What are the 3 stages of the cardiac cycle?

• 1. Atrial systole:

  • Ventricles are relaxed
  • Atria fills with blood from veins
  • Atria contracts
  • Atria pressure is greater than ventricule pressure
  • AV valves open
  • Blood forced into ventricles
• 2. Ventricular systole:

  • Atria relax
  • Ventricle contracts
  • Ventricle pressure is greater than atria pressure
  • AV valves close
  • Ventricle pressure is greater than aorta pressure
  • SL valves open
  • Blood is forced into the arteries
• 3. Diastole:

  • Atria and ventricles relax
  • Aorta pressure is greater than ventricle pressure
  • SL valves close
  • Blood returns to atria from high pressure in arteries
  • Atria fill again
  • Atria pressure is greater than ventricle pressure
  • AV valves open
  • Blood flows passively into ventricles