The glomeruli filter fluid from your blood, extracting both waste products and substances your body needs — sodium, phosphorus and potassium.

肾小球过滤血液，从中摄取代谢废物和各种身体所需物质——钠、磷和钾（译者：离子？）

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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？

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