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Echocardiography > Innervation > Flashcards

Flashcards in Innervation Deck (63):
1

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

endocardium outwards

2

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

epicardium inwards

3

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

apex to base

4

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

base to apex

5

Which part of the nervous system controls the HR?

autonomic

6

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

sympathetic

7

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

parasympathetic

8

conduction path immediately following the AV node

Bundle of His

9

conduction path immediately following the SA node

interatrial tract/Bachmann's bundle

10

conduction path immediately following the Bundle of His

R and L bundle branches

11

conduction path immediately following either bundle branch

Purkinje fibres

12

excitation coupling

process of an electrical stimulus causing a mechanical event

13

name and number the phases of an action potential

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

14

phase 3 of an action potential

plateau

15

phase 2 of an action potential

early repolarization

16

phase 4 of an action potential

resting state

17

phase 0 of an action potential

depolarization

18

phase 1 of an action potential

repolarization

19

time for one action potential to complete

200 ms

20

change in voltage inside a cardiac cell during depolarization

-90 mV to +40-50 mV

21

events during depolarization: voltage and ions

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

22

depolarization: excitable or refractory?

refractory

23

early repolarization: excitable or refractory?

refractory

24

events of early repolarization

cardiac cell begins returning to a negative state

25

events during plateau

sarcomere contracts

26

plateau: excitable or refractory?

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

27

repolarization: excitable or refractory?

excitable, but by a strong stimulus only

28

resting state: excitable or refractory?

excitable

29

events during repolarization

cardiac cell returns to -90 mV state

30

events during resting state

polarity approaches ideal depolarization threshold

31

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

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

32

structures involved in intrinsic conduction

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

33

role of the SA node

primary pacemaker

34

heart rate, as stimulated by the SA node

60-100 bpm

35

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

SA node

36

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

interatrial tract/Bachmann's bundle

37

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

either of AV node or Bundle of His/AV bundle

38

primary pacemaker

SA node

39

secondary pacemaker

interatrial tract/Bachmann's bundle

40

3rd pacemaker

AV node

41

4th pacemaker

AV bundle/Bundle of His

42

Bundle of His, aka

AV bundle

43

AV bundle, aka

Bundle of His

44

role of AV node

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

45

role of Bundle of His

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

46

role of AV bundle

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

47

role of bundle branches

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

48

intrinsic conduction structure that accelerates impulse for efficient systolic contraction

right and left bundle branches

49

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

AV node

50

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

Bundle of His/AV bundle

51

segment of ECG associated with bundle branch stimulation

QRS complex

52

electrical event associated with the QRS complex of the ECG

bundle branch stimulation

53

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

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

54

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

wide QRS complex

55

role of Purkinje fibres

stimulate ventricular wall and pap muscle contraction

56

intrinsic conduction structure that stimulates depolarization of the pap muscles

Purkinje fibres

57

intrinsic conduction structure that stimulates depolarization of the ventricles

Purkinje fibres

58

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

Purkinje fibres

59

5th pacemaker

Purkinje fibres

60

Why does the RV contract slightly before the LV?

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

role of Vagus nerve

stimulates the SA & AV nodes via extrinsic conduction

62

factors affecting the sympathetic nervous system, and causing increased HR

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

63

effect of sympathetic nervous system on cardiac output

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