Professor of psychology Christopher Vye commented for the Star Tribune on the science behind the feeling of fear.
From the article: It is that hardwired response, not our feeling of fear, that prepares us for action, said Christopher Vye, professor and chair of the University of St. Thomas' graduate school of professional psychology. Our breathing rate increases. Blood vessels in the skin and other peripheral areas constrict. That allows more blood to rush to our muscles and vital organs, which get primed with oxygen and nutrients. The amygdala nudges the command center of the brain, the hypothalamus, to produce epinephrine — otherwise known as the darling of daredevils, adrenaline.
"What's cool is that the whole system is preparing us for maximum performance," Vye said.