I'm gonna start with the left atrium.

我将要从左心房开始。

Now, sometimes, individuals might have an atrial septal defect, a small opening between the right and left atrium.

同时，某些人患有房间隔缺损的，即右心房与左心房之间有一个小的缺口。

It then propagates out through both atria, including bachmann's bundle in the left atrium, and contracts both atria.

然后它传导到两个心房，包括通过Bachmann氏束到达左心房，并且导致两个心房的收缩。

It can go up into the left atrium.

它可以进入左心房。

After entering the left atrium, the blood goes through the second atrioventricular valve called the mitral valve into the left ventricle.

进入左心房后，血液穿过第二个房室瓣膜，称为二尖瓣，进入左心室。

Finally, Marfan syndrome is a risk factor for mitral valve prolapse, where the mitral valve pouches into the left atrium during systole.

最后，马方综合征也是二尖瓣脱垂的一个危险因素，即二尖瓣在收缩期时突向左心房。

These pulmonary veins deliver the oxygenated blood to the left atrium.

这些肺静脉将含氧血液输送到左心房。

This is the valve that separates the left atrium and the left ventricle.

这是分隔左心房和左心室的瓣膜。

The oxygen-rich blood moves into a venule and then, eventually, into a pulmonary vein that dumps the blood into the left atrium.

富含氧气的血液汇入小静脉，最终进入肺静脉；肺静脉将血液排入左心房。

Pulmonary blood vessels shrink pumping more blood through the pulmonary veins into the left atrium.

肺血管收缩，将更多的血液通过肺静脉泵入左心房。