How does the heart help the lungs do its job in the human body?

The heart is the bodies blood pump. Blood with a low oxygen level enters the heart at the right atria where it is pumped to the right ventricle and then out of the heart through the pulmonary artery ( the only artery in the body that contains low oxygenated blood) and to the lungs. While in the lungs, the blood enters the alveoli where it off loads carbon dioxide molecules and up loads oxygen molecules. The now oxygenated blood returns to the heart into the left atria, is pumped to the left ventricle and then out to the body through the Aorta where it supplies the oxygen to the bodies cells and collects carbon dioxide and other wastes. The cycle begins again.