OMG,is starts from the left ventricle, fresh blood from the left ventricle through body artery is pressed out, after the whole body organization and the organization to complete the exchange of oxygen and carbon dioxide throughout arterial blood into the venous blood, through back to the right atrium, inferior vena cava and then into the right atrium and the pulmonary artery into the lungs through the circulation, the venous blood into the artery, again by pulmonary vein into the left atrium, and finally into the left ventricle. After the blood from the right ventricle injection via the pulmonary artery flow to pulmonary capillaries, the gas exchange with alveolar air, absorb the oxygen and carbon dioxide, venous blood into the arterial blood; And then it flows back through the pulmonary vein to the left atrium