And all ion channels are selective for a single type of ion, and we can think about how that selectivity takes place, and that's where this idea of atomic radius is going to become very important.

所有的离子通道都是仅对某一种离子具有选择性的，而我们可以来想一想这种选择性是如何发生的，这也就是原子半径这个概念将会变得，非常重要的地方。

麻省理工公开课 - 化学原理课程节选

All cell membranes have these channels within them, and under their resting conditions sodium is moving from outside to inside, potassium's moving from inside to outside.

所有细胞膜上都有这种通道结构,在静息状态下,钠从细胞外流向细胞内,钾从细胞内流向细胞外

耶鲁公开课 - 生物医学工程探索课程节选