NERVOUS SYSTEM: AUTONOMIC NERVOUS SYSTEM Anat 35... · The Autonomic Nervous System •“Involuntary” •Function to modulate ongoing automatic activities •Effectors (target

NERVOUSSYSTEM:AUTONOMICNERVOUSSYSTEM

HumanAnatomyUnit4

InAnatomyToday

FunctionalOverviewoftheNervousSystem

TheAutonomicNervousSystem• “Involuntary”• Functiontomodulateongoingautomaticactivities• Effectors(targettissues)– smoothmuscle– cardiacmuscle– glands

• Functionalexamples:– heartrate– ventilation– digestivetractactivity

ANSisaTwoNeuronSystem

• Preganglionicfibers– exittheCNSandterminateontoautonomicganglia

• Postganglionicfibers– exittheautonomicgangliaandterminateontothetarget

MotorNeuronSystems

ComponentsandSubdivisionsoftheANS

• Sympatheticdivision– Fightorflight– Preganglionic fibers

emergefromT1-L2– Postganglionicneurons

emergefromsympatheticchainganglia

• Parasympatheticdivision– Restandrepose– Preganglionic fibers

emergefrompons,medulla,S2-S4

– Postganglionicneuronswithineffector

ComponentsandSubdivisionsoftheANS

OrganizationoftheSympatheticDivision

SympatheticDivision• Sympatheticchain– Location:eithersideofvertebralcolumn– Innervateeffectorsinbodywall,insidethoraciccavity– preganglionicfiberssynapseonpostganglionicfibersveryclosetotheCNSandfarawayfromeffectororgans

• Collateralganglia– Location:betweensympatheticchainandeffector

• Adrenalmedulla– Sympatheticpreganglionicneuronsenteradrenalmedullaandstimulatepostganglionicneurons

– Cellsrespondandreleaseadrenalin(80%epinephrine,20%norepinephrine)

AnatomicalDistributionofSympatheticPostganglionicFibers

CollateralGanglia• Celiacganglion

– Stomach,duodenum,liver,pancreas,spleen,gallbladder

• Superiormesentericganglion– Smallintestines,beginning

oflargeintestines• Inferiormesenteric

ganglion– Kidney,bladder,

reproductiveorgans,largeintestines

AdrenalMedulla

OrganizationoftheParasympatheticDivision

ParasympatheticDivision

• Involvescranialnerves:III,VII,IXandX,S2-S4• Innervatesvisceralorgans• PreganglionicfiberssynapseonpostganglionicfibersfarawayfromtheCNSandwithineffectororgans

AnatomicalDistributionofParasympatheticPostganglionicFibers

DualInnervation

LevelsofAutonomicControl