Pressure Changes in Cardiac Cycle

• Graph


  • Depicts blood pressure changes in the left side of the heart during the cardiac cycle
• Top graph


  Illustrates pressure changes
• Bottom graph


  Shows the volume of the left ventricle
• Green line


  Pressure in the left atrium
• Red line


  Pressure in the left ventricle
• Orange line


  Aortic pressure
• Atrial systole (atrium contraction)


  1. Pressure in the left atrium increases

  2. Atrioventricular valve opens

  3. Blood flows into the left ventricle

  4. Pressure in the left ventricle increases
• Ventricular systole (left ventricle contracts)

  Left ventricular pressure significantly increases
• When left ventricular pressure exceeds atrial pressure

  Atrioventricular valve closes
• When left ventricular pressure surpasses aortic pressure

  1. Aortic semilunar valve opens

  2. Blood ejected into the aorta
• Ventricular diastole (left ventricle relaxes)


  Left ventricular pressure falls
• When left ventricular pressure drops below aortic pressure

  1. Aortic semilunar valve closes

  2. Blood cannot re-enter the ventricle
• While the left ventricle contracts and relaxes

  Left atrium refills with blood
• When left ventricular pressure falls below left atrial pressure

  1. Atrioventricular valve reopens

  2. Cycle repeats
• Blue line (volume graph)

  • Blood volume increases as it enters the left ventricle during atrial contraction
  • Decreases when the ventricle contracts and ejects blood into the aorta
  • Increases again as the ventricle relaxes and refills
• Understanding these pressure and volume changes during the cardiac cycle is crucial for comprehending heart function and blood circulation
• Cardiac cycle pressure graph