Autorhythmic pacemaker cells and phases of action potential is briefly discussed in this video. Important concepts related with each step are discussed. There is brief introduction electric conduction system of heart. Timeline 0:00 Introduction 0:20 Action potential within cardiac muscle cells (graphical representation) 0:51 Depolarization 1:10 Plateau phase 1:42 Repolarization 2:25 Absolute refractory period 3:00 Comparison between skeletal and cardiac action potential 4:17 Pacemakers of heart 5:26 Electrical conduction system of heart 6:50 Pacemaker activity