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Clin Med-Cardio pt 1 > EKG book..basics of reading an EKG > Flashcards

EKG book..basics of reading an EKG Flashcards

1
Q

What is the charge of the inside of a cardiac cell at rest?

A

Negative

polarity maintained by membrane pumps

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2
Q

This is the fundamental electrical event of the heart

*this happens spontaneously in pacemaker cells

A

DEPOLARIZATION

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3
Q

In non pacemaker cells, this occurs by the arrival of an electrical impulse that causes positively charged ions to cross the membrane..this continues until the whole heart is in this state

A

DEPOLARIZATION

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4
Q

All waves on an EKG are manifestations of _______ and _______

A

Depolarization and repolarization

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5
Q

3 types of cells in heart

A

Pacemaker
Electrical conducting
Myocardial (contractile machinery)

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6
Q

The rate of depolarization in pacemaker cells is determined by _________ and _________

A
  1. Electrical characteristics of cell

2. External neurohormonal input

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7
Q

A pacemaker cell does NOT have a true..

A

Resting potential

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8
Q

What is the dominant pacemaker of the heart?

A

Sinoatrial (SA) node

*located high up in RIGHT atrium

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9
Q

What is the typical firing rate of SA node cells?

A

60-100

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10
Q

Vagal stimulation does what to the SA node firing rate

A

Slows it down!

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11
Q

Long, thin cells that carry current rapidly to distant regions of heart

A

Electrical conducting cells

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12
Q

Conducting fibers at the top of the intra-atrial septum

  • allows for rapid activation of the L atrium from the R atrium
A

Bachman’s bundle

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13
Q

Largest part of the heart tissue!

Responsible for the heavy labor or repeatedly contracting and relaxing, thereby delivering blood to the body

A

Myocardial cells

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14
Q

Myocardial cells contain lots of ______ and______

A

Actin and myosin

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15
Q

When a wave of depolarization reaches a myocardial cell, calcium is released in the cell, causing the cell to contract

A

Excitation-contraction Coupling

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16
Q

A wave of depolarization, upon reaching myocardial cells, will spread HOW across the entire myocardium?

A

SLOWLY!

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17
Q

Duration
Amplitude
Configuration

A

3 characteristics of EKG waves

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18
Q

Unit of measure for duration on EKG

A

fraction of a second

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19
Q

Unit of measure for amplitude on EKG

A

milivolts (mV)

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20
Q

Horizontal axis on an EKG measures…

A

Time! (in fraction of a second)

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21
Q

Distance across 1 small square (horizontally) represents..

A

0.04 seconds

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22
Q

Distance across 1 large square (horizontally) represents..

A

0.2 seconds (5x greater than a small square)

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23
Q

The vertical axis on an EKG measures…

A

Voltage (in milivolts, mV)

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24
Q

Distance of 1 small square vertically represents..

A

0.1 mV

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25
Q

Distance of 1 large square vertically represents..

A

0.5 mV

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26
Q

SA cells spontaneously depolarize, wave of depolarization spreads outwards into atrial myocardium. Depolarization of atrial myocardial cells results in..

A

Atrial contraction!

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27
Q

During the atrial depolarization and contraction, electrodes record which wave?

A

P wave

28
Q

A recording of the spread of depolarization through atrial myocardium start to finish

A

P wave

29
Q

Because the SA node is in the R atrium…

A

The R atrium contracts before the L atrium

30
Q

The first part of the p wave represents ?

The second part of the p wave represents?

A

First part…R atrial depolarization

Second part..L atrial depolarization

31
Q

What must the electrical conduction be funneled through to get fro the atria to the ventricles?

A

Interventricular septum (this slow it down)

32
Q

When does the electrical conduction slow down?

A

When it reaches the AV node (for a fraction of a second)

33
Q

The conduction delay between the atria and ventricles allow for what?

A

The atria to finish contracting (and empty their blood volume) before the ventricles start

34
Q

Like the SA node, the AV node is also under what control?

A

Autonomic nervous system

35
Q

On an EKG, where is the delay of the AV node seen?

A

The flat line right after the p wave

36
Q

Bundle of His
R and L Bundle branches
Terminal Purkinje fibers

A

ventricular conducting system

37
Q

Emerges from AV node and almost immediately divides into R and L bundle branches

A

Bundle of His

38
Q

Brings current to the R side of inter ventricular septum all the way to apex of the R ventricle

A

R bundle branch

39
Q

Divides into:

  • septal fascicle
  • anterior fascicle
  • posterior fascicle
A

L bundle branch

40
Q

Termination of R and L bundle branches is..

A

Purkinje Fibers

41
Q

Purkinje fibers deliver electrical current into the…

A

Ventricular myocardium

42
Q

Ventricular myocardial depolarization causes..

A

Ventricular contraction

43
Q

The amplitude of the QRS complex is much greater than the p wave because the…

A

ventricles have MUCH MORE MUSCLE MASS than the atria

44
Q

The QRS complex is much more variable in shape than the P wave, reflecting greater ______ of the pathways of depolarization

A

Intricacy

45
Q

If the first deflection is downwards, it is a..

A

Q wave

46
Q

The first upward deflection is a…

A

R wave

47
Q

If there is a second upward deflection, it is a..

A

R-prime

48
Q

The first downward deflection following an upward deflection…

A

S wave

49
Q

A downward deflection can ONLY be a Q wave if..

A

It is the first wave of a complex

any other downward wave is an S wave

50
Q

The earliest part of the QRS complex represents depolarization of..

A

Interventricular septum (by septal fascicle of the L bundle branch)

51
Q

The R and L ventricles depolarize about the same time but what do we mostly see represented on the EKG?

A

Left ventricular activation

because L ventricle about 3x more muscle mass than R ventricle

52
Q

After myocardial cells depolarize, there is a brief..

A

refractory period (unable to be stimulated at this point)

53
Q

Ventricular REPOLARIZATION is represented by which wave?

A

T wave

54
Q

Ventricular repolarization is much ______ than ventricular depolarization

A

slower

55
Q

T wave is more _____ than the QRS complex

A

broad (bc ventricular repol is slower than ventricular depol)

56
Q

Segment

A

straight line

57
Q

Interval

A

at least 1 wave plus connecting straight line

58
Q

P wave plus straight line connecting to QRS complex

A

PR interval

59
Q

Straight line running from end of P wave to start of QRS complex

A

PR segment

60
Q

Measures the time from the start of atrial depolarization to the start of ventricular depolarization

A

PR interval

61
Q

Measures time from end of atrial depolarization to start of ventricular depolarization

A

PR segment

62
Q

Straight line connecting end of QRS complex to beginning of T wave

A

ST segment

63
Q

Measures time from end of ventricular depolarization to start of ventricular repolarization

A

ST segment

64
Q

Includes QRS complex, ST segment and T wave

A

QT interval

65
Q

Measures time from beginning of ventricular depolarization to end of ventricular repolarization

A

QT interval

66
Q

Describes duration of QRS complex alone, without any connecting segments

A

QRS interval

67
Q

Measures duration of ventricular depolarization

A

QRS interval

Clin Med-Cardio pt 1 (10 decks)

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