Examl 2:l BIOl 202/l BIO202l (NEWl 2025/l
2026l Update)l Humanl Anatomyl andl
Physiologyl IIl Review|l Questionsl &l
Answers|l Gradel A|l 100%l Correctl
(Verifiedl Solutions)-l GCU
QUESTION
Listl severall waysl thatl al ventricularl heartl celll andl pacemakerl heartl celll differl inl termsl
ofl actionl potentiall generation.
Answer:
Ventricularl myocyte:
-l Restingl potentiall =l -90mV
-l Stimulusl froml neighboringl cardiocytel (notl autonomic)
-l Threshold:l -75mV
-l Plateaul broughtl onl byl calcium
-l Fastl depolarization
-l K+l causesl repolarization
Pacemakerl cell:
-l Restingl potential:l -60mVl tol -70mV
-l Funnyl currentl causesl depolarizationl (spontaneousl andl automatic)
-l Threshold:l -40mVl tol -50mV
-l Nol plateau
-l Slowl depolarization
-l K+l causesl repolarization
QUESTION
Describel thel importancel ofl thel plaeteaul inl al heartl cell'sl actionl potential.l Whatl ionl isl
responsiblel forl thisl plateau?
Answer:
,Thel plateaul allowsl forl al sustainedl contractionl (Ca2+)
QUESTION
Listl ANDl describel thel keyl differencesl betweenl al skeletall musclel APl andl al heartl
musclel celll AP.
Answer:
1.l All-or-nonel lawl =l Gapl junctionsl inl intercalatedl discsl allowl cardiacl musclel cellsl tol
bel linked,l sol activationl ofl al smalll groupl ofl cellsl spreadsl likel al wavel throughl thel
heart.l Thel heartl hasl "synchronistic"l contractionl asl opposedl tol skeletall muscle.
2.l Automacityl (authorhythmicity)l =l Somel cardiacl musclel cellsl arel "self-excitable"l
allowingl forl rhythmicl wavesl ofl contractionl tol adjacentl cellsl thoughoutl thel heart.l
Skeletall musclel cellsl mustl bel stimulatedl byl independentl motorl neuronsl asl partl ofl al
motorl unit
3.l Lengthl ofl absolutel refractoryl periodl =l Thisl periodl ofl cardiacl musclel cellsl isl muchl
largerl (250msec)l thanl skeletall musclel cellsl (vsl 2-3msec),l preventingl wavel summation/l
tetanicl contractionsl whichl wouldl causel thel heartl tol stopl pumping
QUESTION
Whatl isl anl ECG/EKG?
Answer:
Itl tellsl youl ifl there'sl electricall activityl inl thel heart,l howl strongl itl is,l andl thel relativel
directionl ofl thel activity
QUESTION
Outline/Drawl thel sequencel ofl eventsl whichl anl ECGl (EKG)l shows,l makingl surel tol
includel thel following:
a.l Pl wavel
b.l P-Rl intervall
c.l QRSl complexl
,d.l Q-Tl intervall
e.l Tl wavel
f.l Makel surel tol relatel whichl regionsl ofl thel ECKl correlatel tol thel regionsl ofl thel heartl
thatl arel depolarizing.
Answer:
A.l Atrial Depolarizel (Pl wave)
B.l froml startl ofl atriall depolarizationl (P-Rl interval)
C.l ventriclesl depolarizel (QRSl complex)
D.l froml ventricularl depolarizationl tol ventricularl repolarizationl (Q-Tl interval)
E.l -l ventriclesl repolarizel (Tl wave)
QUESTION
Whatl isl anl ectopicl focusl ofl pacemakerl tissue?l Howl canl thisl bel problematic?
Answer:
Regionl ofl spontaneousl firingl (notl SA).l Thisl couldl interruptl thel SAl node'sl signall whichl
couldl screwl upl thel pumpingl actionl orl leadl tol anl arrhythmia.
QUESTION
Whatl doesl thel P-Rl intervall allowl tol happenl duringl thel contractionl ofl thel heart?
Answer:
Itl allowsl forl al delayl atl thel AVl nodel tol allowl thel atrial tol completelyl emptyl beforel thel
ventriclesl contract
QUESTION
Whatl happensl ifl thel P-Rl intervall isl tool long?l Inl otherl words,l wherel isl thel wavel ofl
depolarizationl gettingl bottlel necked?
Answer:
, Therel isl al conductionl failurel atl thel AVl nodel (calledl heartl block).l Thisl couldl causel thel
ventriclesl notl tol receivel thel signall tol depolarize.
QUESTION
Wherel doesl ANPl andl BNPl comel from?l Whatl causesl theirl release?l Whatl arel theirl
effectsl onl thel cardiovascularl systeml whenl theyl arel released?
Answer:
ANPl andl BNPl comel froml thel heart.l Increasedl bloodl pressurel causesl theirl release.l
Theyl blockl aldosteronel andl decreasel thel bloodl pressure
QUESTION
Whatl isl atriall fibrillation?l Whyl mightl someonel havel tol bel onl bloodl thinnersl ifl theyl
havel thisl condition?
Answer:
isl al quiveringl orl irregularl heartbeatl (arrhythmia)l thatl canl leadl tol bloodl clots,l stroke,l
heartl failurel andl otherl heart-relatedl complications.l
Bloodl thinnersl reducel thel riskl ofl strokes
QUESTION
Whatl doesl natriuresisl mean?
Answer:
Excretionl ofl sodiuml vial urinel inl kidneys
QUESTION
Whatl isl al PVC?l Canl thisl bel al normall occurrence?
2026l Update)l Humanl Anatomyl andl
Physiologyl IIl Review|l Questionsl &l
Answers|l Gradel A|l 100%l Correctl
(Verifiedl Solutions)-l GCU
QUESTION
Listl severall waysl thatl al ventricularl heartl celll andl pacemakerl heartl celll differl inl termsl
ofl actionl potentiall generation.
Answer:
Ventricularl myocyte:
-l Restingl potentiall =l -90mV
-l Stimulusl froml neighboringl cardiocytel (notl autonomic)
-l Threshold:l -75mV
-l Plateaul broughtl onl byl calcium
-l Fastl depolarization
-l K+l causesl repolarization
Pacemakerl cell:
-l Restingl potential:l -60mVl tol -70mV
-l Funnyl currentl causesl depolarizationl (spontaneousl andl automatic)
-l Threshold:l -40mVl tol -50mV
-l Nol plateau
-l Slowl depolarization
-l K+l causesl repolarization
QUESTION
Describel thel importancel ofl thel plaeteaul inl al heartl cell'sl actionl potential.l Whatl ionl isl
responsiblel forl thisl plateau?
Answer:
,Thel plateaul allowsl forl al sustainedl contractionl (Ca2+)
QUESTION
Listl ANDl describel thel keyl differencesl betweenl al skeletall musclel APl andl al heartl
musclel celll AP.
Answer:
1.l All-or-nonel lawl =l Gapl junctionsl inl intercalatedl discsl allowl cardiacl musclel cellsl tol
bel linked,l sol activationl ofl al smalll groupl ofl cellsl spreadsl likel al wavel throughl thel
heart.l Thel heartl hasl "synchronistic"l contractionl asl opposedl tol skeletall muscle.
2.l Automacityl (authorhythmicity)l =l Somel cardiacl musclel cellsl arel "self-excitable"l
allowingl forl rhythmicl wavesl ofl contractionl tol adjacentl cellsl thoughoutl thel heart.l
Skeletall musclel cellsl mustl bel stimulatedl byl independentl motorl neuronsl asl partl ofl al
motorl unit
3.l Lengthl ofl absolutel refractoryl periodl =l Thisl periodl ofl cardiacl musclel cellsl isl muchl
largerl (250msec)l thanl skeletall musclel cellsl (vsl 2-3msec),l preventingl wavel summation/l
tetanicl contractionsl whichl wouldl causel thel heartl tol stopl pumping
QUESTION
Whatl isl anl ECG/EKG?
Answer:
Itl tellsl youl ifl there'sl electricall activityl inl thel heart,l howl strongl itl is,l andl thel relativel
directionl ofl thel activity
QUESTION
Outline/Drawl thel sequencel ofl eventsl whichl anl ECGl (EKG)l shows,l makingl surel tol
includel thel following:
a.l Pl wavel
b.l P-Rl intervall
c.l QRSl complexl
,d.l Q-Tl intervall
e.l Tl wavel
f.l Makel surel tol relatel whichl regionsl ofl thel ECKl correlatel tol thel regionsl ofl thel heartl
thatl arel depolarizing.
Answer:
A.l Atrial Depolarizel (Pl wave)
B.l froml startl ofl atriall depolarizationl (P-Rl interval)
C.l ventriclesl depolarizel (QRSl complex)
D.l froml ventricularl depolarizationl tol ventricularl repolarizationl (Q-Tl interval)
E.l -l ventriclesl repolarizel (Tl wave)
QUESTION
Whatl isl anl ectopicl focusl ofl pacemakerl tissue?l Howl canl thisl bel problematic?
Answer:
Regionl ofl spontaneousl firingl (notl SA).l Thisl couldl interruptl thel SAl node'sl signall whichl
couldl screwl upl thel pumpingl actionl orl leadl tol anl arrhythmia.
QUESTION
Whatl doesl thel P-Rl intervall allowl tol happenl duringl thel contractionl ofl thel heart?
Answer:
Itl allowsl forl al delayl atl thel AVl nodel tol allowl thel atrial tol completelyl emptyl beforel thel
ventriclesl contract
QUESTION
Whatl happensl ifl thel P-Rl intervall isl tool long?l Inl otherl words,l wherel isl thel wavel ofl
depolarizationl gettingl bottlel necked?
Answer:
, Therel isl al conductionl failurel atl thel AVl nodel (calledl heartl block).l Thisl couldl causel thel
ventriclesl notl tol receivel thel signall tol depolarize.
QUESTION
Wherel doesl ANPl andl BNPl comel from?l Whatl causesl theirl release?l Whatl arel theirl
effectsl onl thel cardiovascularl systeml whenl theyl arel released?
Answer:
ANPl andl BNPl comel froml thel heart.l Increasedl bloodl pressurel causesl theirl release.l
Theyl blockl aldosteronel andl decreasel thel bloodl pressure
QUESTION
Whatl isl atriall fibrillation?l Whyl mightl someonel havel tol bel onl bloodl thinnersl ifl theyl
havel thisl condition?
Answer:
isl al quiveringl orl irregularl heartbeatl (arrhythmia)l thatl canl leadl tol bloodl clots,l stroke,l
heartl failurel andl otherl heart-relatedl complications.l
Bloodl thinnersl reducel thel riskl ofl strokes
QUESTION
Whatl doesl natriuresisl mean?
Answer:
Excretionl ofl sodiuml vial urinel inl kidneys
QUESTION
Whatl isl al PVC?l Canl thisl bel al normall occurrence?
