When an individual is faced with a threat, an area of the brain called the
amygdala is activated which is associated with sensory information. It
sends a message to the hypothalamus which is in charge of the stress
response and this communicates to the rest of the body through the
sympathetic nervous system (SNS).
Responses to acute stress are produced by the flight or fight response via
the SAM pathway. The SNS sends a message to the adrenal medulla which
releases adrenaline into the bloodstream, increasing heart rate and blood
pressure which in turn increases oxygen levels. This means the body has
more energy available to respond to the stressor. Once the threat is gone,
the parasympathetic nervous system (PNS) dampens down the stress
response and restores the body to its normal state.
Chronic stress is regulated by the HPA system. The hypothalamus
releases corticotrophin into the bloodstream which arrives at the pituitary
gland which then releases ACTH and this moves to the adrenal glands.
This stimulates the release of cortisol which gives a quick burst of energy
and lowers pain sensitivity but impairs cognitive performance and
weakens the immune system.
The stress response assumes that everyone responds identically to a
stressor. However, there are gender differences in the behaviour
responses to stress. Taylor argues that due to females having a greater
amount of oxytocin, they are more likely to ‘tend and befriend’ during
stressful episodes whereas men behave more aggressively. Therefore, a
body’s response to stress may vary from person to person.
However, Von Dawan et al argues that men do also act in cooperative
ways and not just in an aggressive way. It is argued that this explains why
in times of crisis, such as 9/11, that humans help each other. It is argued
that this is because humans are social animals and so this suggests that a
body’s response to stress should be the same for everyone.
However, Gray argues against the flight or fight response as being the
first part of the stress response, he argues that many animals, including
humans, freeze in response to a threat or stressor in order to determine
danger. Their heart rate and blood pressure may increase but it may not
lead to a flight or fight response, which is different to what the model
suggests.
However, there is considerable variation in the level and type of hormones
released by different people and in response to different stressors and
therefore it is not a simple physiological process as stated previously.
Some individuals without adrenal glands need hormonal supplements to
survive stress and so is not as easy for some as others.