Compléter Heart control and pulmonary circulationVersion en ligne Fill the blanks activity on pulmonary circulation and cardiac cycle par Idafe Perez Jimenez 1 1 . Blood enters the right carried by the vena and the left atrium carried by the pulmonary . 2 . The node sends an electric signal that makes the atria contract , but the signal is held back at the node so the ventricles' contraction gets delayed . This allows blood to enter the ventricles . 3 . After a delay of approximately 0 . 1 , the signal is passed on to the of , which branches out to the fibres and makes the ventricles contract . 4 . The valve prevents blood from flowing back to the right atrium , and the valve prevents blood from flowing back to the left atrium . Blood is pumped from the right ventricle , through the valve onto the and from there to the body ; and through the valve onto the artery and from there to the .