Stress in everyday life & immune system

Is the biological response to a demand that threatens an organism.
The sympathetic branch of the autonomic nervous system is activated ready for the 'fight or flight' response.
1. If the stressor 'stands down' at any time during the physiological response, the parasympathetic nervous system is employed to return the body to its normal homeostatic state.
The General Adaptation Syndrome (GAS)
1. 1. ALARM - Activation of pituitary-adrenal and sympathomedullary system. Heart rate increases breathing and energy levels increase preparing for 'fight or flight'.
  1. 2. RESISTANCE STAGE - Body changes and adapts to continued stressor. Body appears to return to normal, but arousal levels are still high. Body, under continued stress, starts to run out of resources (e.g. long-term use of hormones).
    1. 3. EXHAUSTION - If stress continues, body's resources deplete and it can no longer cope with the stress. Immune system loses efficiency and illness may result. In Selye's studies, many animals died.
2. Strengths - The model has resulted in a better understanding of the physiological effects of stress. It is useful in the prediction of the physiological response to stress. It can be applied to other areas, such as the link between athletes suffereing from injury/stress and recovery time. There has been a raised awareness of the stress in animals kept in captivity, with the introduction of animal enrichment programmes.
3. Limitations - The results may not be applicable to humans because animal physiology may be different. We are not aware of animals' perception of stress. The research was ethically improper as the animals suffered.
Stress-related Illness And The Immune System
1. Coronary Heart Disease and Stress
  1. Based on research by Rosengren et al. (1991)
    1. Higher blood pressure is a response to stress and damage could result.
    2. Long-term stress may mean permanently constricted blood vessels in the heart.
    3. Stress hormones increase fatty deposits on the artery walls.
2. Stress and The Immune System
  1. The white cells are the first barrier.
  2. T-cells in turn attack anything that carries disease and produce B-cells to destroy the carrier cells.
  3. Stress can cause the immune system to be suppressed, leaving the body vulnerable to illness.
  4. Key Study : Kiecolt-Glaser et al. 1984
    1. Aim: To see if the immune system is affected by external stressors.
    2. Procedure: Students gave a blood sample a month before the exams (low stress time) and again during the exam period (high stress time). The samples were tested for T-cell content. Students also filled out a questionnaire about loneliness and lifestyle factors.
    3. Findings: During the exam period it was found that the students had fewer killer cells to deal with incoming disease.
    4. Conclusion: Stress is a key factor in the lowering of the immune system.
    5. Pros - As a natural experiment, it has high ecological validity - the exams were real-life experiences. It was a correlational study, so cause and effect could not be ascertained. Cons - Those who suffered more stress seemed to have other external stressors such as loneliness.
Life Changes and Daily Hassles
1. Key study: A study of life changes using the Social Readjustment Rating Scale (Holmes and Rahe 1967)
  1. Aim: To develop a rating scale to quantify the amount of stress in people's lives that will produce illness.
  2. Procedure: Participants were asked to tick the events that they had experienced over a past period of two years. Many people were asked to rate life events in terms of the amount of readjustment they would have to make to the psychological impact of those events. The highest rated was the death of a spouse, and was given an arbitary value of 100 (life change units); redundancy came out at 47. The scores were then totalled.
  3. Findings: The higher the score of the participant, the higher the odds of that participant developing stress-related illness.
  4. Conclusion: Stress can be objectively measured and there is a positive relationship between the number and level of life changes and the risk of developing illness.
  5. Criticisms: Pros - The scale has been used in over 1000 studies, showing a positive relationship between scores and physical illness. The rating scale did show that positive events can cause stress as well as negative ones, but it did not differentiate between the two and assumed that any life change was stressful (pro & con). This was the first time that levels of stress in people's lives had been quantified. The study confirmed that life events could lead to health breakdown. Cons - It showed a correlational relationship between life events and ill health, but casuality cannot be assumed. Self-reporting is not reliable. The study did not take into account individual differences - we may percieve life events differently (some may find divorce stressful while others are relieved). It assumed adult experiences and cannot be applied to adolescents.
2. Key Study: The naval study (Rahe et al. 1970)
  1. Aim: To see if stress and illness are related to each other.
  2. Procedure: US male naval personnel who were away from home on a tour of duty for six months were asked to complete the Social readjustment Rating Scale. They were then monitored over the six months in order to see if illness developed.
  3. Findings: They found that higher totals of life change unit scores correlated with increased illness.
  4. Conclusion: A relationship between illness and life changes can be assumed.
  5. Criticisms: Pros - The study showed some support for life changes prior to duty affecting health. Cons - The correlation was very weak and, in other circumstances, there may be no correlation. All the participants were male and sailors, making it difficult to generalise from the findings.

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Stress in everyday life & immune system

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	Created by lauren.woiwod over 10 years ago