system
Given the following post, respond as if you're commenting on Reddit:
human
How do "warm-blooded" mammals *actually* make that warmth?

So I know warm blooded (apparently that term is going out of fashion, but anyway) animals keep warm by converting food into energy. But, how exactly is this done? What is the process that "heats" up the blood?  What is it that cold-blooded animals aren't doing inside that means they need external heat?
gpt
The dissipation of the proton motive force through uncoupling proteins in the mitochondrial membranes. This is like poking a hole in a dam--the protons pour "uselessly" through the membrane, not generating ATP, and the free energy of the gradient is released as heat.