Imagine you’re walking down the street in the city; perhaps you’re on your way to a yoga class, meeting friends at a cafe, or heading back to your car after a long day at work. Suddenly, you hear commotion in a shop along the sidewalk and somebody bursts out of the door with a weapon. This is the definition of a traumatic experience.
He or she makes eye contact with you and begins to move toward you in a menacing manner. You see sunlight glinting off of the blade in the hand of his or her hand. How you react to this situation is determined in less than a second, and is outside of your concious control.
First, the image of this person is received by your eyes, and relayed to an area of the brain called the visual cortex (at the posterior of the skull). The signal is then sent to your amygdalae (near the center of the brain) for interpretation. The amygdalae interpret this situation as a threat to the organism which houses them and intitiate the sympathetic nervous system. The amygdalae signal the adrenal glands (atop your kidneys) to secrete epinephrine into your bloodstream, which primes your body for “fight or flight.”
The pupils of your eyes dilate to take in more light and information, your heart rate and respiration both accelerate, and your muscles are primed for action. To be realistic, most people will not stay for a fight, especially if the attacker is larger and/or armed. It’s most likely that you will fight only until you find an escape route.