Fight or Flight Response: Our Default Mode of Existence

The fight or flight response occurs oin the body in response to a perceived attack, threat or danger to survival.

Animals react to harmful events or threats by triggering the activity of the sympathetic division of the autonomous nervous system activating the release and use of epinephrines and norepinephrines to prepare the body for a fight or flight. In the process, stress hormone called cortisol is produced by the adrenal glands. Cortisol increases blood pressure and blood sugar on one side and it suppresses the immune system on the other.

Cortisol turns fatty acids to energy which combined with additional blood sugars cause a flood of energy for muscles to fight or flee as fast one can. Fight or flight is accompanied by other physical reactions such as:

  • Increase in heart rate,
  • Increase in breathing rate,
  • Increase in metabolic rate or rate of expenditure of energy,
  • Slowing down or stopping of digestion, thus slowing or stopping the rate of energy production,
  • Liberation of metabolic energy sources including fatty acids and glycogen for muscular action,
  • Constriction of blood vessels in many parts of the body increasing blood pressure,
  • Dilation of blood vessels for muscles,
  • Loss of hearing,
  • Loss of peripheral vision,
  • Dilation of pupils,
  • Relaxation of bladder,
  • Inhibition of erection,
  • Disinhibition of spinal reflexes,
  • Shaking,
  • Increased muscle tension,
  • and more ...

In addition, there are complex emotional and cognitive reactions that inevitably accompany the above list of physical reactions.

The fight or flight response was identified by Dr. Walter B. Cannon, M.D. of Harvard Medical School in about 1920. It is closely associated with the activity of sympathetic division of the autonomous nervous system, feeling of stress and stress hormone called cortisol.

We do not need to make an effort to elicit the fight or flight response from our body. It is our natural default mode of existence.