USMLE

Cardiac Impulse

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Cardiovascular
  1. Cardiovascular Overview
  2. CO2 Transport
  3. Heart
  4. Cardiac Impulse
  5. Blood Pressure
  6. Arteries and Arterioles
  7. Veins and Venules
  8. Capillaries
  9. Circulation
  10. Blood
  11. Hemoglobin
  12. Blood Clotting
  • Topic Anchor: Cardiac Impulse
    • Process
      • Sinoatrial (SA) node
        • Initiates action potentials and sets rhythm of the heart (pacemaker)
      • Atrioventricular (AV) node
        • Conducts electrical impulses from atria to ventricles (hence, “atrio-ventricular”)
      • Bundle of His
        • Carries electrical impulses from AV node to bundle branches between both ventricles
      • Purkinje fibers 
        • Conductive fibers in ventricular walls
        • Allow for strong, unified contraction of ventricles 
    • Contractions spread to surrounding cardiac muscle via intercalated discs
      • Cell connections with desmosomes and gap junctions
        • Gap junctions allow rapid transfer of electrical impulses