And the stroke volume is a fraction of the total volume.

每搏输出量只是心室总容积量的一小部分。

The heart rate is pretty intuitive, but the stroke volume's a little tricky.

心率非常直观，但每搏输出量的计算有点棘手。

In this case again the stroke volume is low, but the ejection fraction's normal... how's that?

在这种情况下，每搏输出量低，但射血分数显示正常，为什么会这样呢？

On the other hand, left ventricular stroke volume is decreased during inspiration.

另一方面，在吸气过程中，左心室每博量减少。

Here we see that the end-systolic volume is closely related to stroke volume.

这里，我们看到收缩末期容积与每博输出量密切相关。

When heart rate and stroke volume increase, we see an increase in cardiac output.

当心率和每博输出量增加时，我们发现心输出量增加。

Doctors can also monitor the stroke volume to gather clues about the strength of your heart.

医生还可以监测每博输出量，以收集有关心脏力量的线索。

Therefore, we see that a decreased end-systolic volume indicates an increase in stroke volume.

因此，我们看到收缩末期容积减少，表明每博输出量增加。

The stroke volume can also be increased or decreased.

每博输出量也可以增加或减少。

One factor that can increase the stroke volume is an increased end-diastolic volume.

可增加每博输出量的一个因素是舒张末期容积增加。

Therefore, we see that an increase in end-diastolic volume, or 'preload, ' results in an increased stroke volume.

因此，我们看到舒张末期容积或" 预负荷" 增加导致每博输出量增加。

And, from our equation, we see that this means you either increased your heart rate or your stroke volume or both.

从我们的方程式中，我们发现这意味着你或者增加了心率，或者增加了每博输出量，或者两者兼而有之。

In other words, increased afterload results in increased end-systolic volume and less blood leaving the heart, or decreased stroke volume.

换言之，后负荷增加会导致收缩末期容积增加，离开心脏的血液减少，或每博输出量减少。

Another important influence of end-systolic volume, and therefore stroke volume, is how much pressure exists in the arteries leaving the heart.

收缩末期容积以及每博输出量的另一个重要影响是离开心脏的动脉中的压力。

In this lesson, we will look at some of the factors that influence your heart rate and stroke volume.

本节课，我们将研究一些影响心率和每博输出量的因素。

Therefore, if something increases or decreases the heart rate or stroke volume, it will increase or decrease the cardiac output, respectively.

因此，如果某因素增加或降低了心律或每博输出量，则将分别增加或降低心输出量。

A decreased stroke volume can occur when there is an increase in the resistance in the arteries leaving the heart.

当离开心脏的动脉阻力增加时，每博输出量就会减少。

Now that we know what influences the heart rate, let's look at some of the factors that influence the amount of blood pumped during each heartbeat, which is your stroke volume.

现在我们知道了什么会影响心率，我们看一下影响每次心跳期间的泵血量（即每博输出量）的一些因素。

Two scientists named Frank and Starling noticed that the increase in end-diastolic volume, or preload, results in an increased stroke volume and more blood being pumped out of the heart with each heartbeat.

两位名为Frank和Starling的科学家注意到，舒张末期容积（即预负荷）的增加导致每搏输出量增加，并且每次心跳都会将更多的血液从心脏中泵出。