And notice that when the PH of the solution is 4.75, which is the same as the PKA, the curve has the flattest slope, and the flattest slope corresponds to the region with the least change in PH. So what do we conclude from this discussion? Well, basically, buffer functions best at PH values that correspond to the PKA of that asset that we're using in the first place. So what that means in layman terms is if we want to have a solution that basically is at a specific PH and we want it to remain at that PH, then we have to find an acid that will serve as that buffer system that has a PK value that is equivalent to that particular PH value. And that's exactly what our body does. So we have different types of biological buffer systems in place.