ANATOMY 1 Lecture Notes - Lecture 17: Purkinje Fibers, Heart Valve, Sinoatrial Node
Document Summary
During development, ~ 1% of cardiac muscle fibers become autorhythmic cells. = cells that repeatedly + rhythmically generate action potentials. Even if heart is removed from body => heart transplants. Autorhythmic cells act as natural pacemakers set rhythm for entire heart. Route that delivers action potentials through heart muscle. Cardiac excitation begins in sinoatrial node action potential travels through intercalated discs to muscle fibers of both atria => atria contract at same time. Action potential conducted along atrial muscles (intermodal fibers) reach atrioventricular node @ av node, action potential slows => time for atria to empty blood into ventricles. Only site where action potentials can conduct from atria to ventricles. From av bundle action potential enters right and left bundle branches => transported to apex of heart. Purkinje fibers @ apex relay action potential to contractile cells of the ventricular myocardium wave of contraction moves upward from apex.
