Phisiology

• Stress is defined as an emotional response to a threat that is physical or psychological which causes the body to create an immune response
• Acute stress; causes a short term response EG fight or flight
• Chronic stress; causes a long term response
• General adaption syndrome (Selye 1936) is the body's response to stress
• Stages of General Adaption Syndrome (GAS; Selye 1936); alarm reaction, resistance, exhaustion
• Alarm reaction (General Adaption Syndrome Selye 1936); Immediate response of shock to the stressor causes the body's resources to temporarily decrease before quickly recovering; physiological systems such as the sympathetic nervous system are activated
• Resistance (General Adaption Syndrome Selye 1936); the body attempts to adapt to the stressor but physiological activity uses up large amounts of the body's resources EG fight or flight uses up the body's stress hormones > rest and digest to conserve energy however stress remains and becomes chronic
• Exhaustion (General Adaption Syndrome Selye 1936); adaption begins failing due to the depletion of the body's resources > returning of alarm stage symptoms such as raised heart rate > adrenal glands become damaged and the immune system compromised causing stress related illness of adaption such as coronary heart disease
• Acute response; Sympatho-Medullary Pathway (SAM)/fight or flight

  1. stressor detected by sensory neuron
  2. amygdala sends stress signal to hypothalamus to activate pituitary gland to trigger sympathetic division of autonomic nervous system
  3. sympathetic nervous system triggers adrenal medulla to stimulate the release of adrenaline in the adrenal glands
  4. adrenaline prepares body for fight or flight by increasing (heart rate) and inhibiting (digestion) functions
  5. when the stressor is no longer present/becomes chronic the parasympathetic nervous system triggers rest and digest response
• Hypothalamic-pituitary-adrenal system (HPA)/Chronic

  1. hypothalamus notices a stressor triggering the release of corticotropin releasing factor (CRF)
  2. corticotropin releasing factor is detected by the anterior lobe of the pituitary gland causing the release of adrenocorticotropic hormone (ACTH) into the bloodstream
  3. increasing levels of adrenocorticotropic hormone are detected by the adrenal cortex and triggers the release of cortisol
• Cortisol aids the body's response to stress EG it is a glucocorticoid increasing glucose levels to sustain energy for the stress response
• Cortisol can be damaging within the stress response (Hypothalamic-pituitary-Adrenal system) EG it suppresses the immune system making the body more susceptible to illness
• The hypothalamic-pituitary-adrenal system sustains itself through a negative feedback loop to regulate levels of cortisol; high levels of cortisol trigger a reduction in adrenocorticotropic hormone > reduced level of cortisol
• General Adaption Syndrome (GAS Selye 1936) strength; research support from Selye (1936) subjected rats to physiological stressors such as extreme cold and intense exercise and found the same collection of responses after 6-48 hours regardless of stressor showing all stressors cause the same response HOWEVER this study has ethical and extrapolation issues
• General Adaption Syndrome (GAS Selye 1936) weakness; may overgeneralise stress responses as Mason (1971) created 7 different stressors in monkeys, measuring their urinary cortisol level to measure stress, and found the response was dependent on the stressor EG cold increased cortisol, heat decreased it, and exercise kept it the same HOWEVER this study has extrapolation and ethical issues
• SAM and HPA strength; Can be applied to the real world EG Addison's disease, in which an individual does not produce enough cortisol causing them to be badly impacted by stress causing an Addisonian crisis (EG confusion and increased heart rate), can be helped with hydrocortisone (cortisol replacement therapy)
• SAM and HPA weakness; does not consider psychological responses involved in stress such as cognitive appraisal (Lazarus 1999) which is the subjective interpretation of a stressor; Speisman (1964) found this to be a factor as his participants' reaction to a gruesome surgery depended on if they thought it was consensual or not
• SAM and HPA weakness; gender bias for SAM as Taylor (2000) suggests women adopt a "tend and befriend" response rather than fight or flight showing SAM as androcentric as it may only be generalisable to men