Answer:
Oxygen-rich blood flows from the lungs back into the left atrium (LA), or the left upper chamber of the heart, through four pulmonary veins. Oxygen-rich blood then flows through the mitral valve (MV) into the left ventricle (LV), or the left lower chamber.
OR
The blood becomes oxygenated in the lungs. Oxygenated blood leaves the lung via the pulmonary vein. Blood moves into the left ventricle. Blood is pumped into the aorta, which carries oxygenated blood around the body.
I dont understand what you mean but importance wise the picture would be most impotant