Stress is a terminology that has not been defined by any field of research; its contextual
basis provides the real meaning for it. (Kemeny, 2003) It has various effects, physiologically
and psychologically on the individual under stress. However, different stressors, cognitive
appraisals and physiological factors combined as a whole have an impact on the way an
individual would respond to a certain scenario. Now the physiological and psychological
effects stressors pose, taking into consideration cognitive appraisal and different
perceptions of individuals and the health implications related to it.
Through her findings, Kemeny (2003), points out the key fact that the motor receptors in the
brain respond to different stressors in distinctive ways and the one-type-fits all model
cannot be used to analyse the discharge of cortisol into the body system and the
physiological response to it. She has further illustrated how a wide array of physiological
systems have responded differently to stressors, and this has had an impact on majority of
the body organs and functional systems, especially the autonomic nervous system, leading
to HPA activation, further effects on the immune system and the health implications
associated with these stressors. She does point out that cognitive appraisal plays a major
role on the outcome to the response to these stressors as well, and therefore all external
physiological factors had to be continuously monitored to see the changes. (Kemeny, 2003)
Extensive research done on animals has shown how powerful the effects of exposure to
stressors are on a variety of physiological systems. It further goes to show that physiological
systems change in response to different stressors, having adverse long-term health effects.
(Miller, Cohen, & Ritchey, 2002) This is all based on the individual and how they react to the
stressor and whether they deem it a threat or something conquerable.
Effect on the Autonomic Nervous System
The body's nervous system is divided into the central and peripheral nervous system. The
CNS comprises of the brain and the spinal cord and the peripheral constitutes of the
autonomic and somatic nervous systems. The autonomic sensory system (ANS) is the first to
respond to a stressful stimulus. It has two divisions, the Sympathetic and parasympathetic
nervous systems that react to stressors and cause physiological changes.
During stress, the SNS creates what is known as the "fight or flight" reaction. The SNS
indicates the adrenal organs to discharge hormones called adrenalin and cortisol. These
hormones cause the heart to beat at a faster rate, the breathing to increase and deepen,
and blood vessels all around the body to dilate to allow more blood flow and glucose levels
in the body to rise to provide energy. As the SNS keeps on triggering physical responses, it
causes a wear-and-tear on the body. This process is so quick that even the brain does not
react immediately to the trigger, but if this response by the body is not controlled, it can
pose long term health complications.
Effect on the Hypothalamic-Pituitary-Adrenal Axis
Stress (whether physical or mental) causes neurons in the hypothalamus to discharge a
hormone known as corticotrophin-releasing hormone (CRH). CRH is then transported to the
pituitary organ which then secretes an alternate hormone, adrenocorticotropic hormone
which invigorates the adrenal cortex (some piece of the adrenal organ). The amygdala which
is involved in the "fight or flight setup" of the body, enacts the HPA axis to set in motion the
response need to overcome the threat. The other vital systems that are affected by
stressors include cytokines, metabolic hormones and the autonomic sensory system.
Effects of stressors on health
Stress does tend to have an impact on one’s health, but if the exposure to stressors is long-
lasting, it can affect the long-term functionality of the nervous system in a body. This is
because chronic stress can cause the HPA axis to continue releasing cytokines that cause
unnecessary inflammation in the body and make a person feel like they are sick.
Furthermore, stressors also cause people to become vulnerable to respiratory infections
such as pneumonia, flus and colds, especially if the individual already has a viral infection.
Many researchers assume that stressors have a uniform effect on the physiological
processes of a body, and that every individual exposed to the same kind of stressor will
react in the same manner, as stereotyped by the generality model. Kemeny (2003) states
that there is not much truth to this as distinctive stressors have shown to elicit different
responses from individuals and their physiological and psychological effects are also
different. This is stipulated in the specificity model which propagates that threats are
perceived differently by different individuals based on their perception of what is a threat. I
Nonetheless, stressors pose multitude of health risks to individuals and chronic stress
causes a major problem in nearly every system in one's body. It can raise pulse, cause
suppression of the body's immunity, increase the chance of heart attack and stroke, cause
infertility and at times even speed up the aging of the body. Long term stress can even
affect the brain neurology and cause you to be depressed and anxious throughout.
Role of Cognitive Appraisal
Lazarus and Folkman (1986) propagated a theory of stress that suggested that perception of
stress by an individual will determine the physiological response they give to it. They
emphasise that a stressor can be perceived as a controlled threat by one person and
uncontrollable by another and this is what will determine the overall outcome and
psychological effects that result from it. If one perceives exposure to a certain stressor as
something they cannot cope with, then they will be anxious and concerned about it. This is
all to do with cognitive appraisal, where one’s motor neurones in the brain that are incharge
of thinking, and making decisions, perceive it as a threat and send a signal to the
hypothalamus to trigger cortisol production in the body to get the individual ready for the
challenge.