EKG book..basics of reading an EKG

Question 1

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

Answer 1

Negative

polarity maintained by membrane pumps

Question 2

This is the fundamental electrical event of the heart

*this happens spontaneously in pacemaker cells

Answer 2

DEPOLARIZATION

Question 3

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

Answer 3

DEPOLARIZATION

Question 4

All waves on an EKG are manifestations of _______ and _______

Answer 4

Depolarization and repolarization

Question 5

3 types of cells in heart

Answer 5

Pacemaker
Electrical conducting
Myocardial (contractile machinery)

Question 6

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

Answer 6

1. Electrical characteristics of cell

2. External neurohormonal input

Question 7

A pacemaker cell does NOT have a true..

Answer 7

Resting potential

Question 8

What is the dominant pacemaker of the heart?

Answer 8

Sinoatrial (SA) node

*located high up in RIGHT atrium

Question 9

What is the typical firing rate of SA node cells?

Answer 9

60-100

Question 10

Vagal stimulation does what to the SA node firing rate

Answer 10

Slows it down!

Question 11

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

Answer 11

Electrical conducting cells

Question 12

Conducting fibers at the top of the intra-atrial septum

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

Answer 12

Bachman’s bundle

Question 13

Largest part of the heart tissue!

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

Answer 13

Myocardial cells

Question 14

Myocardial cells contain lots of ______ and______

Answer 14

Actin and myosin

Question 15

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

Answer 15

Excitation-contraction Coupling

Question 16

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

Answer 16

SLOWLY!

Question 17

Duration
Amplitude
Configuration

Answer 17

3 characteristics of EKG waves

Question 18

Unit of measure for duration on EKG

Answer 18

fraction of a second

Question 19

Unit of measure for amplitude on EKG

Answer 19

milivolts (mV)

Question 20

Horizontal axis on an EKG measures…

Answer 20

Time! (in fraction of a second)

Question 21

Distance across 1 small square (horizontally) represents..

Answer 21

0.04 seconds

Question 22

Distance across 1 large square (horizontally) represents..

Answer 22

0.2 seconds (5x greater than a small square)

Question 23

The vertical axis on an EKG measures…

Answer 23

Voltage (in milivolts, mV)

Question 24

Distance of 1 small square vertically represents..

Answer 24

0.1 mV

Question 25

Distance of 1 large square vertically represents..

Answer 25

0.5 mV

Question 26

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

Answer 26

Atrial contraction!

Question 27

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

Answer 27

P wave

Question 28

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

Answer 28

P wave

Question 29

Because the SA node is in the R atrium...

Answer 29

The R atrium contracts before the L atrium

Question 30

The first part of the p wave represents ? | The second part of the p wave represents?

Answer 30

First part...R atrial depolarization | Second part..L atrial depolarization

Question 31

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

Answer 31

Interventricular septum (this slow it down)

Question 32

When does the electrical conduction slow down?

Answer 32

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

Question 33

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

Answer 33

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

Question 34

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

Answer 34

Autonomic nervous system

Question 35

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

Answer 35

The flat line right after the p wave

Question 36

Bundle of His R and L Bundle branches Terminal Purkinje fibers

Answer 36

ventricular conducting system

Question 37

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

Answer 37

Bundle of His

Question 38

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

Answer 38

R bundle branch

Question 39

Divides into: - septal fascicle - anterior fascicle - posterior fascicle

Answer 39

L bundle branch

Question 40

Termination of R and L bundle branches is..

Answer 40

Purkinje Fibers

Question 41

Purkinje fibers deliver electrical current into the...

Answer 41

Ventricular myocardium

Question 42

Ventricular myocardial depolarization causes..

Answer 42

Ventricular contraction

Question 43

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

Answer 43

ventricles have MUCH MORE MUSCLE MASS than the atria

Question 44

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

Answer 44

Intricacy

Question 45

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

Answer 45

Q wave

Question 46

The first upward deflection is a...

Answer 46

R wave

Question 47

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

Answer 47

R-prime

Question 48

The first downward deflection following an upward deflection...

Answer 48

S wave

Question 49

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

Answer 49

It is the first wave of a complex | any other downward wave is an S wave

Question 50

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

Answer 50

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

Question 51

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

Answer 51

Left ventricular activation | because L ventricle about 3x more muscle mass than R ventricle

Question 52

After myocardial cells depolarize, there is a brief..

Answer 52

refractory period (unable to be stimulated at this point)

Question 53

Ventricular REPOLARIZATION is represented by which wave?

Answer 53

T wave

Question 54

Ventricular repolarization is much ______ than ventricular depolarization

Answer 54

slower

Question 55

T wave is more _____ than the QRS complex

Answer 55

broad (bc ventricular repol is slower than ventricular depol)

Question 56

Segment

Answer 56

straight line

Question 57

Interval

Answer 57

at least 1 wave plus connecting straight line

Question 58

P wave plus straight line connecting to QRS complex

Answer 58

PR interval

Question 59

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

Answer 59

PR segment

Question 60

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

Answer 60

PR interval

Question 61

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

Answer 61

PR segment

Question 62

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

Answer 62

ST segment

Question 63

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

Answer 63

ST segment

Question 64

Includes QRS complex, ST segment and T wave

Answer 64

QT interval

Question 65

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

Answer 65

QT interval

Question 66

Describes duration of QRS complex alone, without any connecting segments

Answer 66

QRS interval

Question 67

Measures duration of ventricular depolarization

Answer 67

QRS interval