Please explain abut diastole and systole.

Asked by chetan24d | 22nd May, 2010, 05:07: PM

Expert Answer:


The Heartbeat

The heartbeat is made up of systole and diastole, which are the two stages of a heartbeat                            Systole: Stage when the ventricles of heart are contracting resulting in blood being pumped out to the lungs and the rest of the body.Diastole: Stage when the ventricles of the heart are relaxed and not contracting. During this stage, the atria are filled with blood and pump blood into the ventricles.

  • Thick, muscular walls of both ventricles contract.
  • Pressure rises in both ventricles, causing the bicuspid and tricuspid valves to close. Therefore, blood is forced up the aorta and the pulmonary artery.
  • The atria relax during this time. The left atrium receives blood from the pulmonary vein, and the right atrium from the vena cava.


  • Thick, muscular walls of both ventricles relax.
  • Pressure in both ventricles falls low enough for bicuspid valves to open.
  • The atria contract, and blood is forced into the ventricles, expanding them.
  • The blood pressure in the aorta is decreased, therefore the semi-lunar valves close.








Answered by  | 22nd May, 2010, 06:27: PM

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