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So what you're looking at is one of the most amazing organs in your body.
现在大家看到的是人体中一个重要的器官
This is the human heart.
这就是心脏
And it's shown with all the vessels on it.
图中画有血管
And you can see the vessels coming into it and out of it.
大家可以看到输送血液进出心脏的血管
But the heart, at its core, is a pump.
心脏本质上相当于一个泵
And this pump is why we call it the hardest working organ in our body.
可以说是身体中负荷最重的器官
Because it starts pumping blood from the point where you're a little fetus, maybe about eight weeks old,
从8周左右的胎儿开始
all the way until the point where you die.
一直到死亡，人们的心脏一直在不停工作
And so this organ, I think, would be really cool to look at in a little bit more detail.
大家看，我们仔细看一下心脏的构成
But it's hard to do that looking just at the outside.
不过从外边看，不太好辨认
So what I did is I actually drew what it might look like on the inside
我画了一个内部图
So let me actually just show you that now.
大家来看
And we'll follow the path of blood through the heart using this diagram.
我们沿血液流动的路线。来看这个图
Let me start with a little picture in the corner.
首先现在这里画一下
So let's say we have a person here.
假设这是一个人
And this is their face, and this is their neck.
这是人的脸，脖子
I'm going to draw their arms.
然后是胳膊
And they have, in the middle of their chest, their heart.
胸膛中是心脏
And so the whole goal is to make sure that blood from all parts of their body,
我们要让整个身体中的血液，包括腿中的
including their legs, can make its way back to the heart,
都能回到心脏中
first of all, and then get pumped back out to the body.
先回来，再从心脏到身体各处
So blood is going to come up from this arm, let's say, and dump into there.
从这个胳膊，来到这
And the same on this side.
这边也是一样
And it's going to come from their head.
头上的血液下来
And all three sources, the two arms and the head, are going to come together into one big vein.
胳膊和头，这三个地方的血液汇成一起来到这条静脉
And that's going to be dumping into the top of the heart.
然后进入心脏上部
And then separately, you've got veins from the legs meeting up with veins from the belly,
同时，两条腿和腹部的血液汇合
coming into another opening into the heart.
从另一个地方进入心脏
So that's how the blood gets back to the heart.
这是血液流回心脏的路线
And any time I mention the word vein,
静脉的意思就是
I just want you to make sure you think of blood going towards the heart.
大家时刻要牢记，就是输送流回心脏的血液
Now if blood is going towards the heart,
血液流回心脏
then after the blood is pumped by the heart,
然后心脏工作
it's going to have to go out to the heart.
将血液送回身体各处
It's going to have to go away from the heart.
血液离开心脏
So that's the aorta.
从主动脉离开心脏
And the aorta actually has a little arch, like that.
主动脉是有一点弓形的
We call it the aortic arch.
就叫主动脉弓
And it sends off one vessel to the arm, one vessel up this way, a vessel over this way.
从主动脉弓连接了一根血管到上臂，另一条在这个方向，一条在这个方向
And then this arch kind of goes down, down, down and splits like that.
同时还有向下走的血管，然后分成两组
So this is kind of a simplified version of it.
当然，这是心脏血管的示意图
But you can see how there are definitely some parallels between how the veins and the arteries are set up.
大家可以看到动脉和静脉之间有很多相似的地方
And arteries, anytime I mention the word artery,
动脉的意思就是
I want you to think of blood going away from the heart.
输送血液离开心脏的血管
And an easy way to remember that is that they both start with the letter A.
最简单的记忆方法就是，单词动脉(artery)和离开(away)的首字母都是a
