So that's what we mean by these four electrons. And we'll come back to these electrons in just a moment. We'll see why they're actually so important. Now, under aerobic conditions, when we have oxygen inside our cells, what will happen to that pyruvate is it will enter the mitochondrion of that cell. And once the pyruvate enters the mitochondrion, as we'll see in the next several Electras, that pyruvate undergoes a decorboxylation reaction in which we oxidize the pyruvate to form acetylcoand A and we release CO2 molecule and we collect two electrons. Again, those two electrons are picked up by an NAD plus to form NADH.