And one example of such a substance is Peh PAH, which stands for the para aminohipric acid. So this is a substance that is essentially completely cleared by our body. Actually, a small percentage of it is left over in the blood plasma, but for all approximation purposes, we can assume that all of it is actually cleared. Now, what about case number four? So here we have freely filtered, only slightly reabsorbed, and none of it is actually secreted. So let's take a look at the following example.