The heart conduction system

• What is the cardiac cycle ?

  The cardiac cycle is the sequence of events by which blood is pumped through the heart in one heart beat
• what are the two main phases of the cardiac cycle ?

  phase 1- diastole

  phase 2 - systole
• what is diastole ?

  this is where the heart is relaxed

  atrial diastole - atrial relax and fill with blood

  ventricular diastole -ventricular relax and fill with blood
• what is systole ?

  a period of contraction

  atrial systole -atria contract and eject blood into the ventricles

  ventricular systole- ventricles contract and eject blood out of the heart
• what is the SA node ?

  the hearts pacemaker

  for every electrical impulse it emits the heart beats
• what is the AV node ?

  it distributes the impulse to the lower chambers of the heart
• what is the bundle of his ?

  it splits the impulse to the left and right ventricle
• what are the purkinje fibres ?

  they surround the ventricles and spread the impulse from the bottoms causing ventricular systole
• What are the structures of the heart conduction system ?

  • SA node
  • AV node
  • Buncle of his
  • Purkinje fibres
• 1. atrial diastole
  2. ventricular diastole
  3. SA node sends an electrical impulse across the atria causing atrial systole
  4. the AV node receives the electrical impulse and distributes it to the bundle of his
  5. the bundle of his splits the impulse to the left and right ventricle
  6. the impulse spreads through the purkinje fibres from the bottom of the heart causing ventricular systole