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Clin Med Cardio Exam 1 > Electrocardiography > Flashcards

Electrocardiography Flashcards

1
Q

What is the #1 cause of death for males and females?

A

Cardiovascular disease

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2
Q

How many times does your heart beat/day? How many times/year?

A

100,000 daily

35 million yearly

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3
Q

How much does your heart weigh?

A

9-12 oz

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4
Q

How much of the chest cavity does the heart take up?

A

2/3 of the left sternal border

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5
Q

What provides the heart with its blood supply, oxygen, and nutrients?

A

Coronary arteries

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6
Q

Where do the coronary arteries originate?

A

Base of ascending aorta immediately above cusps of aortic valve

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7
Q

Does the heart receive blood during systole or diastole?

A

Diastole

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8
Q

Where is the myocardium most venerable to external forces?

A

Immediately to the left of the sternum, anterior side

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9
Q

supplies the SA node and the AV node

A

Right coronary artery

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10
Q

What happens when someone has an issue with their right coronary artery?

A

They’re going to have major electrophys changes due to the SA node and the AV node not having a good supply of blood

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11
Q

What feeds the lateral wall of the heart?

A

Left coronary

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12
Q

What feeds the inferior wall of the heart?

A

Right coronary

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13
Q

What wall is most concerning

to have an MI?

A

Anterior wall – one major concern over time – may eventually develop aneurism

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14
Q

99% of cardiac cells are?

A

Myocyte cells

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15
Q

Why are myocyte cells striated?

A

So they can contract

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16
Q

What is the purpose of gap junctions (intercalated discs)

in myocyte cells?

A

So that the impulse can jump from cell to cell

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17
Q

Myocyte cells are ______ controlled

A

Involuntarily

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18
Q

What is the other 1% of cardiac cells?

A

Pacemaker cells

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19
Q

What does it mean that pacemaker cells are autorythmic?

A

They can generate an AP on their own

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20
Q

Pacemaker cells are coupled to myocyte cells via?

A

Gap junctions

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21
Q

What is the resting membrane potential of a Pacemaker cell??

A

There isn’t one

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22
Q

What are the 3 types of pacemaker cells?

A

SA cells
AV cells
Purkinje cells

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23
Q

What is the last type of cardiac cell?

A

Specialized conducting cells

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24
Q

What is the pathway of an impulse through the heart?

A

SA node, Interatrial pathway, internodal pathway, AV node,

bundle of his, right and left bundle branches, Purkinje fibers

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25
Q

Minimal change in polarity required to produce an action potential

A

Threshold

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26
Q

Change in electrical potential that occurs inside and outside the cell when stimulated

A

Action potential

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27
Q

The SA node and the AV node have a ______ response action potential

A

slow

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28
Q

How do the SA node and AV node keep from firing at the same time?

A

They have different resting potentials

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29
Q

The SA node has a _____ resting membrane potential than the AV node

A

Higher

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30
Q

What is phase 4 of the SA and AV node action potential?

A

Spontaneous depolarization (pacemaker potential) that triggers an AP once the threshold is met

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31
Q

What is the threshold of the SA and AV node?

A

between -40 and -30 mV

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32
Q

What is phase 0 of the SA and AV node action potential?

A

Depolarization phase

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33
Q

What is phase 3 of the SA and AV node action potential?

A

Replarization

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34
Q

When does a pacemaker cell completely depolarize?

A

-60mV

35
Q

SA/AV: At -60mV (phase 4), what is influxing into the cell?

A

Na+

36
Q

SA/AV: At -50mV (phase 4), what is influxing into the cell

A

Ca++

37
Q

SA/AV: At phase 0 (depolarization), what is influxing into the cell?

A

Ca++

38
Q

SA/AV: At phase 3 (repolarization), what is happening in the cell?

A

Outward flux of K+ and inactivated channels of Ca++

39
Q

What is required for pacemaker channels to become activated?

A

A hyper polarized state

40
Q

What is happening in phase 4 of the Purkinje fiber AP?

A

Slow Na+ leaked inward at -90mV (resting membrane potential)

41
Q

What is happening at phase 0 of purkinje fiber action potential?

A

Fast Na+ entry (depolarization)

42
Q

What is happening at phase 1 of purkinje fiber action potential?

A

Na+ channels inactivated

43
Q

What is happening at phase 2 of purkinje fiber action potential?

A

Slow Ca++ entry and K+ exit

44
Q

What is happening at phase 3 of purkinje fiber action potential?

A

Repolarization - Fast K+ exit

45
Q

Pacemaker cells have ____ which means they don’t need a neighboring cell to tell them to fire

A

Automaticity

46
Q

Once a pacemaker cell reaches -60mV, what happens?

A

The cycle spontaneously happens again, which is why pacemaker cells are said to have “no resting membrane potential”

47
Q

Can myocyte cells be autorhytymic?

A

NO!

48
Q

Myocyte cells have a ____ response and a _____ resting membrane potential

A

Fast

True

49
Q

Is there more sodium on the outside of the cell or the inside?

A

Outside

50
Q

Is there more K+ on the outside of a cell or the inside?

A

Inside

51
Q

What is the resting membrane potential of a myocyte? What Phase is RMP?

A

-90mV

Phase 4

52
Q

What is the threshold for depolarization of a myocycte? What phase is depolarization?

A

-70mV

Phase 0

53
Q

What phase is it in a myocyte cell when the Na+ channels close and K+ leaves the cell slowly?

A

Phase 1

54
Q

What phase is it in a myocyte cell when Ca2+ enters the cell slowly and K+ leaves the cell?

A

Phase 2

55
Q

What phase is it in a myocyte cell when K+ channels close and Na+ rapidly influxes?

A

Depolarization! Phase 0

56
Q

What phase is it when all channels are closed, but K+ is exiting the cell?

A

Phase 4, RMP

57
Q

What phase is it when the calcium channels close, and K+ leaves the cell rapidly?

A

Phase 3, repolarization

58
Q

No stimulus no matter how strong will depolarize the cell

A

Absolute refractory period

59
Q

A sufficiently strong simtulus will depolarize the myocardial cell

A

Relative refractory period

60
Q

How many times does the SA node cell depolarize per minute?

A

60 to 100

61
Q

How many times does the AV cell depolarize per minute?

A

40 to 60

62
Q

How many times does the purkinje cell depolarize per minute?

A

20-40

63
Q

Which side of the heart pumps more blood?

A

They both pump the same

64
Q

Does conduction velocity occur faster in the LBB or the RBB?

A

LBB

65
Q

What causes ventricular myocytes to depolarize?

A

Na+ entering the cell

66
Q

Which wall is opposite the inferior wall?

A

Lateral wall

67
Q

If the HR is 50bpm, which autorhythmic cell is likely the pacemaker of the heart?

A

AV node cell

68
Q

The primary ion responsible for depolarization of the AV node?

A

Ca2+

69
Q

How long does it take for specialized conduction to go from the SA node to the far side of the left atrium?

A

0.09 seconds

70
Q

How long does it take for specialized conduction to go from the SA node to the AV node?

A

0.03 seconds

71
Q

How long does it take for specialized conduction to go from the SA node to the bundle of his?

A

.16s

72
Q

How long does it take for specialized conduction to go from the SA node to the purkinje fibers?

A

.19s

73
Q

How long does it take for specialized conduction to go from the SA node to the epicardial wall?

A

.22s (1/5 of a second)

74
Q

Sympathetic innervation of the heart is accomplished by the hormones __?

A

Epinephrine and norepinephrine

75
Q

What types of receptors do epinephrine and norepinephrine bind to?

A

Adrenergic

76
Q

When the sympathetic system acts on the heart, heart rate, conduction velocity, and force of contraction all ??

A

Increase

77
Q

Parasymphathetic innervation of the heart is accomplished by the hormone

A

acetylcholine

78
Q

acetylcholine binds to what type of receptors?

A

muscarinic

79
Q

When he parasympathetic system acts on the heart, the heart rate and conduction velocity ?

A

Decrease

80
Q

The inside of myocardial cells is more _____ charged in relationship to the outside where it is more ____ charged

A 
Inside = negative
Outside = positive
81
Q

A wave of depolarization or repolarization travels from cell to cell via ___ ___

A

Gap junctions

82
Q

Whenever there is a difference in charge inside or outside the cell, a ___ is formed

A

Vector

83
Q

When a vector is formed, this creates a _____

A

Wave (ECG)

84
Q

What is the flow of electricity through the heart?

A 
SA node
Atria
AV node
Bundle of his
Purkinje fibers
Ventricles

Clin Med Cardio Exam 1 (3 decks)

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