The general adaptation syndrome as a response to stress

The general adaptation syndrome (GAS) outlines the body's physiological reaction to stressors, based on research into hormonal responses. This model highlights how prolonged exposure to stress can lead to physical health issues.

Stages of the general adaptation syndrome

Hans Selye (1936) proposed the GAS as a three-stage process that occurs regardless of the stressor's nature:

• Alarm stage - The body detects a stressor and activates a heightened state of alertness, preparing for immediate action through mechanisms like the fight-or-flight response.
• Resistance stage - If the stressor persists, the body attempts to adapt by sustaining elevated arousal levels, though resources begin to deplete.
• Exhaustion stage - With ongoing stress, the body's ability to resist breaks down, leading to a return of initial alarm symptoms and the onset of health problems such as elevated blood pressure, digestive ulcers, or mental health issues like depression.

Evaluation of the general adaptation syndrome

• The model assumes a uniform response to all stressors, overlooking differences in how individuals react based on personal factors.
• Research has linked ulcers more directly to bacterial infections, but stress can exacerbate vulnerability by compromising immune defences.
• Selye's early experiments on animals, such as injecting rats with hormones, demonstrated stress-related illnesses, but these findings may not fully translate to human experiences.

How stress affects the cardiovascular system

Prolonged stress triggers ongoing physiological changes that strain the heart and blood vessels, potentially leading to serious disorders. This occurs as stress hormones elevate heart rate and constrict blood flow, increasing overall pressure within the system.

Cardiovascular disorders linked to stress

Chronic stress contributes to several conditions by promoting sustained high blood pressure and vessel damage:

• Arteriosclerosis - Thickening and hardening of artery walls, reducing flexibility and blood flow.
• Coronary heart disease - Narrowing of arteries supplying the heart, limiting oxygen delivery.
• Thrombosis - Formation of clots that can block blood vessels.
• Heart attacks and strokes - Sudden blockages causing tissue death in the heart or brain, resulting in functional impairments.

These issues arise because long-term stress maintains an elevated state that the cardiovascular system cannot sustain without harm.

Research into stress and heart function

Studies have explored how acute stress influences heart performance, revealing direct links between stress responses and cardiovascular risks.

Krantz et al (1991) — Stress and the heart

• Method - A controlled lab experiment involved 42 participants completing demanding tasks, including mathematical problems, concentration exercises, and speaking publicly, while monitoring blood pressure and signs of reduced heart blood flow (myocardial ischaemia).
• Results - Those displaying the most significant reductions in heart blood flow also experienced the largest rises in blood pressure during the tasks.
• Conclusion - Stress appears to have a direct effect on bodily processes, heightening the risk of heart-related conditions.
• Evaluation:
  • The study shows associations during stress but does not establish clear cause-and-effect.
  • Participant variations influenced outcomes.
  • Lab settings reduce real-world applicability.
  • Supporting evidence from Williams (2000) indicates that stronger anger responses correlate with greater heart disease risks.

The impact of stress on the immune system

The immune system protects the body by using specialised cells and substances to combat invaders like bacteria and viruses. However, extended stress disrupts this defence mechanism, leading to greater susceptibility to health problems.

Effects of chronic stress on immunity

• Persistent stress causes immunosuppression, where the system's efficiency drops, making infections and diseases more common.
• This occurs because stress hormones interfere with the production and activity of protective white blood cells.
• Evidence from various investigations confirms that ongoing stress heightens the likelihood of catching illnesses, as the body struggles to mount an effective response.

Studies on stress, ulcers, and wound healing

Research using animal and human participants has demonstrated how stress contributes to specific physical ailments, including digestive issues and delayed recovery from injuries.

Brady et al (1958) — Stress and the development of ulcers

• Method - Pairs of monkeys were subjected to electric shocks; one in each pair (the "executive" monkey) could delay shocks by pressing a lever, while the other had no control.
• Results - The executive monkeys developed ulcers at a higher rate and were more prone to fatal outcomes.
• Conclusion - The stress of attempting to manage the situation weakened immune responses, promoting ulcer formation.
• Evaluation:
  • Ethical concerns arise from the harm inflicted on animals.
  • Applicability to humans is limited due to species differences.
  • Parallels exist in human scenarios, such as high-stress roles with low control, like junior jobs or periods of joblessness.

Kiecolt-Glaser et al (1995) — Stress and wound healing

• Method - An independent groups design compared 15 women providing care for relatives with Alzheimer's disease to 15 non-caregivers; all received a small skin wound via punch biopsy, with healing times tracked.
• Results - Wounds in the caregiver group took an average of eleven days longer to heal compared to the control group.
• Conclusion - Long-term stress hinders the immune system's capacity to repair tissue effectively.
• Evaluation:
  • Sweeney (1995) replicated similar delays in caregivers for dementia patients.
  • Differences between groups might stem from factors like nutrition or rest patterns, not just stress.
  • The limited number of participants affects the findings' generalisability.