The left ventricle of the heart receives the deoxygenated blood from the left atrium which it pushes the deoxygenated blood to the pulmunary semi-lunar valve to the pulmonary trunks to the veins back to the lungs so that the carbon dioxide contained in the blood can be exhaled while the right ventricle pushes the oxygenated blood from the right atrium to the aorta, passing through the aortic pulmonary valve.
It is a coordinated function in anatomy and physiology, since the left ventricle receives the deoxygenated blood its function is to deliver it to the lungs to exhaled or the host can't survive, same with the latter.