But before we actually define what asthmaic pressure is we have to discuss something called osmotic potential as well as osmosis. So let's suppose we have the following object, a marker. Now, anytime we take a mass, for example, the marker, and we let go, we know that mass, the marker will always move from a higher gravitational potential to a lower gravitational potential. So objects naturally move down their gravitational potential gradient from a high potential to a low potential. Now, in the same analogous way, if we take a water molecule, the water molecule will always move down its water potential gradient, also known as the zmodic potential gradient. So water naturally moves from a high osmotic potential to a low asthmatic potential.