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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，假設這有一個分子
And you want to get out here, into the tissue.
想到組織中去
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?
一種方法就是直接擴散過去
So one way could be diffusion.
第一就是擴散
And that would work really well if you were a molecule of oxygen or carbon dioxide.
如果是氧氣或者二氧化碳分子，這種方法就很適用
It usually works well for these molecules.
對于這些分子來說，進出方式就是這樣的
But let's say you're not one of those molecules
如果不是這樣的分子
Let's say you're a larger molecule or charged molecule, how would you get across?
比方說是更大的分子，或者帶電分子，這要怎么穿過細胞呢？
So the second way you could get across could be through a vesicle.
第二種方法，就是通過囊泡
Maybe you could get into a vesicle up here in the cell.
可以在這里進入一個囊泡
And the vesicle could transport you from being on the inside, which is where this X is,
通過囊泡在細胞中運動，大家看這個X的位置
to where it can actually get deposited on the other side,
最后來到細胞的另一邊
and then of course it would slow up to make its way through the basement membrane
當然，在穿過基膜的時候速度會慢一點
but that's at least a way of getting past the cell
但這也是穿過細胞的一種方法
So this is a second approach, maybe a vesicle could carry the molecule through
第二種方法，就是借助細胞中的囊泡攜帶物質穿過
A third way could be through this intercellular cleft.
第三種方法，就是通過細胞間隙
Again you still have to get across that basement membrane
雖然還是要穿過基膜
but at least you can get across the cell by simply going around the cell
但至少只要繞過細胞就可以了
So maybe that intercellular cleft could be another ticket to freedom.
通過細胞間隙也是一種方式
So if you wanna get around, you can go that way that's a third way.
這是第三種方法
So what's that fourth way.
那么第四種方法是什么呢？
Now we have to go down to our second drawing, the fenestrated one.
我們看第二幅圖，有孔毛細血管
Here I would suggest maybe just going through
這里我們認為
if you were that little X- maybe just going through that pore
假設X要穿過小孔
and you have to plow your way though the glycocalyx if there is some there.
就要穿過孔上的隔膜
But maybe that's another way. It's going through the fenestration.
也就是說穿過小孔
That could be another way across, right?
這也是一種方法，不是嗎？
So these are four ways for things on the inside to get to the outside
這就是物質從細胞內到細胞外的四種方法
and as you look at this list that we made, these four options,
大家看這四種方法
you can see then that our idea around leakiness makes sense.
大家可以看到研究細胞通透性的重要性了
Because now- especially when you get down to the discontinuous vessels at the bottom,
尤其是對于不連續的血管來說，比方說下邊這些
you've got large gaps between the cells, lots of intercellular clefts,
細胞之間存在很大的間隙，細胞間隙
you've got vesicles, that could apply anywhere diffusion can apply anywhere, and you've got fenestration.
那么通過囊泡，或者擴散，或者穿過小孔，可以很方便地運送物質
So really every opportunity for things to get out of the capillary is available in those discontinuous or sinusoid capillaries
那么將物質運出不連續毛細血管或者說血竇的方法已經列出來了
