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STRESS 2:Stress and the Immune System
By M. Cardwell, amended by S. McGinnes
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The specification
Stress as a bodily response The body’s response to stress Stress-related illness and the immune system
Stress in everyday life Life changes and daily hassles Workplace stress Personality factors Psychological and biological methods of stress
management
Outline of Today’s Session
The immune system
Effect of stress
Effect of acute stress
Exam
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THE IMMUNE SYSTEM
Defends body against antigens (bacteria, viruses, toxins and parasites)
Cortisol suppresses immune system functioning
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Lymphocyte
A white blood cell generated by the immune system Defends against cancerous cells,
pathogens, and foreign matter Circulates in blood and lymph fluid
Three main types: T cells, B cells (specific immune
responses) Natural killer cells (non-specific)
Cytokines
“Cell signalling molecules” that control response to infection, inflammation, trauma, etc.
Some pro-inflammatory Initiate inflammatory response necessary to recruit
white blood cells to fight disease NB excessive inflammation can be harmful
Others anti-inflammatory Reduce inflammation, promote
healing once injury/infection/foreign body destroyed
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Natural Killer (NK) Cells
Small lymphocytes React against and destroy other cells
without prior sensitisation to them
Part of our first line of defence against cancer cells virus-infected cells
Attaches to target cell, releases chemicals that breach its cell wall, and causes it to lyse (break up)
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Stress and the immune system
Kiecolt-Glaser et al. (1984) natural killer (NK) cells in the blood of students taking exams.
How?
✴ Blood samples taken one month before exams (low stress) and during exams (high stress).
✴ Questionnaires assessed psychological variables e.g. life events.
Findings
✴ NK cell activity was significantly reduced in the second blood sample.
✴ Especially in participants reporting other significant life stressors.
Stress and the immune systemKiecolt-Glaser et al. (1995) compared female caring for relatives suffering from senile dementia with a matched control group.
How
All participants given a wound – a ‘punch biopsy’.
Cytokine levels were monitored.
Findings
Complete wound healing took longer in the carers than the controls.
Cytokine levels were higher.
Carers indicated on a perceived stress scale that they were feeling more stressed.
Acute stress may enhance the immune
system
Evans et al. (1994)
Antibody salivary IgA (sIgA) coats the mucous surfaces of the mouth, lungs and stomach, and helps protect against infection.
How? Arranged for students to give talks to
other students (mild stress).
Findings The students showed increase in sIgA. Whereas levels of sIgA decreased
during examination periods which stretched over several weeks.
• Stress appears to have two effects on the immune system:
• up-regulation for very short-term stress
• down- regulation for long-term stress.
• This fits the SAM/HPA distinction
Sandy and Vandita play for the same netball team. Two weeks ago, while playing in a competition, they both grazed their elbows. Vandita’s wound is healing well, but Sandy’s wound is taking much longer to heal. Sandy is very worried about the plans for her wedding and her forthcoming house move.
Using your knowledge of psychology, explain why Sandy’s wound is taking longer to heal than Vandita’s. (4 marks)
Jan 2010
Exam question
The exam
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What is meant by …. (3 marks)
Describe one research study that has investigated ….. (6 marks).
Describe and evaluate research … (6 marks + 6 marks)
3 studies /explanations3 evaluative
points