Innervation Flashcards

1
Q

During ventricular depolarization, does the electrical stimulation occur from the endocardium outwards or the epicardium inwards?

A

endocardium outwards

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2
Q

During ventricular repolarization, does the electrical stimulation occur from the endocardium outwards or the epicardium inwards?

A

epicardium inwards

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3
Q

During ventricular depolarization, does the electrical stimulation occur from the base to the apex, or the apex to the base?

A

apex to base

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4
Q

During ventricular repolarization, does the electrical stimulation occur from the base to the apex, or the apex to the base?

A

base to apex

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5
Q

Which part of the nervous system controls the HR?

A

autonomic

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6
Q

Which part of the nervous system causes an increase in HR?

A

sympathetic

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7
Q

Which part of the nervous system causes a decrease in HR?

A

parasympathetic

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8
Q

conduction path immediately following the AV node

A

Bundle of His

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9
Q

conduction path immediately following the SA node

A

interatrial tract/Bachmann’s bundle

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10
Q

conduction path immediately following the Bundle of His

A

R and L bundle branches

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11
Q

conduction path immediately following either bundle branch

A

Purkinje fibres

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12
Q

excitation coupling

A

process of an electrical stimulus causing a mechanical event

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13
Q

name and number the phases of an action potential

A
0 - depolarization
1 - early repolarization
2 - plateau
3 - repolarization
4 - resting state
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14
Q

phase 3 of an action potential

A

plateau

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15
Q

phase 2 of an action potential

A

early repolarization

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16
Q

phase 4 of an action potential

A

resting state

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17
Q

phase 0 of an action potential

A

depolarization

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18
Q

phase 1 of an action potential

A

repolarization

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19
Q

time for one action potential to complete

A

200 ms

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20
Q

change in voltage inside a cardiac cell during depolarization

A

-90 mV to +40-50 mV

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21
Q

events during depolarization: voltage and ions

A

change in voltage inside a cardiac cell from -90 mV to +40-50 mV
influx of Na+ and Ca2+
efflux of K+

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22
Q

depolarization: excitable or refractory?

A

refractory

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23
Q

early repolarization: excitable or refractory?

A

refractory

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24
Q

events of early repolarization

A

cardiac cell begins returning to a negative state

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25
Q

events during plateau

A

sarcomere contracts

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26
Q

plateau: excitable or refractory?

A

refractory

only excitable by a VERY strong stimulus, and only towards the end of this phase/beginning of Phase 3

27
Q

repolarization: excitable or refractory?

A

excitable, but by a strong stimulus only

28
Q

resting state: excitable or refractory?

A

excitable

29
Q

events during repolarization

A

cardiac cell returns to -90 mV state

30
Q

events during resting state

A

polarity approaches ideal depolarization threshold

31
Q

What affect does the slope of Phase 4/resting state have on the action potential?

A

steeper slope: reaches threshold for depolarization faster = higher HR
flatter slope: reaches threshold for depolarization slower = slower HR

32
Q

structures involved in intrinsic conduction

A

SA node, atrial sarcomeres, AV node, Bundle of His/AV bundle, right and left bundle branches, Purkinje fibres

33
Q

role of the SA node

A

primary pacemaker

34
Q

heart rate, as stimulated by the SA node

A

60-100 bpm

35
Q

What structure in the intrinsic conduction stimulates a heart rate of 60-100 bpm?

A

SA node

36
Q

What structure in the intrinsic conduction stimulates a heart rate of 60-80 bpm?

A

interatrial tract/Bachmann’s bundle

37
Q

What structure in the intrinsic conduction stimulates a heart rate of 40-60 bpm?

A

either of AV node or Bundle of His/AV bundle

38
Q

primary pacemaker

A

SA node

39
Q

secondary pacemaker

A

interatrial tract/Bachmann’s bundle

40
Q

3rd pacemaker

A

AV node

41
Q

4th pacemaker

A

AV bundle/Bundle of His

42
Q

Bundle of His, aka

A

AV bundle

43
Q

AV bundle, aka

A

Bundle of His

44
Q

role of AV node

A

slows action potential from reaching the ventricular conduction system to allow the atria to fully contract first

45
Q

role of Bundle of His

A

stoplight: delays action potential from depolarizing ventricles to allow appropriate ventricular filling time

46
Q

role of AV bundle

A

stoplight: delays action potential from depolarizing ventricles to allow appropriate ventricular filling time

47
Q

role of bundle branches

A

accelerate impulse to prepare for efficient systolic contraction (QRS on ECG)

48
Q

intrinsic conduction structure that accelerates impulse for efficient systolic contraction

A

right and left bundle branches

49
Q

intrinsic conduction structure that slows action potential from reaching the ventricular conduction system to allow the atria to fully contract first

A

AV node

50
Q

intrinsic conduction structure that acts as a stoplight: delays action potential from depolarizing ventricles to allow appropriate ventricular filling time

A

Bundle of His/AV bundle

51
Q

segment of ECG associated with bundle branch stimulation

A

QRS complex

52
Q

electrical event associated with the QRS complex of the ECG

A

bundle branch stimulation

53
Q

What is indicated by a wide QRS complex, and why?

A

bundle branch block - impulse must travel along slower path to initiate contraction, through muscle instead of nerves

54
Q

What would you see on the ECG with a bundle branch block?

A

wide QRS complex

55
Q

role of Purkinje fibres

A

stimulate ventricular wall and pap muscle contraction

56
Q

intrinsic conduction structure that stimulates depolarization of the pap muscles

A

Purkinje fibres

57
Q

intrinsic conduction structure that stimulates depolarization of the ventricles

A

Purkinje fibres

58
Q

What structure in the intrinsic conduction stimulates a heart rate of 20-40 bpm?

A

Purkinje fibres

59
Q

5th pacemaker

A

Purkinje fibres

60
Q

Why does the RV contract slightly before the LV?

A

impulse short cuts across the moderator band within the RV apex, instead of all the way to the apex and up the outer walls, as in the LV

61
Q

role of Vagus nerve

A

stimulates the SA & AV nodes via extrinsic conduction

62
Q

factors affecting the sympathetic nervous system, and causing increased HR

A

Stress: fear, anger, excitement, fever, trauma, exercise

63
Q

effect of sympathetic nervous system on cardiac output

A

increases both the HR and the force of contraction (stroke volume)