cardiac cycle

• contraction- volume decreases, pressure increases

  relacation- volume increases, pressure decreases
• 1. atrial systole

  • wall of atria contract, volume decreases and pressure increases in atria
  • pressure higher in atria than ventricles forcing AV valves to open
  • blood forced into ventricles
  • ventricular diastole coincides with atricular systole
• 2. ventricular systole

  • wall of ventricles contract- volume decreases, pressure increases in ventricle
  • pressure higher in ventricles than atria
  • av valves close and sl valves open
  • ventricular systole coincides with atricular diatole(atria fill w blood again)
• diastole

  • ventricles and atria both relax
  • pressure in ventricles lower than atria so SL valves close
  • atria fill with blood via veins
  • pressure in atria higher than in ventricles causing AV valves to open and blood flows passively to ventricles