Normally, oxygen-poor (blue) blood returns to the right atrium from the body, travels to the right ventricle, then is pumped through the pulmonary artery into the lungs where it receives oxygen.

• 正常情况下，贫氧血（蓝色）从全身回到右心房，进入右心室，然后被泵出经过肺动脉进入肺，在这里接受氧气。