Two of these steps, step one and two, take place in the matrix of the mitochondria of that liver cell. And the other three steps three, four and five take place in a cytoplasm of that hepatocyte, the liver cell. So let's suppose we have metabolism of amino acids that takes place inside the hepatocide. Now, this also takes place outside the liver, but ultimately all the ammonium ends up inside the liver, inside the matrix of that mitochondria. And so the extra ammonium basically is used. It's combined with carbon dioxide that comes from bicarbonate, as we'll see in just a moment.