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PHYSIOLOGY > ELEMENTS OF CARDIAC FUNCTION > Flashcards

ELEMENTS OF CARDIAC FUNCTION Flashcards

1
Q

the other type of action potential, the slow response occurs in the ___________ which is the natural pacemaker region of the heart

and in the ______________ which is the specialized tissue that conducts the cardiac impulse from the atria to the ventricles

A

SA NODE
AV NODE

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2
Q

the resting membrane potential (phase 4) of the fast response cells is considerably more ________ than that of the slow-response cells

A

negative

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3
Q

in slow response cardiac tissue the action potential is propagated more __________ and conduction is more likely to be ________ than fast response cells

A

slowly
blocked

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4
Q

the various phases of the cardiac action potential are associated with changed in cell membrane permeability mainly by ______, _____, and ______ ions

A

sodium
potassium
calcium

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5
Q

the resting cell membrane has a relatively high permeability for ______

A

potassium

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6
Q

the specific potassium channel through which potassium passes during phase 4 is a voltage-regulated channel that conducts the _______________

A

inward rectifying Potassium current

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7
Q

the dependence of Vm on conductance and the intracellular and extracellular concentrations of potassium, sodium and other ions are described by the ________

A

chord conductance equation

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8
Q

FAST RESPONSE ACTION POTENTIALS
(Genesis of the Upstroke Phase 0)

when the resting membrane potential suddenly depolarized from ________ mV to the threshold level of approximately ____mV the cell membrane properties change dramatically

A

-90 mv
-65 mv

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9
Q

FAST RESPONSE ACTION POTENTIALS
(Genesis of the Upstroke Phase 0)

sodium enters myocyte through specific __________ that exist in the membrane

A

voltage activated sodium channels

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10
Q

FAST RESPONSE ACTION POTENTIALS
(Genesis of the Upstroke Phase 0)

the sodium channels open rapidly or ________ thereby resulting in an abrupt increase in sodium conductance. however once open the sodium channels _______ and sodium conductance rapidly decreases

A

activate
inactivate

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11
Q

FAST RESPONSE ACTION POTENTIALS
(Genesis of the Upstroke Phase 0)

with repolarization the channels transition to the ____ state from which it can then be reopened by another depolarization of Vm to the threshold

A

closed

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12
Q

FAST RESPONSE ACTION POTENTIALS
(Genesis of the Upstroke Phase 0)

when the sodium channels are inactivated they cannot be reopened and another action cannot be generated. the cell is said to be in its ___________

A

effective refractory period

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13
Q

FAST RESPONSE ACTION POTENTIALS
(Genesis of the Upstroke Phase 0)

during this period called the _________ another action potential can be generated but it requires a larger than normal depolarization of Vm

A

relative refractory period

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14
Q

FAST RESPONSE ACTION POTENTIALS
(Genesis of Early repolarization Phase 1)

repolarization is brief because of activation of a _______carried by Potassium.

A

transient outward current

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15
Q

FAST RESPONSE ACTION POTENTIALS
(Genesis of Plateau Phase 2)

during the action potential plateau _____ enters myocardiial cells through calcium channels

A

calcium

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16
Q

FAST RESPONSE ACTION POTENTIALS
(Genesis of Plateau Phase 2)

two types of calcium channels

A

L-type T-type

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17
Q

FAST RESPONSE ACTION POTENTIALS
(Genesis of Plateau Phase 2)

L-type channels are blocked by ____________ such as amlodipine, verapamil and diltiazem

A

calcium channel antagonists

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18
Q

FAST RESPONSE ACTION POTENTIALS
(Genesis of Plateau Phase 2)

the parasympathetic neurotransmitter ___________ decreases calcium conductance

A

acetylcholine

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19
Q

FAST RESPONSE ACTION POTENTIALS
(Genesis of Plateau Phase 2)

the reduction of potassium conductance at both positive and low negative values of Vm is called _____________. __________ is a characteristic of several potassium currents

A

inward rectification

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20
Q

FAST RESPONSE ACTION POTENTIALS
(Final repolarization Phase 3)

the duration of the plateau is substantially ____ in atrial myocytes than in ventricular myocytes because the magnitide of outward potassium currents are greater in atrial myocytes than in ventricular myocytes

A

substantially less

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21
Q

FAST RESPONSE ACTION POTENTIALS
(restoration of ionic concentration Phase 4)

the steady inward leak of sodium that enters the cell rapidly during the phase 0 and more slowly throughout the cardiac cycle would gradually depolarize the resting membrane voltage were it not for the ____________

A

Na+, K+ - ATPase

22
Q

certain cells in the heart notably those in the SA and AV nodes exhibit slow response action potentials, in these cells depolarization is achieved mainly by influx of_________ through L-type calcium channels instead of influx of _______ through fast sodium channels

A

calcium
sodium

23
Q

two types of potassium channels

A

delayed rectifier potassium currents
transient outward potassium current

24
Q

property of cardiac tissue is the ability to intiate its own beat

A

automaticity

25
Q

property of cardiac tissue

A

regularity of pacemaking activity

26
Q

_____________ blocks fast sodium current has no influence on the SA nodal action potential because the action potential upstroke is not produced by an inward sodium current through fast channels

A

tetrodoxin

27
Q

tetrodoxin blocks ____________has no influence on the SA nodal action potential because the action potential upstroke is not produced by an inward sodium current through fast channels

A

fast sodium current

28
Q

in the pacemaker cells of the SA node at least 3 ionic currents mediate slow diastolic depolarization

clue
outward
inward
inward

A

outward potassium current
hyperpolarization induced inward current
inward calcium current

29
Q

the hyperpolarization induced by _______ released from vagus nerve endings in the heart is achieved by the activation of specific potassium channels

A

acetylcholine

30
Q

the automaticity of pacemaker cells diminishges after these cells have been excited at a high frequency

A

overdrive suppression

31
Q

overdrive suppression results from the activity of membrane _____

A

sodoum potassium ATPase

32
Q

action potential duration in atrial myocytes is ______ than in ventricular myocytes because efflux of ______ is greater during the plateau in atrial myocytes than in ventricular myocytes

A

briefer
potassium

33
Q

abnormal prolongation of the AV conduction time is called _________

A

1st degree AV block

34
Q

the conduction pattern in which only a fraction of the atrial impulses are conducted to the ventricles

A

2nd degree AV block

35
Q

conduction pattern in which none of the atrial impulses reaches the ventricles is called a ___________ or complete AV block

A

3rd degree AV block

36
Q

triggered activity is caused by _____________ of two types

clue:
early
d

A

afterpolarization
early afterpolarization
delayed afterpolarization

37
Q

early afterdepolarizations are more likely to occuire when the heart rate is __________, while delayed afterdepolarizations more likely to occur when heart rate is ________

A

slow
high

38
Q

delayed afterpolarizations are associated with elevated intracellular _______

A

calcium

39
Q

during the ST interval the entire myocardium is _________

A

depolarized

40
Q

when firing of the SA node is decreased the heart rate also decreases

A

bradycardia

41
Q

increased SA node firing results in elevation of the heart rate

A

tachycardia

42
Q

if this premature depolarization occurs at regular interval or at an integral multiple of that interval the distance is called _________`

A

parasystole

43
Q

_____________ tachycardias originate from ectopic focus typically begin and end abruptly

A

ectopic tachycardias

44
Q

__________ inhibits the calcium atpase of the sarcoplasmic reticulum

A

phospholamban

45
Q

contraction of cardiac muscle is influenced by both ______ and ________

A

preload and afterload

46
Q

___________ is the force that stretches the relaxed muscle fibers, thereby increasing their resting length

A

preload

47
Q

________ is the force added to the muscle against which the contracting muscle must act

A

afterload

48
Q

in the venous pulse curve recorded from the jugular vein, 3 waves are apparent

A

a wave
c wave
v wave

49
Q

wave that occurs in pressure caused by atrial contraction

A

a wave

50
Q

wave that is caused by impact of the common carotid artery with the adjacent jugular vein and to some extent by the abrupt closure of the tricuspid valve in early ventricular systole

A

c wave

51
Q

reflects the rise in pressure associated with atrial filling

A

v wave

52
Q
A

PHYSIOLOGY (33 decks)

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