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Stress - 1 (The Physiology of Stress (General Adaption Syndrome:
Selye…
Stress - 1
The Physiology of Stress
General Adaption Syndrome:
- Selye suggested after research that when animals are exposed to an unpleasant stimulus they display a universal response, he called this the GAS.
- He found that when rats were exposed to various harmful stimuli the rats developed the same physiological symptoms each time, e.g. stomach ulcers
- The GAS consists of three stages; Alarm, Resistance and Exhaustion (ARE)
- Alarm:
- This stage deals with acute stressors and it is here that the SAM becomes activated.
- When we come across a stressor the fight or flight response is triggered through the ANS.
- Resistance:
- If the stressor is not dealt with then the endocrine system helps to maintain our response, through HPA.
- This a hormonal response and travels through the blood, making it slower.
- Exhaustion:
- This stage occurs when the body can no longer keep up with the stressor, and the bodies resources have become depleted.
- It is caused by severe long-term stress and it is this stage that illness is most likely to occur.
Evaluation:
- Gender Differences: each gender uses different psychological and genetic mechanisms to deal with stress (not universal to both genders). There are also evolutionary differences - men typically fight/flight while women protect offspring
- We can't always run away or fight our stressors-fight or flight less adaptive today
- The transactional model of stress: Developed by Lazerus & Folkman, this model emphasises that an individuals cognitive assessment effects how they perceive, and react, to stressors
The Sympatho-Medullary Pathway (SAM System):
- The short term response to stress
- A signal is sent down the sympathetic branch of the ANS which stimulates our Adrenal Medulla
- The signal is sent via our CNS to the two endocrine glands located just above the kidneys.
- The middle part of the adrenal gland, the Adrenal Medulla responds by releasing Adrenaline and small amounts of Noradrenaline into our blood streams
- Adrenaline & Noradrenaline circulate through our bodies and affect the key organs, such as the heart, and the muscles.
- This is known as the fight or flight response, which will be reduced after a few minutes and the body will be back to normal.
The Pituitary-Adrenal System (HPAC): - The response to chronic stressors
- The hypothalamus is stimulated when the brain notices a stressor
- A signal is then sent to the pituitary gland in the brain which releases a hormone called ACTH
- ACTH travels through the bloodstream down to the Adrenal Cortex, the outside of the adrenal gland, which responds by releasing corticosteroids, such as cortisol, into the blood stream.
- Corticosteroids are a vital part of the stress response as they have two main effects on the body:
- they release glucose from the liver to be used as energy by the muscles
- they suppress the immune system to redirect energy to other areas, e.g. the brain & muscles. This is called immunosuppression
Sources of Stress
Life Changes:
- Holmes & Rahe developed the Social Readjustment Rating Scale to measure life changes. It consisted of 43 life events, an individual identifies which items occurred within a specific time period. Each event has a score in terms of Life Change Units (LCU).
- Rahe et al investigated the sources of life changes as a source of stress. They found a positive correlation of +.118 between the LCU and illness. As some positive life changes were on the SRRS scale it suggests that it is change, rather than negative change, that is important in creating stress.
- This is supported by Cohen who found participants with a higher stress score were more likely to get ill.
- Evaluation:
- Correlational - cannot prove cause & effect
- Individual differences
- Self-report: Social Desirability Bias
Daily Hassles:
- Kanner et al created a Hassles and Uplift Scale (HSUP) which consists of 117 items.
- The negative effects of daily hassles can be balanced out to an extent by the positive experiences of Daily Uplifts.
- Accumulation: a build up of stress from daily hassles can result in more serious stress reactions such as anxiety & depression.
- Amplification: An alternative explanation is that chronic stress due to major life changes may make people more vulnerable to daily hassles.
- Kanner et al investigated whether daily hassles or life changes were the most stressful.They found that the HSUP scale tended to be a more accurate predictor of stress related problems than the SRRS. Uplifts had a positive effect on the stress levels of women but not men.
- Evaluation:
- Individual differences
- +Ruffin: daily hassles more important than life events
- Reliability of recall
- Self-report: Social Desirability Bias
Workplace Stress:
- Two causes of workplace stress:
- Lack of Control: Many peoples workload and pattern of work is determined by someone else
- Work Overload: Having too little or too much to do, not having enough time to do it in etc.
- These two factors have now been combined to form the job-strain model suggesting the two factors create stress & illness.
- Marmot et al: Lack of Control Whitehall I and Whitehall II
- Whithall I showed in a questionnaire that those workers with lower pay grade had twice the illness rate of workers in the higher pay grade
- Whithall II found in a longitudinal study over 5 years that those with lower pay grades were 1.5 X more likely to show signs of heart problems than those in the highest pay grade.
- Evaluation:
- Individual differences - Lazerus - transactional approach - perceive stressors in different ways
- Self Report
- Johanson et al: Work Overload
- Studied high risk workers (high workload - low control) compared to low risk workers (low workload - high control) and recorded their daily levels of adrenaline and noradrenaline.
- They found the high risk group had higher illness rates and levels of adrenaline than the low risk.
Measuring Stress
Social Readjustment Scale: SRRS
- +Popular
- +Successful & gives opportunities to research stress
- Individual Differences
- Only looked at adults
Physiological Measures: Blood pressure/cortisol levels etc
- +Avoids problems with self-report
- Non-specific response - physical responses happen with any kind of emotion (Correlational)
Hassles and Uplift Scale: HSUP
- +Popular
- Time consuming
- Self-report
Skin Conductance Response:
- Measures electrical conductivity of skin - related to arousal of SNS - immediate stress - electrodes placed on fingers & small voltage applied.
- +Practical applications - e.g. lie detectors
- +Avoids problems with self-report
- Non-specific response
-