Conduction system

Question 1

What is the definition of conduction system?

Answer 1

a set of structures in the cardiac muscle which create and transmit an electrical impulse, forcing the atria and ventricles to contract.

Question 2

Name the five structures which pass the electrical impulse through the cardiac muscle in a co-ordinated fashion.

Answer 2

1. SA node
2. AV node
3. Bundle of His
4. Bundle braches
5. Purkinjie fibres

Question 3

What does the SA node do?

Answer 3

Generates an electrical impulse and fires it through the atria walls, causing them to contract. It is also known as the ‘pacemaker’ as the firing rate will determine heart rate.

Question 4

What does the AV node do?

Answer 4

Collects the impulse and delays it for 0.1 seconds to allow the atria to finish contracting. It then sends the impulse to the Bundle of His.

Question 5

What does the Bundle of His do?

Answer 5

It splits the impulse into two, ready to separate into each ventricle.

Question 6

What do the bundle branches do?

Answer 6

They carry the impulse to the base of the ventricle.

Question 7

What do the purkinjie fibres do?

Answer 7

They distribute the impulse through the ventricle walls, causing them to contract.

Question 8

How does the conduction finish?

Answer 8

Once the electrical impulses’ journey is complete, the atria and ventricles relax and the heart re-fills with blood.