What is the Stress Response?

Today’s post is Part 1 of a 3 part series on stress. This blog post will look at what the stress response is, and how it affects the body.

Stress Defined

The term “stress” gets used lots – many people talk about being “stressed-out”. But what is stress? What does it really mean? At its core, stress, or the stress response, is a set of physiological reactions to a real or perceived threat.

Real threat: you get in an argument and your opponent pulls out a knife; you’re out walking in K-Country and a bear lumbers onto your path; or your car skids out on black ice and it heading for the ditch… These are examples of an actual physical threat to your health and safety.

Perceived threat: your boss dumps another deadline on you; you wake up April 30 and realize you haven’t started your tax return; or you have to give a presentation (and you hate public speaking)… These are examples of a perceived threat; they are scary and “stressful” but you are in no immediate danger of physical harm.

Stress Response

Your body responds the same way to both real and perceived threats. In both cases the “Fight or Flight” mechanism governed by the Sympathetic Nervous System becomes engaged.  When this happens the brain sends direct nervous signals and chemical messengers (hormones) to various parts of the body leading to specific changes in the body.

The “fight or flight” response is a set of reactions to a fearful stimulus.

In addition to the changes shown in the picture some other changes include: increased sweating, decreased tearing of the eyes, decreased saliva, relaxation of the bladder, decreased peripheral vision, and goose bumps.

Reason for the Stress Response

All of these changes are to get your body ready to respond to the threat. That response may be aggression and fighting off the threat or fear and running from the threat. In either case your body needs to be ready to spring into action. It has been found that men and women often respond differently with men tending more toward aggression and women tending more toward flight or avoidance.

The “Fight or Flight” stress response is a short term change.  It is mediated by adrenaline, a very Yang type hormone.  You get a short burst of “super powers” to survive the immediate threat.  Once you have fought off your attacker, or fled the scene, the stress response ceases.  Adrenaline is very fast-acting, but has a short duration of action.

The “Fight or Flight” stress response was valuable in an evolutionary sense.  If we couldn’t run away from tigers and survive to have kids the human race would have died out.  However, in today’s comfortable First World nations we don’t encounter real threats too often.  Most of the threats we encounter on a daily basis are perceived threats.  In the next post of this series I will talk about the long-term changes that occur when perceived threats are on-going.


Common Signs and Sympotons of Stress: The American Institute of Stress. (n.d.). Retrieved February 18, 2015; from http://www.stress.org/stresseffects/

Maté, G. (2003). When the body says no: Understanding the stress-disease connection. Hoboken, NJ: J. Wiley. Milford, F. (2005).

Stress Symptoms, Signs, and Causes. (n.d.). Retrieved from http://www.helpguide.org/articles/stress/stress-symptoms-causes-and-effects.htm

What Is Stress? (n.d.). Retrieved from http://www.stress.org.uk/What-is-stress.aspx

Sympathetic Response. (n.d.) Retrieved from https://www.boundless.com/physiology/textbooks/boundless-anatomy-and-physiology-textbook/autonomic-nervous-system-14/functions-of-the-autonomic-nervous-system-142/sympathetic-responses-750-9204/


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