Stress: Friend or Foe?

     Today is the 16th anniversary of my fellow firefighter's death.  In the years following this incident I was left with what felt like a war-torn psyche.  PTSD is a disorder of the mind with distinct signs and symptoms. However, what is the biological significance of both acute and chronic stress on the body?  Our journey continues with an examination of this process through the work of noted endocrinologist, Hans Selye. 

     The remainder of this post will flow like a biology textbook, but it is necessary to summarize the scientific literature as it is described.  I promise to break all of this information down into lay terms in future posts (believe it or not this also relates to exercise).  I leave you with another video that will describe the effects of stress on the body.  Please leave any questions on this subject matter in the comments section of the blog post.

     Stress is an every day event in our lives, be it a physical or psychological event that creates both internal and external changes in the body (Gould, 2006, p. 218).  For example, a stressor can be trying to escape from a wild animal as did our ancestors, the end of a long term relationship, or fear of hospitalization.  Hans Selye defined this fight or flight as the General Adaptation Syndrome and separated it into three distinct phases: alarm, resistance, and exhaustion (ACHS, 2012, p. 223).

     The alarm phase begins when an individual is exposed to a stressor such as walking around a corner and someone scares you by saying “boo”.  Immediately, the brain directs the hypothalamus to activate the adrenal medulla to release the hormone adrenaline (epinephrine) which causes the following physiological responses: an increase in heart rate, diversion of blood from the less vital organs such as the skin and the digestive system to preserve the core (heart, lungs, and muscles), and respirations increase to provide additional oxygen to these same critical organs (ACHS, 2012, pp 221, 223, 225).  Additionally, the pituitary gland signals the adrenal cortex to increase cortisol production that causes the liver to release large amounts of stored glucose in order to boost energy levels (ACHS, 2012, p. 223).  The sum effect of these physiological responses prepares the body to respond to a perceived threat.  According to the ThinkQuest library, the alarm phase lasts only a few seconds which is the amount of time it takes for the release of adrenaline and its physical effects to manifest (2012).

     While the alarm phase prepares the initial response, it is in the resistance phase that the body continues to adapt to the stress and operate at peak performance (ACHS, 2012, p. 223).  As the glucose stores are depleted, the hormone cortisol converts protein to a secondary energy source.  Additionally, the hormone aldosterone will cause sodium reabsorption in order to maintain an elevated blood pressure.  ThinkQuest library notes that it is in the resistance phase where the body learns to adapt to a stressor and handle it better when faced with similar circumstances.  For example, the body will adapt to the cyclic pain of chronic disease (2012).

     Although resistance allows the body to adapt to a stressor, it is in the exhaustion phase where the fight ends.  This is the point of the physiological battle where the body has used up all of its reserve forces and can no longer keep pace.  Cortisol and aldosterone levels fall and lead to hypoglycemia and erratic blood pressure respectively (ACHS, 2012, p. 223).  In the end, a person no longer has the strength to fight the stressor and becomes tired and run down (Think Quest Library, 2012).

     All three phases of the General Adaptation Syndrome are part of a normal response to stress.  A healthy response can be the elation felt upon learning that one has become a new aunt or uncle.  This initial reaction will wear off and the body returns to a state of calm.  However, if one experiences a chronic negative stressor with a sustained resistance phase, the body becomes more susceptible to heart disease, diabetes, and cancer (ACHS, 2012, p. 223) with a suppression of the immune system response (Gould, 2006, p. 222).

 

 

References

American College of Healthcare Sciences. (2012). General Adaptation Syndrome (Stress): Fight or Flight. In Aroma 203 course e-textbook. Portland: American College of Healthcare Sciences.

Gould, B. (2006). Pathophysiology for the Health Professions (3^rd ed.).  Philadelphia: Saunders-Elsevier.

General Adaptation Syndrome. (2012, February 27). Retrieved from the Oracle Education Foundation ThinkQuest library: http://library.thinkquest.org/C0123421/gas.htm

 

 

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