Handouts - Nervous System and Brain Parts 1 - 3
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Transcript of Handouts - Nervous System and Brain Parts 1 - 3
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8/7/2019 Handouts - Nervous System and Brain Parts 1 - 3
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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