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EMRG 1230- CARDIAC UNIT > Electrophysiology of the Heart > Flashcards

Electrophysiology of the Heart Flashcards

1
Q

The electrical conduction system main function?

A

creates electrical impulse and transmit to the rest of the myocardium

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2
Q

What do the internodal pathways do?

A

Transmit the impulse from the SV node to the AV node

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3
Q

What is the final component in the conduction system?

A

Purkinje system, innervates myocardial cells

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4
Q

What is the heart’s natural pacemaker?

A

SA node

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5
Q

What does the SA node do?

A

Controls the beat based on the information it receive from the nervous circulatory and endocrine systems

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6
Q

What does the pacemaker create?

A

an organized beating of all cardiac cells in specialized sequence

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7
Q

The lower the HEART RATE the ____ heart block…

A

BIGGER

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8
Q

PACEMAKER SETTINGS:
SA NODE
AV NODE
Bundle of HIS
BRANCHES
PURKINJE SYSTEM

A

60-80 BPM
40-60 BPM
40-45 BPM
40-46 BPM
20-40 BPM

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9
Q

Where is the SA node found?

A

upper part of the right atrium at it’s junction with the superior vena cava

electrical impulses are generated here

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10
Q

What is the main purpose of the internodal pathways?

A

transmit the pacing impulse from the SA node to the AV node

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11
Q

Where are the internodal pathways found?

A

in the walls of the right atrium and inter- atrial

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12
Q

What are the 3 internodal pathways?

A

Anterior, middle and posterior

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13
Q

What is the bachmann bundle?

A

small tract of the specialized cells that transmit impulses through the inter-atrial septum

it is the path for electrical activity for the left atrium

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14
Q

What is the function of the AV node?

A

slows down the conduction from the atria to the ventricles long enough for the atrial contraction, then allows the signal to pass into the ventricles

helps maintain output of the heart at the max level

controls the HR (electrical relay station)

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15
Q

What artery supplies the AV node?

A

right coronary artery

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16
Q

Where does the bundle of His start?

A

AV node

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17
Q

What is the function of the bundle of His?

A

transmits impulses from the AV node to the purkinje fibres then to the ventricles

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18
Q

What is the only route of communication between the atria and the ventricles??

A

Bundle of His

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19
Q

Where does the Left Bundle Branch begin?

A

the end of the bundle of His

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20
Q

Where does the Left Bundle Branch end?

A

the start of the left anterior (LAF) and left posterior fascicles (LPF)

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21
Q

Where does the Right Bundle Branch start and finishes?

A

at the bundle of His and terminates in the purkinje fibres

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22
Q

What is the purkinje system?

A

Made up of individual cells just beneath endocardium

carry contraction impulses from the left and right bundle branches to the ventricles

directly innervates myocardial cells

23
Q

What do they purkinje fibres initiate?

A

ventricular depolarization cycle

24
Q

In terms of electrophysiology, what does an electrical stimulus stimulate?

A

Muscle tissue contraction

25
Q

What are characteristics of pacemaker cells?

A

Automaticity
Excitability
Conductivity
Contractility

26
Q

Define: Automticity

A

generate their own electrical impulses

27
Q

Define: Excitability

A

Irritability (to certain drugs)
Availability to respond to a charge (why we can defilbrillate)

28
Q

Define: Conductivity

A

Pass a charge on the to next cell

29
Q

Define: Contractility

A

Ability to shorten and contract!

30
Q

What are the phases of normal electrical activity of the heart?

A

Polarization, relaxation
Depolarization, contraction
Re-polarization , getting ready to contract again

31
Q

What is polarization?

A

State of readiness
muscle is relaxed and ready to receive electrical impulses

32
Q

Where is K, Na & Ca in a polarized state?

A

Potassium= inside
Sodium= outside
Calcium= outside
Polarized= equal ( + and - charge) on both sides

33
Q

Where is K, Na & Ca during a depolarized state?

A

Sodium= comes into the cell
Potassium= moves OUT of the cell
and Calcium moves IN and stays longer to maintain contraction

34
Q

Why does CALCIUM stay longer during the depolarization phase?

A

To maintain contraction

35
Q

Where is K, Na & Ca during a re-polarized state?

A

Potassium goes BACK INTO the cell
Sodium= MOVES OUT of the cell
Calcium= leaves the cell too

36
Q

What is phase 4?

A

Polarized resting membrane potential
K = IN

37
Q

What is phase 0?

A

Depolarization
Na = IN

38
Q

What is phase 1?

A

Early depolarization
K= OUT

39
Q

What is phase 2?

A

Plateau phase
Ca = IN to help maintain contraction
K= OUT

40
Q

What is phase 3?

A

Rapid repolarization
K= OUT

41
Q

What is the refractory period?

A

Brief period during which cells will resist stimulation

Lasts approx. 0.5ms after the membrane reaches the threshold potential

42
Q

Absolute refractory period is…

A

When they will NOT RESPOND to any stimulus no matter HOW strong!

43
Q

Relative refractory period is…

A

a FEW milliseconds after the absolute when the membrane is repolarizing and restoring the membrane potential

during this time, the membrane will ONLY Respond to VERY strong stimuli

44
Q

What is the conduction pathway of the electrical signals of the heart?

A

SA node
Internodal and interatrial pathways
AV node
Bundle of His
Right and left bundle branches
Perkinje’s fibers
Ventricular muscle

45
Q

What is step one in electrical activity?

A

SA node activity and atrial activation begins

46
Q

What is step two in electrical activity?

A

Stimulus reaches the AV node

47
Q

What is step three in electrical activity?

A

Delay at the AV node, 100msec
Atrial contraction begins

48
Q

What is step four in electrical activity?

A

Impulses travels along the septum wall within the AV bundle and branches to the perkinje fibers

49
Q

What is step five in electrical activity?

A

Impulse is distributed and relayed through ventricular myocardium

atrial contraction compete

ventricular contraction starts

50
Q

ECG Representation: What does atrial depolarization look like?

A

the P wave on the ECG

51
Q

ECG Representation: What does ventricular depolarization look like?

A

the QRS complex, action potential here is moving from the AV node through the bundle of His and into the purkinje fibers

52
Q

ECG Representation: What does ventricular repolarization look like?

A

the T wave, ventricles relax during this phase

53
Q

ECG Representation: What does repolarization of purkinje fibers look like?

A

U wave, not always visible, very very small

EMRG 1230- CARDIAC UNIT (11 decks)

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