Cardiac action potentials

Question 1

What is depolarisation?

Answer 1

The process by which muscle fibres are stimulated to contract

Question 2

What is repolarisation?

Answer 2

The process by which muscle fibres relax

Question 3

What is the refractory period?

Answer 3

Myocardial cells can’t respond to any electrical stimulus from the condition system unless it has been fully repolarised
So the period from which the depolarised cells are then repolarising is called the refractory period

Question 4

Name the 3 ‘pacemakers’ within the heart.

Answer 4

SA node
AV node
Purkinji fibres

Question 5

What is the rate of the SA node?

Answer 5

60 to 100 bpm

Question 6

What is the rate of the AV node?

Answer 6

40 to 60 bpm

Question 7

What is the rate of the Purkinji fibres?

Answer 7

20 to 40 bpm

Question 8

What happens if the SA node fails?

Answer 8

The AV node takes over the initiation of electrical conduction in the heart.
Therefore becoming the ‘pacemaker’