Epinephrine (sometimes caled adrenaline) is a critical hormone for the fight/flight response agains threats. When epinephrine is secreted, it reaches many organs, among them the liver. When liver senses epinephrine it release glucose in the bloodstream, which will be criticar for the muscles to act. Wether the response is fight or flight, muscles will need glucose for the intense inminent effort. That is, liver cells provide the necessary fuel (in this case glucose) for the body to move, either to fight, or to flight.