Selye's General Adaptation
Syndrome describes how the body
adapts to stressors.
As a doctor he notices that patients with a variety
of illnesses all shared certain symptoms. Later in
his career while researching the effects of
hormones on rats he notices that they too shared
certain responses regardless of the hormones they
were given.
These observations led him to
develop his theory by exposing rats
to various stressors such as extreme
temperatures and surgical injury and
monitoring their physiological
responses.
Alarm
The stressor activates the
hypothalamus which triggers
the HPA Axis and the
autonomic nervous system
The ANS causes
adrenaline production
which leads to
readiness for "fight or
flight".
Physiological reactions;
increased heart and breathing
rate, release of sugars to
generate engery. If stressor
disappears, body returns to
normal.
Resistance
If the stressor persists, the
body continues producing
adrenaline and cortisol.
Attempting to adapt to the
stressor the PNS cuts in and
the body appears to cope.
Elevated hormone levels
take their toll and the
body's ability to resist
diminishes.
Physiological Reactions;
increased blood pressure, sugars
now stored to conserve energy.
The HPA axis is heavily involved
in the first two stages as it
governs the physiological
response to stress.
Exhaustion
If the stressor persists
hormone levels remain
high, the body can no
longer cope.
Physiological Reactions; Damaged
adrenal glands, a weakened immune
system. As a result defences become less
effective and stress related illnesses occur
such as heart disease and ulcers. Selye's
rats died.