I. Deoxygenated blood enters the Vena Cava into the right Atrium.
II. The right Atrium contracts and pumps the blood from Tricuspid Valve to the right Ventricle.
IV. The right Ventricle pumps the blood to the pulmonary vein to the lungs.
V. The exchange of gas takes place from the alveoli.
VI. Oxygenated blood flows back through the pulmonary vein to the left Atrium.
VII. The left Atrium contracts and pumps the blood from Mitral Valve to the Left Ventricle.
VIII. The oxygenated blood flows out the heart through the arteries.
The cycle repeats.