Biological Explanations of Stress (DP IB Psychology)
Revision Note
General Adaptation Syndrome (GAS)
When we are under threat, our body immediately begins to prepare itself for either fighting the threat or running away: the fight or flight response
The fight or flight response is an inherited physiological response designed to protect us from danger
Hans Selye (1956) developed the General Adaptation Syndrome (GAS) to explain the fight/flight response, proposing that the body reacts in the same way to all stressors
Selye experimented on rats, but GAS has been supported by research into human stress
GAS is still used today to explain how stress leads to an exhaustion of the body’s resources, leaving us vulnerable to illness
Stage 1 - Alarm
the hypothalamus activates the sympathetic nervous system (SNS) and the adrenal glands
corticosteroids (adrenaline, noradrenaline and cortisol ) are released into the bloodstream
heart rate and blood pressure increase in readiness for a physical fight-or-flight response
Stage 2 - Resistance
if the stressor continues, the fight-or-flight response ceases but output of cortisol from the adrenal cortex continues and the adrenal glands may become enlarged
because one of the results of the activation of the SNS is the suppression of the immune system, the body is not able to fight off colds and flu during this time.
Stage 3 - Exhaustion
if the stressor continues for a long time, the body’s resources are reduced and alarm signs, such as increased blood pressure, may return
the immune system is depleted
it is in this stage that major health effects, such as cardiovascular disease, may be seen
Examiner Tip
Mnemonics can help you remember the order of the GAS stages: take the first letter of each stage Alarm, Resistance, Exhaustion, and you ARE exhausted by the end of it. This is the sort of note to make quickly before you start your essay answer.
Prolonged stress can affect the immune system
Evaluation of the General Adaptation Syndrome
Strengths
GAS was the first theory to explain the physiological effects of stress, influencing many later theories and a lot of research, especially into the negative effects of stress on health
Research into GAS has had positive implications for helping people cope with stress, especially with its contribution to the development of medicines
Limitations
Research fails to consider the effect of psychological processes on how we physically respond to stress, as it could be that those with more resilience respond in a different physiological way
Physiological measurements of cortisol, blood pressure and white cell counts reduce the individual experience of stress to simplistic single-factor biological measurements.
Cortisol and stress
Cortisol is a hormone which is produced in the adrenal cortex through the activation of the hypothalamus-pituitary-adrenal axis (HPA) when subject to a chronic stressor
The immune system comprises mainly white blood cells, which travel through the bloodstream to defend the body against antigens like bacteria, viruses and cancerous cells
Cortisol regulates the body’s immune system to suppress inflammation, which ordinarily is a good thing
However when too much cortisol is in the bloodstream for a long period, then the suppression of the immune system lowers resistance to illness
So stress does not directly cause infections, but with chronic stress the immune system’s ability to fight off antigens is reduced and infection becomes more likely
This reduction in the immune system’s ability to fight off infection when under chronic stress is thought to be why many people get a cold around exam time
The hypothalamus-pituitary-adrenal axis
Research which investigates the General Adaptation Syndrome and cortisol and stress
Kiecolt-Glaser et al (1984) found that stress has a direct effect on the immune system by suppressing natural killer cell activity
Fernald et al. (2008) found that repeated exposure to social stressors like maternal depression and poverty resulted in a reduced (exhausted) cortisol stress response in young children
Both Kiecolt-Glaser et al. (1984) and Fernald et al. (2008) are available as ‘Two Key Studies of Biological Explanations of Stress’’ – just navigate to the next section of the Biological Explanations of Stress topic
You've read 0 of your 10 free revision notes
Unlock more, it's free!
Did this page help you?