#cardiac_muscle__cardiacmuscle__heart_muscle__heartmuscle  the muscle tissue of the heart; adapted to continued rhythmic contraction
  supertype:  muscular_tissue__muscle  animal tissue consisting predominantly of contractile cells
  part of:  heart.internal_organ
  subtype:  cardiac_pacemaker__cardiacpacemaker__pacemaker__sinoatrial_node__SA_node  a specialized bit of heart tissue that controls the heartbeat
  subtype:  papillary_muscle__papillarymuscle  any of several muscles associated with the atrioventricular valves; "the papillary muscles contract during systole to prevent regurgitation of blood into the atria"
  subtype:  atrioventricular_bundle__bundle_of_His__atrioventricular_trunk__truncus_atrioventricularis  a bundle of modified heart muscle that transmits the cardiac impulse from the atrioventricular node to the ventricles causing them to contract
  subtype:  atrioventricular_node  a node of specialized heart muscle located in the septal wall of the right atrium; receives impulses from the sinoatrial node and transmits them to atrioventricular bundle
  subtype:  myocardium  the middle muscular layer of the heart wall
  subtype:  Purkinje_fiber  a specialized cardiac muscle fiber that is part of the Purkinje network
  subtype:  Purkinje_network__Purkinje's_tissue__Purkinje's_system  a network of Purkinje fibers that carry the cardiac impulse from the atrioventricular node to the ventricles of the heart and causes them to contract

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