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I wanna figure out how blood gets from my heart, which I'm going to draw here, all the way to my toe,
这集我们要看血液怎么从心脏流向脚趾
and I'm going to draw my foot over here and show you which toe I'm talking about.
心脏在左边，脚趾画在右边，这样来表示我们讨论涉及的脚趾
Let's say this toe right here.
假设脚趾在这里
Now, to start the journey,
好，血液要流动的话
it's gonna have to go out of the left ventricle into the largest artery of the body.
从左心室流出，流入身体中最大的动脉
This is going to be the aorta, and the aorta is very, very wide across,
也就是主动脉，主动脉是非常大的一条动脉
and that's why I say it's a large artery.
实际上，是最大的一条动脉
And, from the aorta, I'm actually not drawing all the branches of the aorta,
从主动脉开始，它的分支我们不一一标明
but from the aorta, it's going to go down into my belly,
从主动脉来到腹部
and it's going to branch towards my left leg and my right leg.
然后产生左右腿的分支
So, let's say we follow just the left leg,
假设我们看左腿这边
so this artery over here on the top, it's gonna get a little bit smaller,
那么上边这个动脉就要小一点了
and maybe I would call this a medium-sized artery by this point.
这条动脉是中型大小
Ah, this is actually now getting down towards my ankle.
然后来到了脚踝
Let's say we've gone quite a distance down to my ankle,
假设到脚踝之前走了相当长的一段距离
and then, you know there are, of course, little branches,
当然，中间血管可能有不少分支
and let's just follow the branch that goes towards my foot, which is this top one.
我们就看脚趾部分的血管，也就是上边这里
Let's say this one goes towards my foot,
假设这是脚趾处的血管
and this is going to be now an even smaller artery.
这个动脉要更小一点
Let's call it small artery. Small artery.
称作小动脉
From there, we're actually going to get into what we call arterioles.
然后就来到微动脉了
So it's going to get even tinier, right? It's going to branch.
微动脉是非常非常小的动脉分支
Now, these are very, very tiny branches coming off of my small artery,
从小动脉中分出来
and let's follow this one right here, and this one is my arteriole. Arteriole.
看这里，这就是微动脉。我标一下
So, these are all the different branches I have to go through,
这些是不同的分支
and finally, I'm going to get into tiny little branches,
后来到非常小的血管分支
I'm going to have to draw them very, very skinny just to convince you that we're getting smaller and smaller.
我画的细一点，这样大家就知道血管是越来越细了
Let me draw three of them.
我画三条吧
Nah, let's draw four, just for fun. Ah, four of them,
画四条吧
and this is actually gonna now get towards my little toe cells,
这里就到脚趾细胞了
so let me draw some toe cells in here to convince you that I actually have gotten there.
在这里画一些脚趾细胞，这里就是脚趾了
Let's say one, two over here, and maybe one over here, and these are my toe cells. Toe cells.
假设这有一个细胞，这有两个，一个。这些都是脚趾处的细胞
And after the toe cells have kind of taken out whatever they need.
假设现在脚趾细胞已经得到了需要的养分
Maybe they need glucose, or maybe they need some oxygen.
比方说葡萄糖，或者氧气
Whatever they have taken out,
不管脚趾细胞吸收了什么
they are also gonna put in their wastes,
同时还要排出细胞废物
so they have, of course, some carbon dioxide waste that we need to drag back.
比方说二氧化碳，这样血管要把废物运回去
