Effects of Stress
The Fight or Flight Response
Stress can be defined in many ways, but the best way to
describe it is the “fight or flight response”. In a situation
of stress the human system will respond in the following
manner. First, the “sympathetic” segment of the body’s
autonomic nervous system is activated, causing the
adrenal gland to produce and secrete norepinephrine and
epinephrine (adrenaline) into the bloodstream. Second,
the pituitary gland will stimulate the adrenal cortex
which secretes cortisol, the “stress hormone” identified
by Hans Seyle’s stress model[1, p. 179]. As a result of this
release of adrenaline, cortisol and other hormones into
the bloodstream, several events are set in motion. First,
the pulse rate quickens and blood pressure rises in an
attempt to increase blood flow to the major muscle
groups such as the shoulders, legs and arms. A side effect
to this is that blood flow is diverted away from
extremities such as the hands and the feet. Second,
breathing becomes shallow and rapid in an attempt to
increase oxygen levels in the body. Finally, blood sugar
production increases to quicken metabolism to release
fats and energy into the bloodstream.
Type A versus Type B
Recent research has shown that individuals who suffer
from high degrees of stress (type A behaviour) have a
significantly different “sympathetic” nervous system
reaction when compared with low-stress individuals
(type B behaviour)[2]. Type A individuals suffer from a
high and uncontrolled release both of adrenaline and
cortisol with a relatively long recovery time. Negative
side effects of excessive cortisol secretion include
increased fat levels in the bloodstream, increased
breakdown of lean body tissue for energy conversion, and
increased levels of acidity in the stomach. Cortisol also
decreases the amount of catecholamines in the brain,
which increases anxiety and depression. Catecholamines
also enhance the activity of blood cells which fight
infection. Not surprisingly, members of families with
histories of heart dise