Sensory Systems I: Touch, Taste, and Smell

Animalsensorysystems1 Lecture 4 ma
cortex corteses governyoursenses communicate w otherpartstohelpw decisionmaking
sensoryreceptors extraspecialproteins insensorycells embeddedinsensoryorgans
detectstimuli light chemicals pressure temperature sound receptor
cells
sensorytransductionistheconversionof physicalor chemicalstimuliintonerveimpulses actionpotential




moleculespecialized
either fireactionpotentials themselves or synapsewithotherneuronsthatfireactionpotentials whicharethentransmittedtoaus
inmanycases stimulicancause ionchannels in membrane to openindirectly causesignaltransduction insensoryneurons
olfactionomen environmental stimulidirectlycausessignaltransduction
sensorytransduction chemoreceptors

a chemoreceptors detect chemicalsbybindingspecificmolecules tospecificprotein receptorson cell
the membrane




tasteNatin
environmentsignal
changes ionHow changesmembranepotential s startsa neuralsignal
to
openion ligand molecule in chemoreceptionoften notalways bindsto a GPCRwhichthen
channelprotein
activates a secondary messengerpathwaythatdepolarizesthecell unlikeligandgatedchannels
animalsdetectkeymolecules o2co2 glucose aminoacids
receptorcellis chemoreceptionunderlies smell
depolarized

moleculesbindtoproteinreceptoron a tastereceptor proteinreceptor changesconformation triggersopeningofwat
channelsthrough a coupledsignaltransductionpathways influxofNat depolarizescellreceptormembrane
insometastereceptorsensorycells no aptires but depolarization travels farenoughto triggerreleaseof
neurotransmitters sosignaltransductioncomplete
sensorytransduction mechanoreceptors
pressure
mechanoreceptorsrespondto physicaldeformationsoftheirmembraneproducedbytouch
stretch pressure motion and sound
deformationopensionchannels causingdepolarizationand neurotransmitter release
ex ears catwhiskers stretchreceptors inmusclesthatinfluencethemuscle's motoractivation
mechanoreception oftactileinformation


transductioncuticlecell
a
touch
distinct morphologically
vibration andtension pressure
toprovideinformationtothecnsabout
mechanoreceptors specialized



is
Meissner's corpuscles Pacinancorpuscles disks andRuffini's corpuscles
Merkel's
receptorsarecollectivelylow
these threshold highsensitivity

depolarizedsensory all lowthreshold mechanoreceptors areinnervatedbyrelativelylarge myelinatedaxons ensuring
rapidsignal
transduction photoreceptors
sensorydetectors in eyesareliantdetecting photoreceptors



themlightxsignal
vertebrates photoreceptors respondtoindividualphotonsoflight
energybyclosingNatchannels
to
ion causingthemtobehyper
close
polarized
channelcell inhibitthefiringrate ofotherneurons intheeyeratherthanexciting
is
hyperpolarizedprotein
receptorvariety
of sensory
receptorsThermoreceptors
receptors nottested
infish respondtoheat cold helpto
receptorincontactw controlmetabolism andpatterns



skinelectro
environment ofbloodflow
nociceptors nottested regulatingbodytempbyregulating
painreceptors levelsofheatlossandgain
APtobrain spinalcord hypothalamus
external internal in