Electrical Activity of the heart OBJECTIVES Explain the types of cardiac action potentials. Define the ionic basis of cardiac action potentials. Explain the temporal changes in cardiac excita bility 心肌细胞的快反应动作电位和慢反应动作电位; 心肌细胞的电生理特性(传导性和兴奋性)Electrical Activity of the Heart OBJECTIVES • Explain the types of cardiac action potentials. • Define the ionic basis of cardiac action potentials. • Explain the temporal changes in cardiac excitability. • 心肌细胞的快反应动作电位和慢反应动作电位； • 心肌细胞的电生理特性（传导性和兴奋性）