This lecture covers the properties of cardiac fibers, the generation of the electrical signal for cardiac pumping, the electromechanical coupling in cardiac muscle, and the cardiac cycle during systole and diastole. It also explains the source of the cardiac rhythm at three levels and provides an example of a normal ECG trace. The lecture further discusses the structure and function comparison of skeletal, cardiac, and smooth muscle, the distribution of blood in the circulatory system, and the mechanisms of cardiac contraction and blood circulation in the body.