The term stress has been described as a nonspecific body response to a
Stressors are internal perceptions or external events that cause the body’s
autonomic nervous system to respond, to protect the body.
Internal stressors are products of emotions, and are referred to as anxieties.
External stressors result from external events or observations and involve a
sensation or fright or fearfulness.
The body’s response is the sane as for internal stressors, except that the
duration of the stress is controlled by the external event. Most external
stressors are of short duration.
The most common cause of stress is change.
Cumulative stress may become chronic depending on the intensity and
duration of the stressors.
It is interesting to note that men and women respond differently to stress.
Men often become physically or verbally aggressive, and may also use
denial as a defense mechanism.
Women on the other hand often internalize their stress, mulling it over and
over again in their minds.
Stress is a normal part of life; it is a useful response that may be termed
eustress and is considered positive.
Claude Bernard was a 19 century French biologist who discovered that the
body’s internal milieu (internal environment) changed constantly to meet
the daily demands of life.
It was Hans Selye who first conceived the theory of nonspecific reactions as
stress; he named his theory General Adaptation Syndrome (GAS)
Selye theorized that the body experiences 3 stages in its response to stress
1) The Reaction Stage
2) The Adaptation Stage
3) The Exhaustion Stage If the body successfully endures the stress encounter, the Parasympathetic
nervous system is activated and the body slowly returns to normal.
The reaction stage is composed of an alarm stage and a fight or flight
The adaptation stage takes place if stress continues for an extended length of
During this stage, body changes may take place to reduce the effect of the
stressor: a starving person has less desire for food; soldiers in extended
combat are less fearful of the death and destruction all around them.
The adaptation stage cannot continue indefinitely without harm to the body.
During the exhaustion stage, the body’s resistance to the stressor diminishes
and may completely fail, resulting in serious injury and death.
Selye also defined a resource he called adaptive energy.
This energy influences the body’s resistance to stress. It is inherited and
varies from one individual to another.
It consists of a superficial level that can be replenished at the conclusion of a
stressful event and a deep level that is not replenished and when depleted
results in disease or death.
4 body responses Selye identified as part of GAS.
- Designed to sound a warning when something is perceived to create
- Pain is part of this system as it tell us when body tissue is being
Fight or Flight
- The sympathetic nervous system prepares the body for fight or flight
- The pupils dilate. The heart rate,, pulse and respiration all increase.
- The body can only stay in the fight or flight state for a limited time.
Return to Normal
- During this stage, the parasympathetic nervous system k