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sympatheticnerves

para-sympathetic

nerves

sensorynerves

axons ofmotor nerves

somaticsubdivision

(motor functions)

autonomicsubdivision

(visceralfunctions)

peripheral nervous system

CENTRALNERVOUSSYSTEM

brain

spinalcord

sympatheticnerves

para-sympathetic

nerves

sensorynerves

axons ofmotor nerves

somaticsubdivision

(motor functions)

autonomicsubdivision

(visceralfunctions)

peripheral nervous system

CENTRALNERVOUSSYSTEM

brain

spinalcord

NervousSystemPartIFunctionsoftheNervousSystem Sensoryinputgatheringinformation

Tomonitorchangesoccurringinsideandoutsidethebody Changes=stimuli

Integration Toprocessandinterpretsensoryinputanddecideifactionis

needed Motoroutput

Aresponsetointegratedstimuli Theresponseactivatesmusclesorglands

StructuralClassification Centralnervoussystem(CNS)

Brain Spinalcord

Peripheralnervoussystem(PNS) Nervesoutsidethebrainandspinalcord

Spinalnerves Cranialnerves

FunctionalClassificationofthePeripheralNervousSystem Sensory(afferent)division

Nervefibersthatcarryinformationtothecentralnervoussystem

Motor(efferent)division Nervefibersthatcarryimpulsesawayfromthecentral

nervoussystem

Twosubdivisions Somaticnervoussystem=voluntary Autonomicnervoussystem=involuntary

NervousTissue:SupportCells SupportcellsintheCNSaregroupedtogetherasneuroglia Function:tosupport,insulate,andprotectneurons Astrocytes

Abundant,starshapedcells Braceneurons Formbarrierbetweencapillariesandneurons Controlthechemicalenvironmentof

the

brain

Microglia Spiderlikephagocytes Disposeofdebris

Ependymalcells Linecavitiesofthebrainandspinalcord Circulatecerebrospinalfluid

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Oligodendrocytes Wraparoundnervefibersinthecentralnervoussystem Producemyelinsheaths

Satellitecells Protectneuroncellbodies

Schwanncells Formmyelinsheathintheperipheralnervoussystem

NervousTissue:Neurons Neurons=nervecells Cellsspecializedtotransmitmessages

Majorregionsofneurons Cellbodynucleusandmetabolic

centerofthecell

Processesfibersthatextendfromthecellbody

Dendritesconductimpulsestowardthecellbody

Axonsconductimpulsesawayfromthecellbody

Axonsendinaxonalterminals Axonalterminalscontainvesicleswith

neurotransmitters

Axonalterminalsareseparatedfromthenextneuronbyagap

Synapticcleftgapbetweenadjacentneurons

Synapsejunctionbetweennerves Myelinsheathwhitish,fattymaterialcovering

axons

Schwanncellsproducemyelinsheathsinjellyrolllikefashion NodesofRanviergapsinmyelinsheathalongtheaxonNeuronCellBodyLocation Mostneuroncellbodiesarefoundinthecentralnervoussystem

Graymattercellbodiesandunmyelinatedfibers Nucleiclustersofcellbodieswithinthewhitematterofthecentral

nervoussystem

Gangliacollectionsofcellbodiesoutsidethecentralnervoussystem

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FunctionalClassificationofNeurons Sensory(afferent)neurons

CarryimpulsesfromthesensoryreceptorstotheCNS Cutaneoussenseorgans Proprioceptorsdetectstretchortension

Motor(efferent)neurons Carryimpulsesfromthecentralnervoussystemtoviscera,muscles,orglands

NeuronClassification Interneurons(associationneurons)

Foundinneuralpathwaysinthecentralnervoussystem

Connectsensoryandmotorneurons

NervousSystemPartIIFunctionalPropertiesofNeurons Irritability

Abilitytorespondtostimuli

Conductivity Abilitytotransmitan

impulse

NerveImpulses Restingneuron

Theplasmamembraneatrestispolarized Fewerpositiveionsareinsidethecellthanoutsidethecell

Depolarization Astimulusdepolarizestheneuronsmembrane Adepolarizedmembraneallowssodium(Na+)toflowinsidethemembrane

Repolarization Potassiumionsrushoutoftheneuronaftersodiumionsrushin,whichrepolarizesthemembrane Thesodiumpotassiumpump,usingATP,restorestheoriginalconfiguration

Theexchangeofionsinitiatesanactionpotentialintheneuron

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Axon

terminal

Vesicles

Synapticcleft

Actionpotentialarrives

Synapse

Axon oftransmittingneuron

Receivingneuron

Neurotrans-mitter is re-

leased intosynaptic cleft

Vesiclefuses with

plasmamembrane

Synaptic cleftNeurotransmittermolecules

Ion channelsReceiving neuron

Transmitting neuron

Stimulus at distalend of neuron

Skin Spinal cord(in cross section)

Interneuron

Receptor

Effector

Sensory neuron

Motor neuron

Integrationcenter

(a)

Actionpotential Iftheactionpotential(nerveimpulse)starts,itispropagatedovertheentireaxon Impulsestravelfasterwhenfibershaveamyelinsheath

TransmissionofaSignalatSynapse Impulsesareabletocrossthesynapsetoanothernerve

Neurotransmitterisreleasedfromanervesaxonterminal Thedendriteofthenextneuronhasreceptorsthatarestimulatedbytheneurotransmitter Anactionpotentialisstartedinthedendrite

TheReflexArc Reflexrapid,predictable,andinvoluntaryresponsetoastimulus

Occursoverpathwayscalledreflexarcs Reflexarcdirectroutefromasensoryneuron,toaninterneuron,toaneffector

TypesofReflexesandRegulation Somaticreflexes

Activationofskeletalmuscles Example:Whenyoumoveyourhandawayfromahotstove

Autonomicreflexes Smoothmuscleregulation Heartandbloodpressureregulation Regulationofglands Digestivesystemregulation

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NervousSystemPartIIIRegionsoftheBrain Cerebralhemispheres(cerebrum) Diencephalon Brainstem Cerebellum

RegionsoftheBrain:Cerebrum CerebralHemispheres(Cerebrum)

Paired(leftandright)superiorpartsofthebrain Includesmorethanhalfofthebrainmass Thesurfaceismadeofridges(gyri)andgrooves

(sulci)

Lobesofthecerebrum Fissures(deepgrooves)dividethecerebruminto

lobes

Surfacelobesofthecerebrum Frontallobe Parietallobe Occipitallobe Temporallobe

Specializedareasofthecerebrum Primarysomaticsensoryarea

Receivesimpulsesfromthebodyssensoryreceptors

Locatedinparietallobe Primarymotorarea

Sendsimpulsestoskeletalmuscles Locatedinfrontallobe

Brocasarea Involvedinourabilitytospeak

Cerebralareasinvolvedinspecialsenses Gustatoryarea(taste) Visualarea Auditoryarea Olfactoryarea

Interpretationareasofthecerebrum Speech/languageregion Languagecomprehensionregion Generalinterpretationarea

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Layersofthecerebrum Graymatterouterlayerinthecerebralcortex

composedmostlyofneuroncellbodies

Whitematterfibertractsdeeptothegraymatter Corpuscallosumconnectshemispheres

Basalnucleiislandsofgraymatterburiedwithinthewhitematter

RegionsoftheBrain:Diencephalon Sitsontopofthebrainstem Enclosedbythecerebralhemispheres Madeofthreeparts

Thalamus Hypothalamus Epithalamus

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Thalamus Surroundsthethirdventricle Therelaystationforsensoryimpulses Transfersimpulsestothecorrectpartofthecortexforlocalizationandinterpretation

Hypothalamus Underthethalamus Importantautonomicnervoussystemcenter

Helpsregulatebodytemperature Controlswaterbalance Regulatesmetabolism

Animportantpartofthelimbicsystem(emotions) Thepituitaryglandisattachedtothehypothalamus

Epithalamus Formstheroofofthethirdventricle Housesthepinealbody(anendocrinegland) Includesthechoroidplexusformscerebrospinalfluid

RegionsoftheBrain:BrainStem Attachestothespinalcord Partsofthebrainstem

Midbrain Pons Medullaoblongata

Midbrain Mostlycomposedoftractsofnervefibers Hastwobulgingfibertracts

cerebralpeduncles

Hasfourroundedprotrusionscorporaquadrigemina

Reflexcentersforvisionandhearing Pons

Thebulgingcenterpartofthebrainstem Mostlycomposedoffibertracts Includesnucleiinvolvedinthecontrolof

breathing

MedullaOblongata Thelowestpartofthebrainstem Mergesintothespinalcord Includesimportantfibertracts Containsimportantcontrolcenters

Heartratecontrol Bloodpressureregulation Breathing Swallowing Vomiting

ReticularFormation Diffusemassofgraymatteralongthebrain

stem

Involvedinmotorcontrolofvisceralorgans Reticularactivatingsystem(RAS)playsarole

inawake/sleepcyclesandconsciousness

RegionsoftheBrain:Cerebellum Twohemisphereswithconvolutedsurfaces Providesinvoluntarycoordinationofbodymovements