The composition of circulation system systemic circulation(体循环) left ventricle _ the aorta organs right atrium 左心室主动脉一全身器官右心房 pulmonary circulation （肺循环) right ventricle→ gas exchange in the lung pulmonary artery left atrium 右心室 肺动脉 肺内气体交换 左心房The composition of circulation system systemic circulation (体循环) left ventricle the aorta organs right atrium 左心室 主动脉 全身器官 右心房 pulmonary circulation ( 肺循环) right ventricle pulmonary artery gas exchange in the lung left atrium 右心室 肺动脉 肺内气体交换 左心房