医学英语-中枢神经系统

NervousSystem-CNSpart1,StudyGuideSUMC2011-212,/group/hopes/cgi-bin/wordpress/2010/06/the-hopes-brain-tutorial-text-version/,Forfurtherreadingpleaseseefollowingwebpage:,Onewaytoclassifyneuronsisbythenumberofextensionsthatextendfromtheneuronscellbody(soma).,Bipolarneuronshavetwoprocessesextendingfromthecellbody(examples:retinalcells,olfactoryepitheliumcells).,Pseudo-uni-polarcells(example:dorsalrootganglioncells).Actually,thesecellshave2axonsratherthananaxonanddendrite.Oneaxonextendscentrallytowardthespinalcord,theotheraxonextendstowardtheskinormuscle.,Multipolarneuronshavemanyprocessesthatextendfromthecellbody.However,eachneuronhasonlyoneaxon(examples:spinalmotorneurons,pyramidalneurons,Purkinjecells).,Typesofneurons.,Neuronscanalsobeclassifiedbythedirectionthattheysendinformation:,Sensory(orafferent)neurons:sendinformationfromsensoryreceptors(e.g.,inskin,eyes,nose,tongue,ears)TOWARDthecentralnervoussystem.Motor(orefferent)neurons:sendinformationAWAYfromthecentralnervoussystemtomusclesorglands.Interneurons:sendinformationbetweensensoryneuronsandmotorneurons.Mostinterneuronsarelocatedinthecentralnervoussystem.,Typesofneurons.,Asingleneuronconsistof:CELLBODY:isthemetaboliccenteroftheneuron,containstheNucleusandMitochondrion.DENDRITES:conveyincomingmessagestothecellbody.AXONHILLOCK:aconelikeregionfromwhereanaxonarises.AXONS:generatesnerveimpulsesandtopicallyconductthemawayfromthecellbody.Anerveisagroupofaxons”.Presynapticterminals:Theswollen,distalendofanaxon;containsaneurotransmittersubstancewithinsynapticvesicles.Alsocalledsynapticending.,AxonsTakeinformationawayfromthecellbodySmoothSurfaceGenerallyonly1axonpercellNoribosomesCanhavemyelinBranchfurtherfromthecellbody,DendritesBringinformationtothecellbodyRoughSurface(dendriticspines)UsuallymanydendritespercellHaveribosomesNomyelininsulationBranchnearthecellbody,Thereareseveraldifferencesbetweenaxonsanddendrites:,NEUROGLIA