ADRENALINE

When tension runs high and adrenaline is secreted into your body some crazy things can happen — sometimes called the fight-or-flight response:

Adrenaline: a hormone and chemical neurotransmitter (4-[1-hydroxy-2-(methylamino)-ethyl]-1,2-benzenediol) produced in the adrenal medulla. It causes bronchodilation, vasoconstriction, CNS stimulation and mydriasis.

• Your heart rate increases. And specifically, your body starts sending blood to all your big muscles and diverts it away from “non-critical” parts of your body, like your brain, immune system, and digestive system.
• Your pupils dilate and you get tunnel vision. Quite literally, adrenaline also reduces your peripheral vision, which together with your big, wide pupils helps you focus on what lies ahead.
• Your body gets ready. In addition to the rising heart rate, your body starts turning lots more stuff into sugar, raising your blood sugar level and filling you with energy.