Cardiac Cycle

1. Right & left ventricle relax, the right & left atria contract causing the bicuspid & tricuspid valves to open. This causes blood to flow into the ventricles.

2. Both atria then relax, & the two ventricles contract to push the blood out of the heart & into the pulmonary artery & aorta. This happens because the semi-lunar valves open, while the biscupid & tricuspid valves shut as the ventricle pressure…