autonomic nervous system...autonomic nervous system physiology unit 2 in physiology today peripheral...
TRANSCRIPT
AUTONOMICNERVOUSSYSTEM
PhysiologyUnit2
InPhysiologyToday
PeripheralNervousSystemOrganization
SomaticDivision• SingleneuronbetweenCNS
andskeletalmusclecells• Innervatesskeletalmuscle• Canonlyleadtomuscle
excitation
AutonomicDivision• Twoneuronsystem
betweenCNSandeffectororgans
• Innervatessmoothmuscle,cardiacmuscle,glands
• Canbeeitherexcitatoryorinhibitory
AutonomicNervousSystem
• 2neuronsinseriessynapsingataganglia
• Preganglionicneuron– CNStoganglion
• Postganglionicneuron– Gangliontoeffector
SympatheticDivision• FightorFlightresponse• Increasesactivityunderconditionsofphysicalorphysiologicalstress
• Allresourcesforphysicalexertionareactivated– HRincreases– BPincreases– Bloodflowtoskeletalmuscles,heartandbrainincreases
– Liverreleasesglucose– Pupilsdilate– GItractactivityisdampened– Bloodflowtotheskinisreduced
SympatheticDivisionThoracolumbarDivision
• SympatheticneuronsexittheCNSfromthethoracicandlumbarregionsofthespinalcord
• Gangliaarrangedasthesympathetictrunks– Closetothespinalcord– 2chainsoneithersideofthespinalcord
ParasympatheticDivision
• Restanddigestresponse• Homeostaticfunctionsarepredominant
ParasympatheticDivisionCraniosacralDivision
• PreganglionicneuronsexittheCNSfromthebrainstemandsacralregionsofthespinalcord
• Parasympatheticganglialiewithinorveryclosetotheeffectororgansthatthepostganglionicneuronsinnervate
ActivationPatternsoftheDivisions
• SympatheticDivision–Moredivergenceofpreganglionicneurons– Tendstorespondasasingleunit– Increasedsympatheticactivitytendstooccurbodywide
• ParasympatheticDivision– Lessdivergenceofpreganglionicneurons– Specificorgansareactivatedinapatternthatisdependentoneachphysiologicalresponse
NeurotransmittersoftheANS• PreganglionicneuronsreleaseACh• Postganglionicneurons– SympatheticdivisionreleaseNE– ParasympatheticdivisionreleaseACh
• Cotransmittersreleasedbypreganglionicneuronswiththeprimaryneurotransmitteratmanyautonomicganglia– ATP,dopamine,neuropeptides
• Postganglionicneurons– Nitrousoxideforsmoothmuscledilation
AdrenalMedulla
• Postganglionicneuronsthatinnervatetheadrenalmedulladonotdevelopaxons
• Theformtheendocrinegland,theadrenalmedulla
• Onceactivatedbythesympatheticpreganglionicneuron,thecellsoftheadrenalmedullarelease80%Epi,20%NEintotheblood
TransmittersofthePeripheralNervousSystem
DualInnervation
• Theheart,manyglandsandsmoothmuscleareinnervatedbybothdivisionsoftheANS
• Opposingeffects• Divisionsareusuallyactivatedreciprocally– Sympatheticactivityincreases– Parasympatheticactivitydecreases– Visversa
• Providesprecisecontroloftheeffector
CooperativeControl• BothdivisionsoftheANS
operatetogether• Autonomicresponses
resultfromtheregulatedinteractionsofboththeparasymapathetic andsympatheticdivisions
• Autonomicresponsesusuallyoccurwithoutawarenessorconsciouscontrol(autonomous)