During joint diastole, both atria and ventricles are in a relaxed state. During this phase, the right auricle receives deoxygenated blood from superior and inferior vena cava and left auricle receives oxygenated by the pulmonary vein. The valves ( both tricuspid and bicuspid valves) between auricle and ventricle remain open and blood flows freely from auricle to ventricle while semilunar valves are closed.

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