General Adaptation Syndrome (GAS) - Theory of Stress

Introduction

• Hans Selye (1907- 1982) was a Hungarian endocrinologist, first to give a scientific explanation for biological stress.
  
• Hans Selye explained his stress model based on physiology and psychobiology as General Adaptation Syndrome (GAS).
  
• His model states that an event that threatens an organism’s well-being (a stressor) leads to a three-stage bodily response:
  
  • Stage 1: Alarm
    
  • Stage 2: Resistance
    
  • Stage 3: Exhaustion
    
• He explained about hypothalamic-pituitary-adrenal axis (HPA axis) system which prepares the body to cope with stress.
  
• Selye also explained about a local adaptation syndrome which refers to the inflammatory response and repair processes occur at the local site of tissue injury as in small, topical injuries, such as contact dermatitis which may lead to GAS if the local injury is severe enough.

Stages

• Stage 1: Alarm
  
  • Upon encountering a stressor, body reacts with “fight-or-flight” response and sympathetic nervous system is activated.
  • Hormones such as cortisol and adrenalin released into the bloodstream to meet the threat or danger.
  • The body’s resources now mobilized.
• Stage 2: Resistance
  
  • Parasympathetic nervous system returns many physiological functions to normal levels while body focuses resources against the stressor.
    
  • Blood glucose levels remain high, cortisol and adrenalin continue to circulate at elevated levels, but outward appearance of organism seems normal.
    
  • Increase HR, BP, breathing
    
  • Body remains on red alert.
    
• Stage 3: Exhaustion
  
  • If stressor continues beyond body’s capacity, organism exhausts resources and becomes susceptible to disease and death.
    

Terminology

• Stress: is a condition in which the human system responds to changes in its normal balanced state.
  
• Stressor: is any thing that is perceived as challenging, threatening or demanding.
  
• Eustress or positive stress: Manageable stress which can lead to growth and enhanced competence.
  
• Distress or Negative stress: Uncontrollable, prolonged, or overwhelming stress is destructive.
  
• Adaptation: is the change that takes place as a result of the response to a stressor.
  
• Coping: a balancing act between biological, psychological, and social process.
  
  • Adaptive Coping Contribute to resolution of the stress response
    
  • Maladaptive Coping –Strategies that cause further problems
    
  • Active Coping – Actively seeking resolution to the stress  
    
• Homeostasis: refers to a steady state within the body and various physiologic mechanisms within the body respond to internal changes to maintain a relative constancy in the internal environment.
  
• Resilience: Resistant quality that permits a person to recovery quickly and thrive in spite of adversity
  

Conclusion

• Hans Selye's theory profoundly influenced the scientific study of stress.
  
• Stress is a state produced by a change in the environment and the nature of the stressor is variable.
  
• The individual appraises and copes with the stress, to reach the goal of adaptation.
  
• The process is called coping with the stress, and it is achieved through a compensatory process with physiologic and psychological components.
  

References

1. Selye H. The Stress of Life (rev. edn.). New York: McGraw-Hill, 1976.
   
2. Selye H. Stress in health and disease. Reading, MA: Butterworth, 1976.
   
3. Smeltzer SC, & Bare BG. [Edrs] . Brunner and Suddarth's Textbook of Medical-Surgical Nursing. 10th edition. Philadelphia: Lippincott Williams & Wilkins, 2004.