So in this particular case, we saw that all the sodium ions can spontaneously move down their electrochemical gradient, just like the market can move spontaneously down its gravitational potential gradient from a high to a low. We have this barrier, the hydrophobic core, that prevents the movement of those sodium ions, just like my hand prevents the movement of this marker down its potential gradient. And channels essentially remove that hydrophobic core and allow those ions to move down that passageway that does not contain that hydrophobic core. And so what that means is this type of movement is known as facilitated diffusion. Now, since channels move ions and molecules down their electrochemical gradient, no energy is actually used. And so what that means is this mode of transport is known as passive transport.