Brandon's emotional response probably resulted from neural impulses that "the sympathetic nervous system triggered the fight or flight responses."
The fight-or-flight reaction, otherwise called the acute stress response, alludes to a physiological response that happens within the sight of something that is startling, either rationally or physically. The reaction is activated by the arrival of hormones that set up your body to either remain and manage a risk or to run away to safety.
The term 'fight-or-flight' represents to the decisions that our antiquated precursors had when looked with a threat in their condition. They could either battle or escape. In either case, the physiological and mental reaction to push readies the body to respond to the peril.