Cardiac Cycle

• Cardiac diastole: all chambers are relaxed, and blood flows into the heart

  
• Atrial systole, ventricular diastole: atria contract, pushing blood into the ventricles

  
• Atrial diastole, ventricular systole: after atria relax, ventricles contract, pushing blood out of heart

  
• Physical activity makes the heart beat more quickly and more deeply, for an increased circulation of blood so that more oxygen and glucose can get to the muscles.