It prepares the bodyto face the threat and fight or to flee. The warthog's heart is...

[narrator] It prepares the body
to face the threat and fight or to flee. The warthog's heart is racing
and breathing speeds up. Lung passages expand
and certain blood vessels dilate, all to make sure plenty of oxygen
gets to the muscles needed to flee. Those muscles tense, ready for action. The warthog's pupils dilate so its eyes
can take in more of the scene. And then its peripheral vision shrinks
to focus on the lion in front of it. Other systems get shut down. You got better things to do
with your energy than digest breakfast or worry about reproduction
or something like that