Blood is only expelled from the heart when it contracts.

收时，血液才从射出。

That is reassuring. But what about the other bad beats, the premature contractions in the heart's lower chambers?

这就让人放了。那其他有害跳，发生在下腔的期前收(室性期前收)呢?

The heart contracts and expands in a non-stop rhythm to push our blood around a system of arteries and veins.

不间断地收和舒张，推动血液在动脉和静脉系统流动。

Cotton was the heartbeat of the section, the planting and the picking were the diastole and systole of the red earth.

棉花便是本地区的脉搏，植棉和摘棉便是这红土的舒张和收。

Also, though, the timing of the PAC will also determine how the heart contracts and therefore what the ECG looks like.

此外，房性期前收的时机也决定了如何收以及因此产生的电图形状。

And this can quickly lead to cardiogenic shock, since the heart doesn't even have time to fill with blood before each contraction.

这很快会导致源性休克的发生，因在收之前还来不及充盈血液。

This is the term used to describe the contraction of the heart.

这是用来描述收的术语。

It would squeeze the capsule tightly as the heart contracted and still keep a firm grip on it when the heart was relaxed.

它可以随着的收轻微挤压胶囊，且在放松时，也能紧紧抓住。

On rare occasions, a sudden change in heart rhythm prevents the upper chambers of the heart from contracting normally.

在极少数情况下，节律的突然变化会妨碍上腔的正常收。

Alright, so also the location of the ectopic focus in the atria determines how the heart contracts and therefore what the ECG looks like.

并且房异位起搏点的位置决定了如何收以及因此产生的电图形状。

This is a term used to describe the contraction of the heart.

这是一个用来描述收的术语。

But they fire only at the time when the heart contracts, And they remain silent when the heart is relaxed.

但它们只在收时发出信号，而在放松时则保持沉默。

In other words, the contraction of the heart is shorter than the filling time.

换言之，收比充盈时间短。

The current stops the irregular contractions of the cardiac muscle, and gives the heart a chance to start beating normally.

电流停止了肌肉的剧烈收 ，并让有机会正常跳动。

Frank and Starling were looking at the amount of blood in the heart before the ventricles contract.

Frank 和Starling正在观察室收前的血流量。

Now in addition to systolic heart failure, you've also got diastolic heart failure, which is where the heart's squeezing hard enough but not filling quite enough.

除收性衰外，还有舒张性力衰竭，指的是收功能正常，但是在舒张期充盈受损。

If your heart has decreased contractility then it's going to have to work harder to maintain proper profusion of your body with blood.

如果收力下降，那么它将不得不更加努力地维持身体适当的血液灌注。

Right after the S1 sound, the aortic and pulmonic valve open up allowing blood to get pushed out to the body and this period of time is called systole.

在S1之后，主动脉瓣和肺动脉瓣打开，分别使得血液流入身体各组织以及肺部，这段时期叫做收期。

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，收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。

And they do that because your ventricles contract to build up pressure and pump blood out of the heart. This high pressure caused by ventricular contraction is called systole.

它们这样做是因你的室收以增加压力并将血液泵出。这种由室收引起的高压称收。