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Cardiopulmonary > Electrical activity of the heart > Flashcards

Electrical activity of the heart Flashcards

1
Q

The path of an electrical impulse from the SA node to the left atrium is facilitated by:

A

Bachmanns bundle

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2
Q

What are the 4 characteristics nodal tissue in the heart?

A

Excitability
Automaticity
Conductivity
Contractility

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3
Q

What is excitability?

A

The ability of cells to respond to electrical chemical or mechanical stimulation

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4
Q

What is automaticity?

A

The unique ability of cardiac muscle to initiate a spontaneous electrical impulse

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4
Q

What is conductivity?

A

The ability of the myocardial tissue to spread or radiate electrical impulses

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5
Q

What is contractility?

A

The ability of a cardiac cell to contract

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6
Q

What is the period of time during which the myocardium cannot be stimulated?

A

Refractory period

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7
Q

What is the intrinsic rate of contraction set by the SA node?

A

60-100 bpm

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8
Q

What is the intrinsic rate of contraction set by the AV node?

A

40-60 bpm

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9
Q

Myocytes at rest are referred to as _______

A

Polarized

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10
Q

When myocytes are at rest they have a ______ charge

A

Negative

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11
Q

What is the role of sodium in the electrical activity of the heart?

A

cause atrial and ventricular depolarization and contraction

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12
Q

What is the role of calcium in the electrical activity of the heart?

A

maintains/slows impulse movement through the AV node to allow for ventricular filling
Follows sodium in to cell

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13
Q

What is the role of potassium in the electrical activity of the heart?

A

Repolarization of myocytes

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14
Q

What happens to the net charge of a cell when it is depolarized

A

Becomes positively charged

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15
Q

Depolarization of the myocardial cells cause the cells to _______

A

Contract

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16
Q

What is another term for repolarization?

A

Recovery phase

17
Q

What ion initially enters the cell, making it positive and causing depolarization?

A

Sodium

18
Q

Describe ion movement during depolarization and then repolarization

A

Sodium moves into the cell, starting depolarization. Calcium follows and strengthens and prolongs depolarization. The entry of sodium and potassium push potassium out of the cell initially, however during repolarization potassium reenters the cell pushing sodium and calcium out of the cell

19
Q

What is the intrinsic rate set by ectopic foci?

A

20-40 bpm

20
Q

What portion of the nervous system can alter the rhythmic intrinsic contraction of the heart?

A

Autonomic nervous system

21
Q

What is the autonomic nervous system composed of?

A

The sympathetic nervous system
The parasympathetic nervous system

22
Q

What does the sympathetic nervous system do to the heart?

A

Speed up heart rate
Increase the strength of the contraction

23
Q

What does the parasympathetic nervous system do to the heart?

A

Slow down heart rate
Decrease strength of contractility

24
Q

What does the P wave on an EKG represent?

A

Atrial contraction/atrial depolarization

25
Q

What does the QRS complex represent on an EKG?

A

Ventricular contraction/ventricular depolarization

26
Q

What does the T wave represent on an EKG?

A

Ventricular repolarization

27
Q

What does the isoelectric line represent?

A

Polarization
Resting state

28
Q

What does the Q wave represent on an EKG?

A

The arrival of the electrical impulse at the bundle of His

29
Q

What does the R wave represent on an EKG?

A

Contraction of the left ventricle

30
Q

What does the S wave represent on an EKG?

A

Contraction of the right ventricle

31
Q

What are the 2 phases of ventricular repolarization?

A

Plateau phase
Rapid phase

32
Q

Where does the absolute refractory period start?

A

The beginning of QRS complex

33
Q

Where does the absolute refractory period end?

A

The middle of the T wave

34
Q

Where does the relative refractory period begin?

A

The beginning of the down slope of the T wave

35
Q

Where does the supernormal refractory period begin?

A

The end of the T wave

36
Q

T/F: A strong electrical stimulus cannot cause a depolarization of myocardial tissue during the relative and supernormal refractory period

A

False. A strong electrical stimulus can cause a depolarization of myocardial tissue during the relative and supernormal refractory period

37
Q

The rapid phase of ventricular repolarization is represented by the:

A

The T wave

38
Q

Ventricular repolarization is represented on an EKG by

A

The ST segment and the T wave

39
Q

On an electrocardiogram, the end of the PR segment close to the apex of the T wave represents

A

The absolute refractory period

Cardiopulmonary (6 decks)

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