Stress
1. Outline the pituitary-adrenal system.
It is activated under conditions of chronic stress. The hypothalamus communicates with the pituitary
gland causing it to release ACTH which is detected in the bloodstream by the adrenal cortex which then
releases corticosteroids such as cortisol. The corticosteroids have a range of effects on the body including
causing the liver to release glucose stored in the body raising blood glucose and fatty acid levels and a
suppression in immune functioning.
2. Outline the sympathomedullary pathway.
It is activated as a response to acute stressors. The hypothalamus activates the sympathetic nervous
system and so autonomic centres stimulate the adrenal medulla to release the hormones adrenaline and
noradrenaline. This gets the body ready for fight or flight which raises heart rate, blood pressure and
breathing rate. Unimportant processes such as digestion are slowed.
A study by Taylor found that the activation of this pathway was different in men and women as
women have higher levels of Oxytocin which promotes relaxation and so helps them recover quicker
from acute stress.
3. Outline and evaluate studies into the impact of stress on the immune
system.
Cohen et al investigated general life stress and the impact it had on vulnerability to the common
cold. Participants rated how stressed they were to give an overall stress score. They were then exposed
to the cold virus and 82% became infected showing that the higher stress ratings were correlated with
the chance of developing a cold and thus they had a lower immune functioning. The problem with this
study is the ethical issues of exposing to a virus, lacking internal validity as required participants to recall
stressful events and therefore relied on memory, they did not actually measure immune functioning and
there is no causal relationship.
A study by kiecolt-glaser et al used medical students who were about to take their final exam. They
took blood samples one month before the exam to measure the amount of natural killer cells and then
another sample during the exam period. They also completed questionnaires about negative experiences
and social isolation. They found that natural killer cells, and hence immune functioning, were lower in the
high stress examination period samples and the greatest reduction in killer cells was in those
experiencing high levels of social isolation. With this study they did directly measure immune functioning
however they did not assess actual illness outcomes, they only used medical students so it cannot be
generalised and natural killer cells are only one component of the immune system.
, Dollard and Miller carried out a meta-analysis and found that a reduction in immune functioning is liked
with chronic stressors and acute stressors may actually increase immune functioning.
It has also been found that hormones released in the pituitary adrenal system reduce t-lymphocytes and
shrinks the thymus gland which directly suppresses the immune system.
4. Describe research studies that has investigated stress in the workplace.
Stress from the workplace can include the environment, the home-work interface, the control and
the demand of work.
Marmot et al wanted to investigate the link between workplace stress and illness; he argued that
jobs with high demand and low control created the most stress (job strain model). He used civil servants.
They answered questionnaires and observations to measure their job control and demand and were
checked for signs of cardiovascular disease. Participants were reassessed five years later, and throughout
the five years records of stress related illnesses were kept. They found that those who were 'higher up' in
the profession and so had high job control had the fewest heart problems and those with low control
were 3 times more likely to die of heart attacks. This study concluded that low control is associated with
higher levels of stress and therefore stress related illnesses. The problem, however is that they found
little to support the claim that high demand was associated with stress. To evaluate, the study is largely
based on self-reports so could be biased, lower grade jobs could include people who smoke more with is
a factor of CHD, and they used a biased sample.
Marmots study is supported by fox and also by johansson who studied Swedish sawmill workers
whose job required a lot of repetitiveness and a high workload. This led him to conclude that jobs like this
increased the risk of stress related illness.
5. Outline and evaluate evidence which suggests that personality can
affect our experience of stress.
Type A personalities are associated with being time pressured (work to deadlines, multitasking...),
competitive and hostile (easily irritated and directs anger inwards) these personality traits make people
with type A behaviour more vulnerable to stress. Friedman and rosenman interviewed middle aged men
and categorised them as either type A or type B (opposite behaviour to type A) using structured
interviews and observations. After following up for 8 1/2 years 257 men had had heart attacks and 69% of
them had type A personalities and it was found that there was double the chance of CHD in type A than
in type B showing that TAB is correlated with heart disease. This study lacked population validity and it
was gender biased, there was no causal relationship and a study by Shekelle found that in fact there was
no difference in the amount of CHD in type A or type B.
Another personality type that shows how personality effects out experience of stress is the hardy
personality. The main traits include a sense of control over one’s life including stressors, commitment and
involvement in life and viewing life and stressors as a challenge. Kobasa carried out questionnaires on
business executives using the SRRS and the hardiness test to find that having a hardy personality lowered
arousal to stressors and so the stress response wasn't activated as often and there was a reduction in
stress related illnesses.
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