中枢神经系统解剖英文版.ppt

Nervoussystem1,DepartmentofAnatomyLuzhouMedicalCollege,EditedbyprofessorXiao,NervoussystemIntroductionThenervoussystemiscomposedoftwoparts,thecentralnervoussystemandperipheralnervoussystem.Theformerisrepresentedbythebrainandspinalcord;whilethelatterconsistsofthespinalandcranialnerves.Theautonomicnervoussystem,oftenconsideredasaseparatefunctionalentity,isapartcentralandapartperipheral.,Brain,Spinalcord,Cranialnerves,Spinalnerves,Nervoussystemasawhole,Thenervoussystempossesses(拥有)particularimportanceinallorgansandsystemsofhumanbody.Itmodulates（调整）thedifferentcells,tissuesandorgans,tocompletecertainactivitiesorresponse（反射）exteriorstimulus（外界刺激）forthebenefitoforganism（机体）asawhole.Thebrainiscommonlyregardedastheorgansolelyconcernedwiththought,memoryandconsciousness.Allinformationwehaveconcerningtheworldaboutusisconveyedcentrallytothebrainbyanelaborate（精心的详尽的）sensorysystem.,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.（神经胶质）Theneuron（神经元）Theneuronareindependentstructuralunitofthenervoussystemandarefunctionalspecializedforreception,integration（整合）,andtransmissionofcodedinformation（编码）.,NervoussystemIntroduction,RoughgranularEndoplasmicreticulum,SmoothgranularEndoplasmicreticulum,Microtubule,Schwannscell,Myelinsheath,Lysosomes,Lipofuscin脂褐质,dendrite,Eachneuronpossessesanucleatedcellbodyandtwotypesofprocesses(突起),anneuron,whichconductsimpulseawayfromthecellbody,andoneormoredendrites（树突）thatconductsimpulsestowardsthecellbody.Bothoftheseprocessesshowmarkedmorphological（形态学的）difference.Thecellbodyservesasmetabolic（代谢的）centeroftheentireunitandconsistsofalarge,pale（灰白的）nucleus（胞核）andcytoplasm（细胞浆）(perikaryon).,NervoussystemIntroduction,Thestructuresoftheneuron,Thenuclearenvelopeisdouble-layeredmembranewithnumerouspores（小孔）.Thechromatin（染色质）consistsmostlyoflargemoleculesofdeoxyribonucleicacid(DNA).Thenucleolus（核仁）occupiesaprominentpositioninthenucleus,whichisrichinribonucleicacid(RNA).Asinallcells,thenucleusengagesinmarkeddegreeofproteinsynthesis（蛋白质合成）.Theorganelles（细胞器）containedwithinthecytoplasm（细胞质你）arecommontoothercellsinthebody,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（颗粒状的）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,From10200um,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,Nervecel