- Year 2 stress
- All material is covered in these notes
- AO1 in an extensive amount with A03
- Evaluations are all in PEEL format
- All possible 16 markers are covered
The physiology of stress
- Physiology is the study of processes in living organisms that are essential for survive
- There are two main processes in stress that are important for survival
- This includes the general adaptation syndrome and the physiological stress response
- General adaptation syndrome (GAS) is an explanation of how the body responds the same way to any
stressor overtime. The response goes through three stages: alarm reaction, resistance and exhaustion
- Selye (1936) believed ‘stress’ was the body’s attempt to adapt to a stressor
- Stressor is anything that causes the body stress
- Acute stressor is a brief / sudden source of stress
- GAS can protect the body in a short term response via the alarm reaction and resistance
- Chronic stressor is a long lasting / persistent source of stress
- GAS can damage the body in long term response via exhaustion
- Alarm reaction is when the stressor is first acknowledged and the body is in ‘shock’
- This causes the body’s resources to decrease before quickly recovering
- Physiological systems such as the sympathetic nervous system are activated for flight or fight
- Resistance is the body’s attempt to not give in to the stressor
- Increasing physiological activity (energy required) - the SNS remain active
- The person may appear to be coping but resources are being consumed at a harmful rate
- When the body’s attempt to adapt to the chronic stressor is failing it enters the exhaustion stage
- The parasympathetic nervous system is activated to conserve energy for the long term
- Resistance decreases (starts to give in to the stressor)
- At this stage they can re-experience symptoms of sympathetic arousal that occurred in the alarm stage
- For instance sweating, raised heart rate and high blood pressure
- Over time the adrenal glands may becomes destroyed and immune system compromised
- P: One strength for GAS is it is based on Selye (1936) research.
- E: Rats were exposed to different physical stressors such as extreme cold, excessive muscular exercise and
surgical injury. The rats' responses were tracked throughout the resistance and exhaustion stage.
- E: He found that all the rats had a similar collection of responses.
- L: This demonstrates that there is a general response regardless of the stressor.
- P: On the other hand it may be inappropriate to generalise the findings from Selye to humans.
- E: Mason (1971) replicated Selye's procedures using monkeys instead. He measured the response to
several different stressors by measuring levels of urinary cortisol. He found that outcomes depended on
the stressor (In extreme cold cortisol levels increased and in extreme heat cortisol levels decreased)
- E: Given that monkeys are more commonly related to humans than rats Mason’s research may offer a
more accurate reflection of how humans can respond to stress.
- L: Overall this conflicting research indicates the limitations of GAS in explaining human responses to stress.
- Physiological stress response (stress responses for acute and chronic stress)
- The body communicates through two different systems - endocrine system and the nervous system
- The nervous system is divided into the central nervous system and the peripheral nervous system
- The peripheral system is divided into the autonomic nervous system and somatic nervous system
- The autonomic nervous system (ANS) can be divided into the parasympathetic state (normal resting state)
and the sympathetic state (physiologically aroused)
- Sympathomedullary pathway (SAM) controls how the body responds to an acute stressor
- The SMA can also be known as the flight or fight response
,- When an acute stress is processed the hypothalamus activates the sympathetic branch of the ANS
- The sympathetic nerves connect the brain to the heart and the adrenal gland
- Sympathetic arousal stimulates the adrenal medulla to release adrenaline and noradrenaline
- This causes the heart to beat faster, muscles to tense and glycogen to convert to glucose
- This glucose is then used to fuel the fight or flight response
- This response can end when the the stressor is no longer present
- This means the parasympathetic nervous system has taken over
- Its main priority is to conserve energy (rest and digest response)
- Overtime the stress can go from being acute to being chronic
- Hypothalamic pituitary adrenal system (HPA) controls how the body responds to a chronic stressor
- The HPA takes longer than SMA to activate but its effects can persist for longer periods
- A stressor is processed by the hypothalamus
- This causes the sympathetic nervous system to be activated
- The hormone corticotropin releasing factor (CRF) is also produced
- The CRF is detected by the the pituitary gland causing the release of ACTH
- ACTH is adrenocorticotropic hormone and is released into the bloodstream
- ACTH levels are detected by the adrenal cortex and the hormone cortisol is secreted
- Cortisol helps the body to cope with stressors by controlling how the body uses energy. It suppresses
immune system activity.
- This process then repeats via a negative feedback loop
- The hypothalamus and pituitary gland monitor cortisol levels in the blood
- If there are high levels of cortisol there is a reduction of CRF and ACTH
- This would then cause cortisol levels to reduce
- P: One strength is that research into the physiology of stress has had practical value.
- E: For example, Addison's disease is a rare disorder of the adrenal glands cortisol does not get produced.
The lack of cortisol can trigger abnormal heart rhythms and drop in blood pressure with stressors.
- E: This knowledge has led to treatment to be developed for these individuals (They can administer daily
cortisol replacements)
- L: Therefore understanding stress physiology has improved the standard of living for some people.
- P: One limitation is that physiological explanations ignore psychological factors in stress.
- E: Speisman et al. (1964) asked students to watch a gruesome medical procedure on film while their heart
rates were measured. Changes to heart rate depended on how the students interpreted what was
happening in the film.
- E: If they believed the procedure to be traumatic their heart rates increased. However when they were
informed the procedure was part of a voluntary and joyful rite of passage their heart rates decreased.
- L: This finding cannot be explained solely by a physiological theory.
The role of stress in illness
- Immunosuppression is when stress can cause illness by preventing the immune system from working
efficiently and carrying out its usual task of identifying and destroying pathogens
- For example cortisol inhibits the production of lymphocytes
- Kiecolt-Glaser investigated the effects of two different stressors
- Procedure: Kiecolt-Glaser (1984) investigated the effects of exams on 75 medical students
- Blood samples were taken twice - before their exam (low stress) and the day of their exams (high stress)
- They completed a questionnaire measuring the different sources of stress and reported any psychological
symptoms they had experienced
,- Findings: Activities of NK and T Killer cells decreased in the second sample compared to the first sample
- This decrease was most significant in students who reported themselves feeling lonely and had other
stress related problems in their lives
- Procedure: Kiecolt-Glaser (1991) carried out a longitudinal study comparing the health of two groups
- Caregivers looking after their relative with Alzheimer's and a matched group of non caregivers
- Findings: Over 13 months caregivers showed a weaker immune system whereas the control group
showed no change. The caregivers had illnesses on significantly more days and higher levels of depression
(32%) compared to the control groups (6%)
- P: One strength is that research into stress and illness has many real-world benefits.
- E: Dharbhar's research into acute stressors lead to patients being given low doses of stress hormones
before surgery. This would stimulate their immune systems and improve their chances of making a full
and fast recovery afterwards.
- E: Other research shows students who took a relaxation training programme had a better immune system
during an exam period compared to those who did not participate (Kiecolt-Glaser 1992)
- L: This show the numerous benefits research into stress and illness have had for different people.
- P: One limitation is that there is conflicting research.
- E: Dharbhar (2008) subjected rats to mild acute stressors and found that immune cells (lymphocytes)
flooded into the bloodstream and body tissues in preparation for physical damage.
- E: This showed that acute stressors didn’t have the same immunosuppressive effects as chronic stressors.
- L: This suggests that the relationship between stress and the immune system is complex and we can’t
conclude that all stressors lead to immunosuppression.
- Cardiovascular disorders are any disorder of the heart or blood vessels which affect the brain
- Stress may contribute to CVD’s such as heart diseases and strokes
- Adrenaline causes an increase in heart rate which can affect muscles directly
- Wilbert-Lampen (2008) researched the effects that acute stress had on CVD’s
- Procedure: They looked at incidents that caused heart attacks in German footballers during matches they
played in 1996 world cup
- Findings: When they played cardiac emergencies increased by 2.66 times compared to a control period.
This study showed that acute stress doubled the risk of experiencing a CVD
- Yusuf et al (2004) researched the effects of chronic stress in a INTERHEART study
- Procedure: This involved 52 studies aiming to identify major risk factors in CVD’s across different cultures
- They examined 15000 people who had suffered a heart attack with a similar number of those who had not
- Findings: several chronic stressors were found to be linked to heart attacks including workplace stress and
other stressful life events
- Stress contributed to heart attacks more than obesity
- Stress caused the development of CVD but it also made existing disorders worse
- P: One limitation is that the effects of stress on CVDs are mostly indirect.
- E: Orth-Gomer et al. (2000) found that marital stress tripled the risk of a heart attack in women who
already had CVD.
- E: This is a different situation from demonstrating that stress causes CVDs to develop in the first place.
- L: This suggests that stress increases a person's vulnerability to developing CVDs and does not cause it.
- P: One strength is research to support the link between stress and CVDs.
- E: Song et al. (2019) identified 130,000 people with stress-related disorders. Other participants were
unaffected siblings and had no stress-related disorders.
- E: Compared with controls, people with stress-related disorders had a 64% greater risk of a CVD.
- L: This shows that exposure to chronic psychological stress can significantly increase CVD risk.
, Sources of stress: Life changes
- Sources of stress are any feature of the environment that causes stress, including factors associated with
work, everyday minor hassles and major changes in our lives.
- Life changes are significant and relatively infrequent events in people's lives that cause stress. They are
stressful because we have to expend psychological energy coping with changed circumstances.
- The bigger the change the greater the adjustment will be and the associated stress
- The effects of life changes also accumulate - this can create more stress and makes it harder to adapt
- Life changes are believed to be the cause of illness
- Holmes and Rahe’s (1967) social readjustment rating scale measures life changes in LCU
- LCU stands for life changing units (measures life changes from most to least stressful)
- Higher the LCU value the more adjustment is believed to be needed ie more stressful
- Those who completed the list were to tick anything they had experienced in past 12 months
- The total score would be added and then correlated to the participants health
- This was to see if there was any relationship between stress and health
- Rahe et al (1970) then concluded that a score below 150 LCU means reasonable health
- It was found that those who scored higher than 150 LCU did develop illness the following year
- Rahe et al. (1970) concluded that life changes could predict later illness based on correlation to an extent
- Procedure: They focused on individuals who were apart of the US Navy
- Before their employment the participants reported life changes from the past six months using a scale
- An LCU was calculated for each person. They reported their illness during their time of employment
- This was done without any of the participants and medical staff knowing the purpose of the study
- A researcher reviewed medical records calculating an illness score for everyone after their employment
- Findings: Results showed a significant positive link between participants LCU scores and their illness
scores - those experiencing more stressful life changes before employment tended to have more illnesses
Evaluation:
- P: One limitation is that life changes do not affect everyone in the same ways.
- E: Byrne and Whyte (1980) tried to predict who would experience a heart attack based on SRRS scores.
- E: The researchers found that they could only make accurate predictions if they considered how each
person personally felt about the life change ie may have a high LCU score due to divorce which could show
them to be stressed but they might actually be happy with the outcome.
- L: Therefore the life changes approach lacks validity because it does not consider individual differences in
how life changes are perceived.
- P: A further weakness of research into life changes determining stress is it lacks validity.
- E: DeLongis et al (1988) gave participants questionnaires on life events and daily hassles. They found no
relationship between life events and health but found a significant positive correlation between daily
hassles and stress.
- E: An explanation for this is major life changes are relatively rare and infrequent and as a result can’t
explain why there are many stress related illnesses eg an individual is not going to get divorced everyday
- L: This suggests that daily hassles are a more valid indicator of stress related illness.
- P: A strength of research into life changes are the practical applications.
- E: For example, the SRSS has provided many insights into suicide.
- E: Heikkinen & Lonnqvist (1995) found that living alone was not a common factors that caused suicide in
later life but rather the physical illness they had experienced.
- L: This research has led to targeted support interventions for vulnerable people such as care and
counselling for elderly people with physical illness
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