When we experience excessive stress, whether from internal worry or external circumstance, a bodily reaction is triggered, called the “fight or flight” response. Originally discovered by the great Harvard physiologist Walter Cannon, this response is hard-wired into our brains and represents a genetic wisdom designed to protect us from bodily harm. This response actually corresponds to an area of our brain called the hypothalamus, which, when stimulated, initiates a sequence of nerve cell firing and chemical release that prepares our body for running or fighting. When our fight or flight system is activated, we tend to perceive everything in our environment as a possible threat to our survival.


By its very nature, the fight or flight system bypasses our rational mind, where our more well thought out beliefs exist and moves us into “attack” mode. This state of alert causes us to perceive almost everything in our world as a possible threat to our survival. As such, we tend to see everyone and everything as a possible enemy.  In this situation our hormonal glands start to release hormones like adrenaline, noradrenaline and cortisol into our bloodstream.

These patterns of nerve cell firing and chemical release cause our body to undergo a series of very dramatic changes. Our heartbeat increases, to pump the blood to the necessary parts of the body quickly, breathing becomes more shallow and rapid as the body tries to obtain more oxygen, the liver releases more stored sugar into the bloodstream to increase the energy level needed for action, our pupils let more light and other senses become heightened also our blood is shunted away from our digestive tract and directed into our muscles and limbs. To protect our body against excessive bleeding blood vessels to the skin being constricted reducing any potential blood loss. Sweat glands also open, providing an external cooling liquid to our over-worked system. (This makes the skin look pale and clammy).


(Gleitman, et al, 2004) formulated the following list of immediate physical reactions associated with a preparation for violent muscular action.  This list is not exhaustive but rather covers the main categories of expected responses:


  • Acceleration of heart and lung action
  • Inhibition of stomach and intestinal action
  • General effect on the sphincters of the body
  • Constriction of blood vessels in many parts of the body
  • Liberation of nutrients for muscular action
  • Dilation of blood vessels in muscles
  • Inhibition of Lacrimal gland (responsible for tear production) and salivation
  • Dilation of pupil
  • Relaxation of bladder
  • Inhibition of erection
  • Auditory Exclusion (loss of hearing)
  • Tunnel Vision (loss of peripheral vision)

Unfortunately, we are historically too close to the original value of this primitive response for our systems to have evolved to a more appropriate use of it, and many of life’s stresses trigger this response. The surprises and shocks of modern living leave us in a permanent state of arousal that takes its toll on our bodies.

Wath this video to understand the Fight or Flight Response:


Tags: , , ,