 Dear students, in this topic, we shall discuss the excitatory and conductive system of the heart. The heart has a specialized system for generating rhythmic electrical impulses. It also has a system to conduct these impulses to all parts of the heart rapidly. These impulses cause and control the rhythmic contraction of all chambers of the heart. Dear students, the rhythmicity of these electric impulses generated by the heart cause the contraction of atria about one-sixth of a second ahead of ventricular contraction. This is the rhythm which is found in the framework of all cardiac chambers. Which chambers will be contracted before and after? So, the atria contracts approximately one-sixth of a second ahead of the ventricular contraction. This time lapse allows the filling of ventricles before they contract. This rhythmity of impulses also allows when ventricles contract, all the muscle fibers that are all parts of the ventricles also contract simultaneously. Dear students, the excitatory system of the heart comprises of the pacemaker region, which is also called the sinoatrial or SA note. This pacemaker region in which the rhythmical impulses are generated. Dear students, the components of conductive system of the heart include, number one, the atrial inter-nodal pathways, which conduct impulses from the sinoatrial, that is SA node, to the AV node. The third component is conductive system's AV node, which conducts impulses into the ventricles. This conductive system's third component is the AV bundle, which is called as ASB. It conducts impulses from atria into the ventricles. The fourth component of conductive system includes the left and right branches of atrioventricular bundle, or AV bundle. Incommonly, we also call bundle branches. Dear students, the fifth component of the conductive system of the heart comprises of the purkinje fibres. These purkinje fibres branch off from the bundle branches. They conduct impulses to all parts of the ventricles.