The venae cavae empties the deoxygenated blood into the right atrium of the heart.

腔静脉将脱氧血注入心脏的右心房。

So this trip from the left ventricle of the heart, to the body, and back to the right atrium of the heart is called the systemic circulation.

血液从左心室到身体，再回到心脏的右心房的行程，被称为体循环。

This trip from the right ventricle of the heart, through the pulmonary artery to the lungs, and back to the left atrium of the heart is called the pulmonary circulation.

血液从心脏右心室，经过肺动脉到肺，再由肺静脉回到心脏左心房的行程，被称为肺循环。

The venae cavae has two divisions: the superior vena cava and the inferior vena cava, and these divisions both return blood to the right atrium of the heart.

上腔静脉和下腔静脉，这些分支都将血液回流到心脏的右心房。

In other words, it drains deoxygenated blood from the legs, back, abdomen and pelvis, and then it transports them all the way up to the right atrium of the heart.

换句话说，它从腿部、背部、腹部和骨盆排出脱氧血，然后将它们一直输送到心脏的右心房。

Now that blood is freshly oxygenated from its trip to the lungs, it returns to the left atrium of the heart and passively flows through the bicuspid (or mitral valve).

现在，血液从进入肺部时被新鲜氧化，回到心脏的左心房，并被动地流过二尖瓣（或mitral valve）。