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PNB 2274 Exam 2| questions and answers correct and verified A+ $14.49   Add to cart

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PNB 2274 Exam 2| questions and answers correct and verified A+

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  • PNB 2274

PNB 2274 Exam 2| questions and answers correct and verified A+ Why are cell membranes not conductive? - correct answers-cell membranes insulate the flow of electrical charge. How is the electrical potentials (membrane voltage) measured in a cell? - correct answers-Membrane voltage is always i...

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  • November 6, 2024
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  • 2024/2025
  • Exam (elaborations)
  • Questions & answers
  • PNB 2274
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PNB 2274 Exam 2| questions and answers
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correct and verified A+
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Whylsarelscelllsmembraneslsnotlsconductive?ls-lscorrectlsanswers-
celllsmembraneslsinsulatelsthelsflowlsoflselectricallscharge.
Howlsislsthelselectricallspotentialsls(membranelsvoltage)lsmeasuredlsinlsalscell?ls-lscorrectlsanswers-
Membranelsvoltagelsislsalwayslsinlstermslsoflsinsidelsrelativelstolsoutside:lselectricallspotentialslsarelsmea
suredlsusinglsintracellularlselectrodeslsinsidelsoflscellslswithlsreferencelstolsanlsexternallsgroundlselectro
de.
Atlswhatlspointlsdolswelsgetlsalsbalancelsbetweenlsdiffusionlsandlselectricallscharge?ls-lscorrectlsanswers-
Nernstlsequilibrium
-lsEionx
-
lsthelselectricallspotential/voltagelsatlswhichlsthelsdiffusionallsflowlsoflsanlsionlsonelswaylsislsbalancedlsbylst


helselectrostaticlsattractionlsinlsthelsother.
Atlsequilibriumlswhatlsislsthelsvoltagelslikelsoflsalsmembrane?ls-lscorrectlsanswers-
atlsequilibriumlstherelsislsalsdifferencelsinlscharge
WhatlsislsthelsNernstlsEquation?ls-lscorrectlsanswers-Eionxls=lsRT/zFls([x]out/[x]in)
Whatlsdetermineslsthelsmembranelspotentiallsatlswhichlsanlsionlsislsinlsequilibrium?ls-lscorrectlsanswers-
thelsconcentrationlsgradientlsandlsthelschargelsoflsthelsion
(transporterslswilllsservelstolschangelsconcentrationlsslightlylsandlsthuslseffectlsequilibriumlspotential)
WhatlsarelsthelsonlylsfactorslsoflsthelsnernstlsequationlsthatlswilllschangelsExlsoflsalsparticularlsion?ls-
lscorrectlsanswers-temperaturelsandlsconcentration



Whatlsislsthelslnlsofls1?lsWhylsdoeslsthislsmatter?ls-lscorrectlsanswers-thelslnlsofls1lsislszero
-
lsiflsthelsconcentrationlsoflsthelsparticularlsionlsonlsbothlssideslsoflsthelsmembranelsarelsequal,lsthislspartlso


flsthelsnernstlsequationlsequalslsonelsandlsthereforelstherelsislsnolsnetlsflowlsoflsthelsionlsandlsEx=0
-
lsbecauselswelsarelsconsideringlsonlylsonelsion,lschargelswilllsbelsequallsonlsbothlssideslsoflsthelsmembrane



-lsnolsconc.lsgradientlsorlselectrostaticlsgradient

,Whatlsislsthelslnlsoflsalsnumberlslesslsthanls1?lsWhylsdoeslsthislsmatter?ls-lscorrectlsanswers-
thelslnlsoflsalsnumberlslesslsthanls1lsislsalsnegativelsnumberls
-
lsthislsmeanslsthatlstherelsislsalsgreaterlsconcentrationlsoflsthelsparticularlsionlsinsidelsthelscelllsthanlsoutsi


de
Whatlsislsthelslnlsoflsalsnumberlsgreaterlsthanls1?lsWhylsdoeslsthislsmatter?ls-lscorrectlsanswers-
thelslnlsoflsalsnumberlsgreaterlsthanls1lsislsalspositivelsnumber
-
lsthislsmeanslsthatlstherelsislsalsgreaterlsconcentrationlsoflsthelsparticularlsionlsoutsidelsthelscelllsthanlsinsi


de
WhatlsarelsthelsNernstlsvaluesls(Vm)lsforlspotassium,lschloride,lssodium,lsandlscalcium?ls-
lscorrectlsanswers-Ek=ls-90



Ecl=ls-70
Ena=ls+60
Eca=ls+130
Whatlsarelsthelsrelativelsconcentrationslsoflspotassium,lssodium,lschloride?ls-lscorrectlsanswers-
K+lsislshigherlsinsidels
Na+lsislshigherlsoutside
Cl-lsislshigherlsoutside
WhylsdolswelsuselsthelsGHKlsequation?ls-lscorrectlsanswers-
celllsmembraneslsarelspermeablelstolsmorelsthanlsonelsionlsatlsrest
-lsthelsVmlsthereforelsislsalsweightedlsaveragelsoflsthelsExlsforlseachlspermeablelsionls
-ls"z"lsislsnowls1
-ls"P"lsislsalsmeasurelsoflsthelspermeability
Whylsislsthelsratiolsforlsthelspermeabilitylsoflschloridelsreversed?ls-lscorrectlsanswers-
Cllsislsalsnegativelsion
WhatlsislsthelsGHKlsequationlslikelsforlsalsrestinglsmembrane?ls-lscorrectlsanswers-
thelspermeabilitylstolssodiumlsislszerolsinlsalsrestinglsmembranelsthereforelsPnalscanlsbelseliminatedlsfro
mlsthelsequationls
-lsonlylsK+lsandlsCl-lsdictatelsthelsmembranelspotentiallsatlsrest
-lsthislsislswhylsVmlsatlsrestlsislscloselstolsEklsbecauselsthelsmembranelsislsmostlspermeablelstolspotassium

, WhatlsislsthelsrolelsoflsK+lsleaklschannels?ls-lscorrectlsanswers-
K+lsleaklschannelslsmaintainlsthelsrestinglspotential
Whatlsarelsgradedlspotentialslsandlswherelsarelsgradedlspotentialslsimportant?ls-lscorrectlsanswers-
gradedlspotentialslshappenlsinlsthelsdendriteslsoflsneuronslsandlsthelsmotorlsendplatelsoflsmotorlsneuro
ns
-
lsgradedlspotentialslsarelsthelsinputlscominglsintolsdendriteslsandlscanlsbelsdepolarizinglsorlshyperpolarizi


ng
-
lsdecreaselsinlsstrengthlsaslstheylsspreadlsoutlsfromlsthelspointlsoflsoriginls(decrement)ls=lsdecreaselsinlsstr


engthlsoflsEPSP
-lscanlsbelsinvolvedlsinlstemporallssummationlsandlsspatiallssummation
-lsdictatedlsbylsligandlsgatedlschannels
Whatlsislsthelsdefinitionlsoflsanlsactionlspotential?lsWherelsdoeslsanlsactionlspotentiallsoccur?ls-
lscorrectlsanswers-anlsactionlspotentiallsoccurslsinlsthelsaxonsls



-lsarelsall-or-nothingls(mustlsreachlsthresholdlsmembranelspotentiallstolshavelsanlsactionlspotential)
-lsmusclelscontractionslsandlsthelsreleaselsoflshormoneslsarelsexampleslsoflsactionlspotentials
-lsdictatedlsbylsvoltagelsgatedlschannels
Whatlsarelsthelsdifferenceslsbetweenlsdepolarization,lsrepolarization,lsandlshyperpolarization?ls-
lscorrectlsanswers-


depolarization:lschanginglsmembranelspotentiallstolsbelsmorelspositivels(openinglsoflsNa+lschannels)ls
repolarization:lsreturninglsmembranelspotentiallstowardslsrestlspotentialls(K+lschannelslsopen)ls
hyperlspolarization:lschanginglsmembranelspotentiallstolsbelsmorelsnegativels(K+lschannelslsarelsremain
inglsopenlslongerlsthanlssodiumlschannelslswhichlscloselsquickly)
Whatlsislstemporallssummation?ls-lscorrectlsanswers-twolssub-
thresholdlsgradedlspotentialslswilllsNOTlsinitiatelsanlsactionlspotentiallsiflstheylsarelsfarlsapartlsinlstime
twolssublsthresholdlspotentialslsarrivelsatlstriggerlszonelsinlsalsshortlsperiodlsoflstimelssumlstolsinitiatelsanlsa
ctionlspotential
Whatlsislsspatiallssummation?ls-lscorrectlsanswers-
summationlsoflsseverallssublsthresholdlssignalslsresultslsinlsanlsactionlspotentialls

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