So Because We Have A Larger Opening about ten angstroms on the inside side than on the outside side, where it's about three angstroms. So this internal cavity will have enough space to actually fit those same water molecules that exist on the inside cytoplasmic side of that cell. Now, why is that important? So about two thirds of the central cavity is filled with water, and that makes an aqueous environment. But why is that important? Well, that's important because these K plus ions, the potassium ions, actually interact with the water molecules to form a more stable structure.