastheorgansolelyconcernedwiththought memoryandconsciousness Allinformationwehaveconcerningtheworldaboutusisconveyedcentrallytothebrainbyanelaboratesensorysystem NervoussystemIntroduction Receptorofmanykindsactastransducerswhichchangephysicalandchemicalstimuliinourenvironmentintonerveimpulsewhichthebraincanreadandgivemeaningto Attention consciousness emotionalexperienceandsleepareallcentralneuralfunctions Suchhigherfunctionsasmemory imagination 想像力 thoughtandcreativeabilityarepoorlyunderstood 难懂的 butmustberelatedtocomplexneuronalactivity Whilethegrossfeaturesofthehumanbrainarenotespeciallyimpressive 印象 itsversatility 多功能性 potentialcapabilities 濽能 efficiency 效率 andself programmingnature 自我谋略天性 putitinaclassbeyondany electronicbrain NervoussystemIntroduction TheelementsofthenervoussystemThenervoussystemcomposedofnervoustissuethatconsistsofbillionsofnervecells neurons andsupportedbyaspecialvarietyofconnectivetissueknownasneuroglia TheneuronTheneuronareindependentstructuralunitofthenervoussystemandarefunctionalspecializedforreception integration 整合 andtransmissionofcodedinformation 编码 NervoussystemIntroduction RoughgranularEndoplasmicreticulum SmoothgranularEndoplasmicreticulum Microtubule Schwann scell Myelinsheath Lysosomes Lipofuscin脂褐质 Eachneuronpossessesanucleatedcellbodyandtwotypesofprocesses anneuron whichconductsimpulseawayfromthecellbody andoneormoredendritesthatconductsimpulsestowardsthecellbody Bothoftheseprocessesshowmarkedmorphologicaldifference Thecellbodyservesasmetaboliccenteroftheentireunitandconsistsofalarge palenucleusandcytoplasm perikaryon NervoussystemIntroduction Thestructuresoftheneuron Thenuclearenvelopeisdouble layeredmembranewithnumerouspores 小孔 Thechromatin 染色质 consistsmostlyoflargemoleculesofdeoxyribonucleicacid DNA Thenucleolus 核仁 occupiesaprominentpositioninthenucleus whichisrichinribonucleicacid RNA Asinallcells thenucleusengagesinmarkeddegreeofproteinsynthesis Theorganelles 细胞器 containedwithinthecytoplasmarecommontoothercellsinthebody butthereisabundantgranularendoplasmicreticulumthatconstitutestheNisslbody aproteinsynthesisapparatus NervoussystemIntroduction engagein从事于 Thestructuresoftheneuron Themicrotubulesandneurofilamentsinthecytoplasmextendthroughoutthecellbodyandprocessesandconstitutethecytoskeletonoftheneuron whichareinvolvedinthemaintenanceoftheshapeofneuronandfacilitate 易于 transferofsubstancebetweenthecellsbodyandcellprocesses Theneuronalsocontainsabundantlysosomes 溶酶体 andmitochondria 线粒体 forenergymetabolism Therearelipofuscin 脂褐质 granules prominentlyinsomelargeadultneuron whicharebyproductsofmetablism andtheneuromelanin 神经黑色素 granulesinthesubstantianigraandlocusceruleuswhicharethewasteproductofcatecholamine 儿茶酚胺 synthesisprobably NervoussystemIntroduction Thestructuresoftheneuron Theaxonisaslenderprocess Itmayarisefromtheconicalregionofthecellbodycalledaxonhillock orfromthebaseofoneofthemaindendrites Theaxongivesrisetoseveralsidebranchesorcollaterals usuallyorientedperpendicular 垂直的 tothemainaxonprocess Distally theaxonbreaksupintofinebranchesthatendinswollenbuttoncalledbuttonterminaloraxonterminal Thelattercomesintocontactwithotherneuronstoformsynapse orwithmuscletocausemusclecontraction orwiththeglandtocausesecretion Theplasmicmembraneoftheaxonisknownasaxolemma 轴膜 andtheinteriorofaxoncalledaxoplasm 轴索原浆 TheaxoplasmdiffersfromthecytoplasmofthedendritesbycompleteabsenceoftheNisslbody Componentsoftheaxoplasmconsistofagranularendoplasmicreticulum mitochondria microtubulesandneurofilments Theterminalsegmentsofaxoncomprisesnumeroussynapticvesiclesthatcontainneurotransmittersubstances NervoussystemIntroduction Thestructuresoftheneuron BecausetheaxoplasmdoesnotcontainRNA proteinssynthesiscannottakeplaceintheaxon Allaxonalproteins therefore mustcomefromthecellbody andproductsaretransportedbyaperpetual 永久的 axoplasmicmotion someorganelles structuralproteinandneurotransmitterscontainedwithincytoplasmarecarriedbyaxoplasmicflowwhichmovesinbothdirectionsandwithvaryingvelocity Theanterogradetransport movingfromthecellbodytothenerveterminals hastwotypesofrate oneistheslowtransport whichisbulkflow 总体流动 ofaxoplasmcarryingmitochondria lysosomes 溶酶体 andvesicles theotherisarapidtransportwhichmovesthemembrane boundvesicles andothermaterial NervoussystemIntroduction Axoplasmictransport Theretrogradetransports movingfromthesynapticterminaltothecellbody provideafeedbackpassage Somepinocytotic 胞饮的 materialuptakenbyanaxonalterminalsordistaldendritesarecarriedtothecellbodyforutilizationorlysosomaldegradation Theaxoplasmictransportcanbeusedexperimentallytodetermineneuronalconnectivity 连通性 byanaxon tracingtechniqueandgasaclinicimplicationascentripetal 向心力 transportofneurotoxic 神经毒素 andinfectiveagents whichmayberesponsibleforsomedisease NervoussystemIntroduction Axoplasmictransport Thedendritesconstituteprotoplasmic 原浆 extensionsofthecellbody Themainorprimarydendritesarisesfromthecellbodyandthenbranchrepeatedlyinatree likemannertoformacomplexdendritestree Further thedendritesarestudded 颗粒奖的 withalargemembersofthorn 棘 likeprocess dendritespinesorgemmulus 芽 whicharestructuresspecializedforsynopticcontact Inthismannerthedendritesgreatlyincreasethereceptivesurfacearea 接收面积 ofthewholeneuronandthusenhance 增加 thescope 机会 foritsbeinginfluencedbyotherneurons Toalargeextend thediversity 多样性 amongneuronsdependsonthecomplexity configurationsandpositionofthedendrites NervoussystemIntroduction Axoplasmictransport NervoussystemIntroduction Classificationoftheneuron neuron Bipolarneuron pseudounipolarneuron Multipolarneuron AccordingtothenumberOftheirprocesses neuron Sensoryneuron Motorneuron Associationneuron Afferentneuron Efferentneuron Intermediateneuron functionally neuron Small Medium Large From10 200um Bipolarneuron pseudounipolarneuron Multipolarneuron dendrite nucleus axon Nisslbody Axonhillock NervoussystemIntroduction nervousfibers Thelongerprocessesoftheneuronenvelopedbythemyelinsheathandtheneurilemmaaretermednervefibers Themyelinatedfibersaresurroundedbyamyelinsheathandneurilemma Theunmyelinatedfibersarenot however insulated 绝缘的 byamyelinsheath OligodendrocytesformmyelininthecentralnervoussystemwhileSchwanncellsformmyelininperipheralnerves NervoussystemIntroduction Synapses conceptofthesynapse WithinthenervoussystemimpulsesareconductedfromOneparttoanotheralongachainofneurons Theterminalarborizationsoftheaxonofoneneuronramifyinclosecontactwiththecellbodyordentrites lessfrequentlywithaxonicterminalsofmanyothers ConceptOfthesynapses Structuresofthesynapses EachsynapseinvolvesthecloseappositionofapresynapticelementwithapostSynapticelementfromwhichitisseparatedbyasynapticcleft Thepresynapticelementcontainsnumeroussynapticvesiclesinwhichthechemicalsubstanceneurotransmitterispresent Presynapticmembrane Postsynapsemembrane Synapticcleft Synapticvesicle Mitochondria NervoussystemIntroduction Synapses Whenanimpulsearrivesatthepresynapticelement theneurotransmitterDiffusesacrossthesynapticcleftandbindstoreceptormoleculesinthepostsynapticmembrane Asaresult thepostsynapticneuronisactivatedandimpulseisconductedfromoneneurontotheothers The chemicalsynapse involvingthereleasethetransmittersubstanceisthemostcommontypeinthemammaliannervoussystem TheaxonoflowermotorneuronprojectthroughperipheralnervestoMusclecellsandterminateataspecializedportionofthemusclemembraneWhicharecalledneuromuscularjunctionsormotorendplates ThefibersInnervatingthevoluntarymusclesofthebodyandlimbsaretheaxonoflargemultipolarnervecellslocatedinanteriorhornofthegraymatterofThespinalcord IthasbeenestimatedthateachofthesemotorneuronsReceivessynapticconnectionsfromtheterminalaxonalramificationsofUpto1000othernervecells NervoussystemIntroduction TheneurogliaNeurogliacellsoutnumberneuronsinthecentralnervoussystem10 1 Thesecellsappeartoplayanumberofimportantroles includingmyelinformation guidanceofdevelopingneurons maintenaceofextracellularK levels andreuptakeoftransmittersaftersynapticactivity TheastrocytesAstrocyteshavemanyradiatingprocesses someofwhichendatNervecellsandothersatcapillaries TheyareneuroectodermalinOriginandmayassistinthetransferofnutrientsandmetabolicProductsbetweentheneuronsandtheblood NervoussystemIntroduction 2 TheoligodendrocytesOligodendrocytesaresmallerandhavefewerbranchingprocesses theytendtolayinrowsbetweennervefibersandareconcernedwiththeproductionandnourishmentofmyelinsheathsespeciallythosesurroundaxonsinthecentralnervoussystem Theyareneuroectodermalinorigin 3 ThemicrogliaMicrogliaarediminutivecells whichpermeatetheentirecentralnervoussystem TheyaremodifiedmacrophagesandformpartOfthereticulo endothelialsystemandareprobablymesodermalInorigin NervoussystemIntroduction ThereflexandreflexarcReflexesaresubconsciousstimulus esponsemechanism Thereflexarc alinkageofafferentandefferentneurons isdefinedastheentireneuralpathwaythatisinvolvedinareflex Severalstructuresareinvolvedinthereflexarc Theseincludethereceptorwhosestimulationinitiatesanimpulse theafferentneuron whichtransmitstheimpulsethroughaperipheralnervetothecentralnervoussystem wherethenervesynapseswithalowermotorneuronoraninterneuronuptooneormoreinterneuronswhichrelaytheimpulsetotheefferentneurons theefferentneuronwhichpassesoutwardinthenerveanddeliverstheimpulsetotheeffectorandaneffector Theinterruptionofthisreflexarcatanypointabolishestheresponse NervoussystemIntroduction Terminology Graymatter IntheCNS thepartofaggregationsofnervecellbodiesEmbeddedinanetworkofdelicatenerveprocessesisKnownasgraymatter ithasagraycolorduringtheFreshcondition Cortex ThecortexistheoutmostlayerofgraymatterintheCerebralhemispheresorinthecerebellum ThecellBodiesinthecortexarearrangedinmoreorlesswell Definedlaminaeorlayers Nucleus Nervecellswithcommonshape functionandconnectionswithintheCNSaregroupedtogetherintonucleus Ganglion Nervecellswithth