This is heard loudest in the aortic valve and pulmonary valve area.

这个声音可以在主动脉瓣和肺动脉瓣听诊区被清晰地听到。

But, unlike the tricuspid valve, the pulmonary valve doesn't have any of those chordae tendineae.

但与三尖瓣不同，肺动脉瓣没有腱索。

Now after both the aortic and pulmonary valves have shut down, the atrioventricular valves open again, letting the cycle start all over again.

当主动脉瓣和肺动脉瓣都关上后，房室瓣再次打开，使心动周期重新开始。

Then, if you place a stethoscope in the left second intercostal space, at the left upper sternal border, you can hear the pulmonary valve closing.

然后，你将听诊器放到左第二肋间隙，在左胸骨上缘，你将听到肺动脉瓣关闭的声音。

So during inspiration, the closing of the pulmonary valve is heard slightly later than the aortic valve, and that's called the physiologic splitting of the S2.

所以在吸气时，肺动脉的关闭声，略晚于主动脉的关闭声，这被称作S2的生理性分裂。

S1, caused by the atrioventricular valves closing, at the beginning of systole, and S2, caused by the aortic and pulmonary valves closing, at the beginning of diastole.

S1是由于房室瓣的关闭导致的，发生在收缩早期；S2是由于主动脉瓣和肺动脉瓣的关闭导致的，发生在舒张早期。

Once it's passed the pulmonary valve, the blood goes into the pulmonary arteries, which carry blood away from the heart to the left and right lung.

一旦血液通过肺动脉瓣，便会进入肺动脉；肺动脉将血液从心脏输送到左肺和右肺。

That being said, that contraction pumps the blood out the pulmonary valve, which just like the tricuspid valve has three cusps and also prevents blood from going backward.

也就是说，心脏收缩将血液泵出肺动脉瓣；与三尖瓣一样，肺动脉瓣也有三个尖瓣，也可防止血液倒流。

It takes a little bit longer for the right ventricle to squeeze the extra blood into the pulmonary arteries and it takes a little bit longer for the pulmonary valve to close.

这使右心室需要更长的时间将多余的血挤入肺动脉；同时，肺动脉关闭的时间变长。

The second heart sound " dub" , or S2, originates from the closing of the aortic and pulmonary valves, right after the ventricles have ejected the blood.

第二心音“dub”， 即S2，是心室射血之后由于主动脉瓣和肺动脉瓣关闭产生的。