7 - ELECTRICAL ACTIVITY OF THE HEART

Question 1

1ST STEP (where does it start)

Answer 1

It starts in the Sino-atrial node (SAN), which is in the wall of the right atrium

Question 2

2nd STEP

Answer 2

waves of electrical activity are sent to the atrial walls, making the atria contract at the same time

Question 3

3rd STEP

Answer 3

A band of non-conducting collagen tissue prevents the waves of electrical activity from being passed directly from the atria to the ventricles

Question 4

4th STEP

Answer 4

Because of this, the waves of electrical activity are passed on from the SAN to the AVN (atrioventricular node)

Question 5

5th STEP

Answer 5

There is a slight delay before the AVN reacts to make sure the ventricles contract after the atria have emptied

Question 6

6th STEP

Answer 6

The AVN then sends the electrical activity to the bundle of His(muscle fibres responsible for conducting these waves)

Question 7

7th STEP

Answer 7

These waves of electrical activity are then sent to the finer muscle fibres in the right and left ventricle, called the Purkyne fibres

Question 8

8th STEP (final)

Answer 8

The purkyne fibres carry the waves of electrical activity to the muscular walls of the right and left ventricles, causing them to contract simultaneously