Bio 207 Exam 2 Questions And Answers With Verified Study Solutions

Bio 207 Exam 2
et et et




Whatetisetmeantetbyettheettermet"restingetmembraneetpotential"?etHowetisetitetma
intained?et-etcorrectetanswer✔ ✔
RestingetmembraneetpotentialetisetwhenettheetequilibriumetpotentialetofetaetN
a+/K+etpumpetisetbetweenet-65etandet-85.et(-90mVetforetK+,et+60mVetforetNa+)


ItetisetmaintainedetbyettheetNa+/K+etpumpetbutetisetgeneratedetbyettheetunequalet
distributionetofetions.


Restingetmembraneetpotentialetisetcloseettoettheetequilibriumetpotentialetofetwhi
chetionet(EK+etoretENa+)?et-etcorrectetanswer✔ ✔
ItetisetmuchetcloserettoettheetK+etequilibriumet(-
90mV)etbecauseettheetmembraneetisetmoreetpermeableettoetK+


WhatetisettheetroleetofetNa+/K+etpumpetinetmaintainingetmembraneetpotential?et
Whatetisettheetroleetofetfixedetanions?et-etcorrectetanswer✔ ✔
TheetpumpsetactivelyetbringetinetK+,etwhichetpasseseteasilyetthroughettheetme
mbraneetandetmakesettheetcelletinterioretnegative


Negativeetanionsetinsideettheetcelletattractetcationsetoutsideettheetcell


Nameettheetsixettypesetofetglialetcellset-etcorrectetanswer✔ ✔
Schwannetcells

,Astrocytes
Microglia
Oligodendrocyte
Ependymal
Satelliteetcells


WhatetareettheetfunctionsetofetSchwannetcellsetinetnerveetconductionetandetnerve
etregenerationetfollowingetinjury? et-etcorrectetanswer✔ ✔
Schwannetcellsetformetmyelinetsheathsetaroundetperipheraletaxons.etMyelina
tedetaxonsetconductetimpulsesetmoreetrapidly.et


WhenetpartetofetaetPNSetnerveetisetsevered,ettheetSchwannetcelletsurvivesetandetf
ormsetaetregenerationettube.etTheettubeetreleasesetchemicalsetthatetattractetgrow
ingetaxonetandetguidesetregrowingetaxonettoetsynapticetsite.


Whatetareettheetfunctionsetofetoligodendrocytes?et-etcorrectetanswer✔ ✔
TheyetproduceetmyelinetsheathsetaroundetaxonsetinettheetCNS.etOneetoligode
ndrocyteetsendsetextensionsettoetseveraletaxons.


Whatetareettheetfunctionsetofetastrocytes?et-etcorrectetanswer✔ ✔
TakeetupetK+etfromettheetextracellularetenvironmentettoetmaintainetionicetenv
ironmentetforetneurons.etTakeetupetextraetneurotransmittersetreleasedetfrometax
onetendings;etTheetchemicalsetareetrecycled.etHelpetformettheetblood-
brainetbarrieretbyetproducingettightetjunctionsetinetbrainetcapillaries.etEnd-

, feetetaroundetcapillariesettakeetupetglucoseetfrometbloodetforetuseetbyetneuronsett
oetmakeetATP.


Describeetionetgatingetinetaxonset-etcorrectetanswer✔ ✔
Changesetinetmembraneetpotentialetareetcontrolledetbyetchangesetinettheetflow
etofetionsetthroughetionetchannels.



K+ethasettwoettypesetofetchannels:
Notetgatedet(alwaysetopen);etsometimesetcalledet"leaky"etK+etchannels
et



Voltage-
et


gatedetK+etchannels;etopenetwhenetaetparticularetmembraneetpotentialetisetreac
hed


Na+ethasetonlyetvoltage-gatedetchannelsetthatetareetclosedetatetrest.
TheetmembraneetisetlessetpermeableettoetNa+etatetrest.


Whatethappensetduringetactionetpotential?et-etcorrectetanswer✔ ✔
Whenetmembraneetpotentialetisetdepolarizedettoet-
55mV,etgatesetopenetthatetletetinetNa+.etNa+etpassesetthroughettheetmembraneeta
ndettheetmembraneetpotentialetthereforeetgetsetcloserettoettheetsodiumetpotential
.etAtet+30mV,ettheetsodiumetgatesetcloseetandettheetpotassiumetonesetopenettoetre
leaseetK+.etRepolarizationetgetsettheetrestingetpotentialetbacketdownettoet-
85mV,etwhereetitetisetthenetstabilizedetbyetNa+/K+etpumps.