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So think with me for a second. Let's say you're a molecule in here. In the capillary.
大家可以想一下，假设这有一个分子
And you want to get out here, into the tissue.
想到组织中去
What are the ways you can get there?
有什么方法可以去呢？
One way would be if you actually just diffuse across. Right?
一种方法就是直接扩散过去
So one way could be diffusion.
第一就是扩散
And that would work really well if you were a molecule of oxygen or carbon dioxide.
如果是氧气或者二氧化碳分子，这种方法就很适用
It usually works well for these molecules.
对于这些分子来说，进出方式就是这样的
But let's say you're not one of those molecules
如果不是这样的分子
Let's say you're a larger molecule or charged molecule, how would you get across?
比方说是更大的分子，或者带电分子，这要怎么穿过细胞呢？
So the second way you could get across could be through a vesicle.
第二种方法，就是通过囊泡
Maybe you could get into a vesicle up here in the cell.
可以在这里进入一个囊泡
And the vesicle could transport you from being on the inside, which is where this X is,
通过囊泡在细胞中运动，大家看这个X的位置
to where it can actually get deposited on the other side,
最后来到细胞的另一边
and then of course it would slow up to make its way through the basement membrane
当然，在穿过基膜的时候速度会慢一点
but that's at least a way of getting past the cell
但这也是穿过细胞的一种方法
So this is a second approach, maybe a vesicle could carry the molecule through
第二种方法，就是借助细胞中的囊泡携带物质穿过
A third way could be through this intercellular cleft.
第三种方法，就是通过细胞间隙
Again you still have to get across that basement membrane
虽然还是要穿过基膜
but at least you can get across the cell by simply going around the cell
但至少只要绕过细胞就可以了
So maybe that intercellular cleft could be another ticket to freedom.
通过细胞间隙也是一种方式
So if you wanna get around, you can go that way that's a third way.
这是第三种方法
So what's that fourth way.
那么第四种方法是什么呢？
Now we have to go down to our second drawing, the fenestrated one.
我们看第二幅图，有孔毛细血管
Here I would suggest maybe just going through
这里我们认为
if you were that little X- maybe just going through that pore
假设X要穿过小孔
and you have to plow your way though the glycocalyx if there is some there.
就要穿过孔上的隔膜
But maybe that's another way. It's going through the fenestration.
也就是说穿过小孔
That could be another way across, right?
这也是一种方法，不是吗？
So these are four ways for things on the inside to get to the outside
这就是物质从细胞内到细胞外的四种方法
and as you look at this list that we made, these four options,
大家看这四种方法
you can see then that our idea around leakiness makes sense.
大家可以看到研究细胞通透性的重要性了
Because now- especially when you get down to the discontinuous vessels at the bottom,
尤其是对于不连续的血管来说，比方说下边这些
you've got large gaps between the cells, lots of intercellular clefts,
细胞之间存在很大的间隙，细胞间隙
you've got vesicles, that could apply anywhere diffusion can apply anywhere, and you've got fenestration.
那么通过囊泡，或者扩散，或者穿过小孔，可以很方便地运送物质
So really every opportunity for things to get out of the capillary is available in those discontinuous or sinusoid capillaries
那么将物质运出不连续毛细血管或者说血窦的方法已经列出来了
