YOUR AMAZING ELECTRICAL HEART

3 FINAL BURST OF POWER THAT SENDS BLOOD OUT TO THE BODY

THE current passes down into a bundle of cardiac muscle fibres (seen here in blue), then spreads rapidly through the muscles of the right and left ventricles, causing them to contract at the same time.

The whole process takes a break for about 0.5 seconds before it starts again, with the sinus node. This is how the normal resting heart rate is created.

Although pacemaker cells generate the electrical impulse that makes the heart beat, there are other nerves in the heart which can change the speed of the heart if required.

This can happen, for example, during periods of brisk exercise.