INTRINSIC CONDUCTION SYSTEM

• 2 systems regulate heart activity:

  • Autonomic nervous system (ANS)
  • Intrinsic conduction system or nodal system
• Intrinsic conduction system - sets the heart rhythm; ensures heart muscle depolarization in one direction; enforces a heart rate of 75 bpm
• Atrial cells have 60 bpm

  Ventricular cells have 20-40 bpm
• Components of the nodal system:

  • Sinoatrial (SA) node - located in the right atrium; heart's pacemaker
  • Atrioventricular (AV) node - located at the junction of the atria and ventricles
  • Atrioventricular (AV) bundle (bundle of His) - located at the interventricular septum
  • Purkinje fibers - spread within the ventricle wall muscles
• Tachycardia - rapid heart rate, over 100 bpm

  Bradycardia - slow heart rate, less than 60 bpm