Stress - Stress and the immune system Flashcards
What is the immune system?
- A system of cells that fights ‘intruders’ to the body.
- It protects us from bacteria, parasites and toxins that would make us ill if not for the immune system
- It contains white blood cells (leukocytes) which identify and eliminate all foreign bodies (antigens).
How does the immune system operate in 3 simple steps?
- Creates a BARIRER that prevents antigens entering our body (eg. wound healing)
- If the antigen does get it the immune system DETECTS and ELIMINATES it before it can reproduce.
- If it does reproduce and starts causing us problems the immune system is responsible for ELIMINATING it.
BARRIER, DETECT, ELIMINATE
Name 5 parts of the immune system and their major roles.
SPLEEN - production of blood cells and the filtering of blood (trapping micro-organisms)
WHITE BLOOD CELLS - responsible for the detection and elimination of antigens. There are many types.
BONE MARROW - production of blood cells
LYMPH NODES AND VESSELS - involved in storage, transportation of lymph (water) and filtering of antigens.
THYMUS - Production of T-cells
TONSILS - part of the system which creates a barrier and eliminates antigens entering our digestive system.
How are Stress and the Immune System linked?
- The nervous system sends nerves directly into tissue that form and store cells.
- These cells can be affected negatively by cortisol in the nervous system, produced when under stress.
- Therefore stress directly affects the immune system and can create dysfunction and illness.
The immune system can become both under vigilant and over vigilant under stress. What does this mean?
Under vigilant - the immune system is depressed and not doing enough to combat antigens and therefore we become ill due to the antigens
Over vigilant - the immune system is working too hard and is becoming the cause of the illness
What is immunosuppression?
A ‘slowing down’ of the immune system where it becomes less affective and efficient. This leaves us more susceptible to infection.
FEMALE CARERS – Kiecolt-Glaser et al (1995) investigated direct effects of stress on the immune system in a real life situation with female carers - specifically looking at how quickly wounds heal? What were their procedures?
- 13 (plus 13) female participants who were carers for relatives with dementia. As they were carers they were likely to suffer from ‘chronic stress’
- they were ‘matched’ against 13 other women who were ‘low stress’
- Levels of cytokine (a protein linked to effective immune system) were measured and participants answered a stress perception questionnaire
- A wound was inflicted on the 26 participants (3.5mm puncture biopsy
- Healing time was measured
FEMALE CARERS – Kiecolt-Glaser et al (1995) investigated direct effects of stress on the immune system in a real life situation with female carers - what did they find?
- wounds healed quicker in the low stress group and took longer to heal in the ‘carers’
- Cytokine levels were lower in carers (suggesting low functioning of the immune system)
- Carers perceived (via questionnaire) higher stress in their lives.
FEMALE CARERS – Kiecolt-Glaser et al (1995) investigated direct effects of stress on the immune system in a real life situation with female carers - what were their conclusions?
Their findings support the idea that Chronic Stress depresses the immune system and negatively affects its functioning. This would lead to increased vulnerability to infection.
FEMALE CARERS – Kiecolt-Glaser et al (1995) investigated direct effects of stress on the immune system in a real life situation with female carers - what were the strengths of the study?
- Ecological validity as these were real people with real stress in their lives
- Matched participant design isolated stress and the differing variable
- Supported my Marucha et al (1998) in the study of students immune system in exam periods using punch biopsy in the mouth
- Field experiment that gathered natural behaviour
- Findings could be generalised beyond the research setting as they investigated ‘real life’ stress.
FEMALE CARERS – Kiecolt-Glaser et al (1995) investigated direct effects of stress on the immune system in a real life situation with female carers - what were some of the potential weaknesses of the study?
- The study was correlational so only ‘suggests’ relationship between two variable (stress and immune system) rather than proves it
- The volunteer sample size was small
- As they were volunteers they may be ‘type A’ personalities (who will put themselves forward) who are prone to increased stress levels
- Low population validity as gynocentric (focussed only on women)
MEDICAL STUDENTS – Kiecolt-Glaser et al (1984) investigated the impact of stress on the immune system of medical students. How? What did they do?
- Assessed NK Cell Activity (High levels indicate high immune system functionality)
- Took blood samples 1 month before exams ( a low stress time)
- Then took another blood sample during the exam period
- Plus a stress questionnaire to investigate other life stressors
MEDICAL STUDENTS – Kiecolt-Glaser et al (1984) investigated the impact of stress on the immune system of medical students. What did they find and what were the conclusions of the study?
F - The exam period produced lower KN Cell activity in the blood (i.e. lower immune system functioning)
F - they also found that the loneliest students had lowest NK cell activity
C - The immune system appears to be affected by the level of environmental stress
March et al 1998 (DENTAL students) - supported the work of Kiecolt-Glaser - Can you summarise the study ?
Aims - To investigate the relationship between stress and the immune system
Procedures - 11 dental students were given a punch biopsy in the hard palate of the mouth on 2 occasions
- In the summer holidays
- 3 days before an exam
Findings - It took 40% longer to heal when the wound was inflicted just before an exam
Conclusion - the immune system is suppressed and works more slowly under stressful situations and slows recovery from illness
What are the difficulties in trying to link or stress and illness proposed by Lazarus (1992)
- Health is affected by many factors making it very difficult to isolate stress as the only impact variable
- Health stays generally stable over time and therefore immediate change is difficult to see
- The cost of continuous monitoring of participants health would be very expensive and impractical
