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Lecture6
OtherSensorySystems
Cogs17*UCSD
VestibularSystem
Balance
VestibularSysteminInnerEar
InnerEar
Hearing
VestibularSystem
Hearing
Semicircularcanals
Otolith Organs
Semi-CircularCanals- ROTATIONAt0facingX…
X
Y
Z
Semi-CircularCanals
TubesfilledwithK+richEndolymph
HairCells(VestibularReceptorCells)
intheAmpullaeatthebaseofthecanals
Cristaampullaris
Ampulla
Semi-CircularCanals
Cillia of
HairCellsembeddedin
gelatonous Cupula,arebentbyflowofEndolymph
inAmpulla
Cristaampullaris
Semi-CircularCanals
Cillia of
HairCellsembeddedin
gelatonous Cupula,arebentbyflowofEndolymph
inAmpulla
Cristaampullaris
Atstart ofrotation,fluidlagsbehind
Atend ofrotation,fluidovershoots
AsfluidpushesagainstCrista,oneway,ortheother,HairCells firemore,orless
Semi-CircularCanals
Cillia of
HairCellsembeddedin
gelatonous Cupula,arebentbyflowofEndolymph
inAmpulla
Cristaampullaris
Atstart ofrotation,fluidlagsbehind
Atend ofrotation,fluidovershoots
AsfluidpushesagainstCrista,oneway,ortheother,HairCells firemore,orless
Cellsonlyreactatonset andoffset ofmotion,
(oracceleration&deceleration),not duringsteadyrotation
SystemdetectsCHANGE
VestibularHairCalls
• VerysimilartoHairCellsinauditorysystem
• HighconcentrationofPotassium(K+)
inEndolymph
• K+in,Ca++in,Neurotransmitter
released
• BUToneimportantdifference...
VestibularHairCells
…haveSpontaneous firing,inabsenceofinputThatis,whennorotation,HairCellreleasesa
baserateofneurotransmitter
LESSneurotransmitter
isreleased
Bendcilliaotherway,
MOREneurotransmitter
isreleased
Bendcillia oneway,
Baserate
Otolith Organs- HEADTITLT
TheMaculamadeoftheUtricle
andtheSaccule
HairCellslinethewallsofthese
Endolymph-filledchambers
Otolith Organs- HEADTITLT
Otolith
Whicheverangleyoutiltyourhead,someOtoliths willweighdownthecillia ofsomeHairCells
Again,bendoneway,firemore,bendotherway,fireless
Otoliths"EarStones"
calcium-carbonatecrystals,sitingelatinousmaterial
inwhichHairCells areembedded
Whenheadisupright,havebaserateoffiring
Andagain,VestibularSystem
onlydetectsCHANGE
Otolith Organs- HEADTITLT
Notethat AccelerationandDeceleration havesameeffectasTiltBackwardandTiltForward,respectively
So,Otolith Organsdetectstart/stopoflocomotion
aswellasheadtilt
VestibularPathwayHairCells
VestibularGanglion
8thCranialNerve VestibularNuclei(Medulla)
Cerebellum
SuperiorColliculus
CranialNerves3,4,6
(EyeMovements)
TemporalLobe(???)
SpinalCord/BrainStem
(Posture)
Coordinatew/visualmotioninfo
MotionSickness
OccurswhenVestibular andVisual systemsarenotcoordinatedasexpected
Inspace
Inacar
SomatosensorySystem
TheSkinSenses
SomatosensoryReceptors
Pain&TemperatureReceptors
FreeNerveEndings
Mechano-Receptors
EncapsulatedNerveEndings
FreeNerveEndings
Pain&TemperatureReceptors
FreeNerveEndings
TEMPERATURE:
Thermoreceptors(Warm-best&Cool-Best)
PAIN:
Nociceptor(Pain,Itch,Extremesoftemp)
SomatosensoryReceptors
Mechano-Receptors
EncapsulatedNerveEndings
ForTouchand
Proprioception(internalmuscle
andorganmovements)
Mechano-Receptors
SmallReceptiveField1:1forDetails
LargeReceptiveFieldConvergent
Meissner'sCorpusclesSlippage
Merkel'sDiscs
ReadingBraille
PacinianCorpusclesBending
RuffinniEndingsPosture
offon
on off
FastAdapting
SlowAdapting
AcrossFiberCoding
89o73o 105o
Codefor89o :WB =CB
Temperature
ReceptorRespo
nse
Cool-BestReceptors
Warm-BestReceptors
CB WB
Codefor73o:WB <CB
Codefor105o :WB >CB
Thermoreceptors
"PhysiologicalZero"
So,itstherelativeproportionofactivityacrossfibers
thatcodesforagiventemperature
AcrossFiberCoding
89o73o 105o
89o
Temperature
Temperature
ReceptorRespo
nse
ReceptorRespo
nse
Cool-BestReceptors
Warm-BestReceptors
CB WB
CB
WB Afteradaptingtoicecoldwater
89o ismiscoded as105o
(WB >CB)
Feelswarm!
Thermoreceptors
Cool-BestReceptortemporarilyadapted
T
EncapsulatedNerveEnding
BRAIN
SPINALCORD
LeftVPN
Medulla
MedialLemniscal
Left CortexS1
MedialLemniscalPathway
FreeNerveEnding
SpinalThalamicPathway
Cross-overInSpinalCord
Cross-overInMedulla
EnterthroughDorsalHornofSpinalCord
SomatosensoryPathways
VPN(VentralPosteriorNucelus)
ofThalamus
T
EncapsulatedNerveEnding
VPNRightLeftVPN
Medulla
MedialLemniscal
Left CortexS1 S1CortexRight
FreeNerveEnding
SpinalThalamicPathway
Cross-overInSpinalCord
Cross-overInMedulla
MedialLemniscalPathway
Brown-SequardSyndrome
Damagetoonlyonesideofspinalcord>>
LossofTouch onIPSI-Lateralside
LossofTemp/PainonCONTA-Lateralside
BRAIN
SPINALCORD
SomatosensoryPathways
VPNVPN
MedullaMedial
Lemniscal
CortexS1 S1Cortex
TSpinalThalamic
PathwayMedialLemniscal
Pathway
BRAIN
SomatosensoryPathways
T
S2CortexCortexS2 CorpusCallosum
FromS2 on,infofromboth
sidesiscombined
Somatonsensory CortexPENFIELDMAP
TOPOLOGICALMAPS(PreservetheSpatialRelationships
of sensorysurface)
MAGNIFICATION(Hands&Mouth
Highacuity=detaildiscrimination)
T
Itch
Scratch
Gate1
BRAIN
SPINALCORD
LeftVPN
LCortexS1
GateTheoryofendogenousPAINcontrol
ToMedulla
SGCell
InhibitoryInter-NeuroninSpinalCord
T
Itch
Gate2
BRAIN
SPINALCORD
LeftVPNMidbrain
PAG
HindbrainRaphe
LCortexS1
GateTheoryofendogenousPAINcontrol
Endorphinsreleased
SGCell
InhibitoryInter-NeuroninSpinalCord
GateTheory- InBrainInbrain,
activityalongPainpathways
ProvokesactivityfromEndorphincells
ReceptorsitesonTerminal ofpaincellrespondstoEndorphins
InhibitsreleaseofSubstanceP
GateTheoryofendogenousPAINcontrol
Endorphinsreleased
SubstancePreleased
Gate3
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