So if Km is this x value, the concentration of the s, then if we check out the Y coordinate, that will be exactly midway between the zero velocity value and the VMAX value as shown in the following diagram on the following curve. So we see that when Km is much, much smaller than the concentration of the substrate in that environment, we see that our enzyme mixture is operating at a maximum velocity. And this is equivalent to saying that all the active sites in the enzyme mixture are filled and so the enzyme's velocity is at a maximum. Now, what exactly happens under normal physiological conditions inside our body and inside our cells? Well, typical physiological conditions basically involve a relatively low concentration of substrate. So under typical physiological conditions inside our cells, the substrate concentration is usually very low and the substrate concentration is usually between zero and the Km value.