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# Electrical System of the Heart The purpose of the electrical system of the heart: 1. Coordinate the pumping of the four heart chambers 2. Control the heart rate so that the heart speeds up and slows down as the demands of the body change. ## Intrinsic conduction system (nodal system) Heart muscle...

# Electrical System of the Heart The purpose of the electrical system of the heart: 1. Coordinate the pumping of the four heart chambers 2. Control the heart rate so that the heart speeds up and slows down as the demands of the body change. ## Intrinsic conduction system (nodal system) Heart muscle cells contract, without nerve impulses, in a regular, continuous way with the aid of the pacemaker cells. ### Characteristics of Pacemaker Cells: - Smaller than contractile cells - Don’t contain many myofibrils - No organized sarcomere structure - Do not contribute to the contractile force of the heart # The Heart Conduction System ## Pacemakers: 1. Sinoatrial node (SA) 2. Atrioventricular node (AV) 3. Atrioventricular bundle 4. Bundle branches 5. Purkinje fibers