Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Physiology II > Lecture 3 -ECG > Flashcards

Lecture 3 -ECG Flashcards

1
Q

What are all cells in the heart?

A

Both contractile and able to produce their own action potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Pacemaker cells

A

Cells of the sinoatrial node Produce lots of AP (~60-100/min) Very little contraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Myocytes

A

Strongly contracting cells of heart walls, especially the ventricles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Action potential Initiated at SA node where does it first spread to?

A

Throughout both atria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What happens in AV node?

A

Action potential can spread from atria to ventricles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What does ventricular conduction system consist of?

A

Bundle of His Purkinje fibres

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the ECG?

A

Graphic record of direction and magnitude of electrical activity generated by depolarisation and repolarization of atria and ventricles of heart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is membrane potential?

A

The voltage change across the membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the 3 distinct wave forms of ECG?

A

P wave. QRS complex T wave

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

When does the P wave occur?

A

When the wave of depolarisation spreads across the atria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Why is the P wave smaller than QRS complex?

A

Atria have a smaller muscle mass than Ventricles and generate less electrical activity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

When does the ECG remain at base line?

A

When no net current flow is occurring in heart muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

P wave

A

Atrial Depolarisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

PR segment

A

AV nodal delay

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

QRS complex

A

Ventricular depolarisation (Atria repolarising simultaneously)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

ST segment

A

Time during which ventricles are contracting and emptying

17
Q

T wave

A

Ventricular repolarization

18
Q

TP segment

A

Time during which ventricles are relaxing and filling

19
Q

What is “Blocks”?

A

Areas of abnormal (or absent) conduction

20
Q

What is Reentries?

A

Areas where the conduction turn back on itself

21
Q

What is the effect of sympathetic stimulation on heart?

A

Controls heart action in emergency or exercise situations Require greater blood flow - “revs up” heart Speed up depolarisation so that threshold is reached more rapidly The rate of depolarisation increase due to greater inward movement of Na+ and Ca2+ though If and T type ca2+ channel More frequent action potential - increase heart rate Speed up the spread of AP throughout the specialised conduction pathway Increase contractile strength so that the heart beat more forcefully and squeeze out more blood Improve it’s effectiveness as a pump by increasing HR Decreasing delay between atrial and ventricular contraction Decreasing conduction time throughout heart - increase force of contraction Speeding up relaxation process so that more time is available for filling

22
Q

What is the effect of parasympathetic stimulation of heart?

A

ACH suppresses sympathetic activist by inhibiting the release of norepinephrine from neighbouring sympathetic nerve endings Increase potassium permeability of the pacemaker cells in SA node ( the rate at which AP are initiated is reduced) Decreases the AV nodes excitability (prolongs the transmission of impulses to the ventricles) Atrial contraction is weakened Has little effect on ventricular contraction

23
Q

Sympathetic stimulation

A

Various efferent fibres

24
Q

Parasympathetic stimulation

A

Vague nerve that affect SA node and AV node

25
Q

Atrial fibrillation

A

The ventricles won’t fill properly

26
Q

Ventricular tachycardia

A

Ventricles going faster than they can be refilled

27
Q

Ventricular fibrillation

A

Defibrillator required

28
Q

Second degree AV block

A

Can miss whole beats

AV node signals lost

29
Q

First degree AV block

A

Longer PR interval

Held in AV node

30
Q

Premature ventricular complex

A

Direction of the ECG wave is dependent on the direction of depolarisation wave
The ventricles are still contracting

31
Q

Third degree AV block

A

AV node no longer transmitting
Ventricles independently contracting
Stimulated by their own myogenic contraction or purkinje fibre

Physiology II (16 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions