In the example of Na, both terms tend to support transport: the negative electric potential inside the cell attracts the positive ion and since Na is concentrated outside the cell, osmosis supports diffusion through the Na channel into the cell. In the case of K, the effect of osmosis is reversed: although external ions are attracted by the negative intracellular potential, entropy seeks to diffuse the ions already concentrated inside the cell. The converse phenomenon (osmosis supports transport, electric potential opposes it) can be achieved for Na in cells with abnormal transmembrane potentials: at +70 mV, the Na influx halts; at higher potentials, it becomes an efflux.