And actually, a question that might come up, I just explained, the sodium channel, you might say, well, how do potassium channels work then, because I can understand how you can filter something big out, but how do you filter out something small.

实际上，可能大家会问一个问题，我刚解释过，钠离子通道，你可以说，好吧，那么钾离子通道该如何起作用呢，因为我可以理解你是如何把大东西过滤掉的，但是你如何把小东西过滤掉呢？

麻省理工公开课 - 化学原理课程节选

What all of these channels have is what's called a selectivity filter, so this filter filters out the type of ion that's going to be allowed through.

这些离子通道都有的一部分,就是所谓的选择性过滤器，这个过滤器,会滤过允许穿过的离子。

麻省理工公开课 - 化学原理课程节选