It is from Crash Course A&P. It is at 1 minute and 23 second. Here is the context:
But even when they are functioming well, some of your immune cells are careening around your body like miniature, biological versions of Mad Max war boys. Amped up on signalling chemicals, scouring the terrain for hostiles, and covered from top to bottom in the dismembered parts of the enemies that they have vanquished.
Does that mean that they got energetic because of the signalling chemicals, or because they increased the amount of the signalling chemicals?