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Unformatted text preview: Cardiac Conduction The electrical activity of the heart is both myogenic and autorhythmic ; the electrical activity of the heart originates within the heart itself and is regular and spontaneous. Specialized cardiomyocytes called nodal cells are myogenic and autorhythmic and therefore enable the heart to beat regularly and spontaneously without input from the nervous system. Cardiac Nodes The sinoatrial node is the pacemaker of heart; it initiates the contraction of the heart and therefore sets the heart rate. The atrioventricular node is the electrical gateway to the ventricles. The bundle branches descend through the interventricular septum towards the apex and spread the depolarization through the walls of the ventricle. At the apex, Purkinje fibers spread upwards along the external walls of the ventricles. (See Figure 5). Figure 5 Electrical Activity of the Heart Sinoatrial Node Action Potential Unlike skeletal muscles (and most cardiomyocytes), nodal cells do not exhibit a stable resting...
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This note was uploaded on 01/30/2012 for the course BSC BSC1085 taught by Professor Sharonsimpson during the Fall '10 term at Broward College.
- Fall '10