1. Cardiac Cycle is INITIATED by the SAN
2. SAN sends a WAVE OF DEPOLARISATION to the AV
3. The AV DELAYS the wave of depolarisation to give the atria time to contract.
4. Wave of depolarisation rapidly goes down the Bundle of His and Purkinye fibers to the apex
5. The wave is spread across the ventricular walls AWAY from the apex which results in a strong UNIFIED contraction.