"47 Section 3.4 Your Bod ies Response to Stress Fight or Flight Response When we experience excessive stress, either from internal worry or external circumstance, a bodily reaction called the \"fight - or - flight\" response will be triggered. Harvard physiologist Walter Cannon original ly defined it. The response system represents the genetic impulse to protect ourselves from bodily harm, but also can result in negative health effects. According to Cannon’s theory, during stress - response processes, the sympathetic nervous system increase s the heart rate and releases chemicals to prepare our body to either fight or flee. When the fight - or - flight response system get activated, it tends to perceive everything in the environment as a potential threat to survival. In modern life, we do not ge t the option of \"flight\" very often. We have to deal with those stressors all the time and find a solution. When you need to take an SAT test, there is no way for you to avoid it; sitting in the test room for five hours is the only choice. Lacking the \"fli ght\" option in stress - response process leads to higher stress levels in modern society. Section"