BIOLl 322l BIOL322l Modulel 2:l Latestl

BIOLl 322/l BIOL322l Modulel 2:l (Latestl

2026/l 2027l Update)l 100%l Verifiedl Questionsl &l Answersl |l Gradel A

QUESTION

Rapidl depolarizationl followedl byl thel overshoot,l whenl thel membranel potentiall becomesl positivel representsl whichl phasel ofl anl AP?

Answer:l

Risingl phase

QUESTION

Rapidl repolarizationl followedl byl thel undershoot,l whenl thel membranel potentiall hyperpolarizesl pastl restl representsl whichl phasel ofl anl AP?

Answer:l

Thel fallingl phase

QUESTION

Whatl causesl thel risingl phase?l Howl fastl dol thesel gatesl open?

Answer:l

Thel openingl ofl voltage-gatedl sodiuml channels;l immediatelyl open

QUESTION

Whatl twol thingsl causel thel fallingl phasel ofl anl APl tol occur?

Answer:l

1.l Inactivationl ofl sodiuml channels 2.l Openingl ofl potassiuml channels

• / 3

QUESTION

Howl longl doesl itl takel sodiuml channelsl tol inactivate?

Answer:l

Approximatelyl 1l msec

QUESTION

Whatl happensl tol sodiuml channelsl oncel membranel potentiall returnsl tol restingl levels?l Potassiuml channels

Answer:l

Sodiuml channelsl willl de-inactivate,l returningl tol thel closedl position

Potassiuml channelsl willl alsol close,l butl theyl remainl openl longl enoughl tol causel al hyperpolarizingl undershootl asl potassiuml continuesl tol movel towardl itsl equilibriuml potentiall ofl -80l mV.

QUESTION

Oncel thel voltage-gatedl channelsl close,l whatl twol itemsl reestablishl thel properl ionicl concentrationsl neededl forl electrochemicall gradients?

Answer:l

1.l Sodium-potassiuml pumps 2.l Leakl channels

QUESTION

Whatl determinesl maximuml firingl ratel ofl al cell?

Answer:l

Thel statusl ofl ionl channelsl inl neuronall membrane

QUESTION

Whatl isl periodl inl whichl al secondl actionl potentiall cannotl bel firedl underl anyl circumstances

Answer:l 2 / 3

Absolutel refractoryl period

QUESTION

Duringl thel undershoot,l whilel thel neuronl isl hyperpolarized,l al larger-than-normall stimulusl isl neededl tol makel thel celll reachl thresholdl again.l Actionl potentialsl canl bel fired,l butl al strongerl stimulusl isl neededl thanl whenl thel celll isl atl rest.l Thisl describesl whatl period?

Answer:l

Relativel refractoryl period

QUESTION

Whenl doesl thel absolutel refractoryl periodl occur?l Relative?

Answer:l

Absolutel -l Occursl rightl afterl depolarizationl |l Relativel -l occursl duringl repolarization

QUESTION

Statusl ofl sodiuml andl potassiuml gatesl duringl eachl stagel ofl AP

Answer:l

Atl rest:l bothl Nal andl Kl channelsl arel closed

Depolarization:l Nal =l openl completely,l shortl livedl |l Kl =l startingl tol slowlyl open

Repolarization:l Nal =l inactivatedl andl closedl |l Kl =l completelyl openl

Hyperpolarization:l Nal =l onlyl closed,l notl inactivatedl |l Kl =l inactivated

QUESTION

Actionl potentialsl onlyl movel inl onel direction,l froml thel celll bodyl tol thel presynapticl terminal.l Describel thel pathwayl (3)

Answer:l

1.l Axonl hillock 2.l Axon 3.l Presynapticl terminal

QUESTION

• / 3