Biological Pyschology - Stress

Hypothalmic Piruitary Adrenal Axis

Stress and the immune system

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  • Created by: Aliison
  • Created on: 01-06-10 10:37

Hypothalamic Pituitary Adrenal Axis

Hypothalamic Pituitary Adrenal Axis has two pathways

The pituitary adrenal system [HAPAC]
- The hypothalamus stimulates the pituitary gland
- ACTH is released
- stimulates the Adrenal Cortex to release Corticosteriods into the bloodstream
- The liver releases stored glucose into the bloodstream

The Sympathomedullary system [HANSAM]
The hypothalmus simulates the neutral pathways (nervous system)
- The Adrenal medulla is activated
- Relases Adrenaline and Noradrenaline into the bloodstream

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Stress and the immune system

The immune system is our main defence against infection. It is a complicated network of cells and chemicals throughout the body that functions to seek out and destroy invading particles.

It is well established that psychological stress can adversly affect many aspects of the immune response. These include the ability of white blood cells to perform their function in fighting antigens.

Kiecolt-Glaser (1984) did an experiment to investigate if the stress of examinations effected the functioning of the immune system

- natural experiment, using 75 medical students
- blood samples taken a month before and again during exams
- Immune function was assesed by measuring NK cell activity
- Students were also given questionnaires to asses psychological variables such as live events and loneliness

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Kiecolt-Glaser (1984) continued

- NK cell activity was reduced in the second sample
- NK cell activity was most reduced in participants who also reported to have high levels psychological variables

- Examination stress reduces immune function, leaving the individual vunerable to illness
- Immune function is also affected by psychological variables such as stress of life events. These long term stressors may make individuals more vunerable to the added eddect of short-term stressors such as exams

-This was essentially a correlational study, so a strong conclustion about cause-and-effect relationship can not be drawn - may be other variables
- High in ecological validity, as it was a real exam
- Low in population validity, only used medical students

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