Selye’s General Adaptation Syndrome (GAS)

Introduction

Selye’s General Adaptation Syndrome (GAS) is a biological model that explains the physiological responses an individual experiences when exposed to persistent stressors. It describes a predictable three-stage pattern of physiological reactions.

KEY TAKEAWAY: GAS is a biological model describing the body’s response to stress over time.

The Three Stages of GAS

The GAS consists of three distinct stages:
1. Alarm Reaction
2. Resistance
3. Exhaustion

1. Alarm Reaction

The alarm reaction is the initial response to a stressor. It involves two substages:
* Shock: The body’s ability to deal with the stressor falls below normal. Physiologically, the body acts as if injured (e.g., body temperature and blood pressure drop).
* Counter Shock: The body rebounds from the shock phase. The sympathetic nervous system is activated, leading to a fight-flight-freeze response. Adrenaline is released, increasing heart rate and respiration.

REMEMBER: Alarm Reaction: “A” for Alert, the body initially alerts to the stressor. Think Shock and Counter Shock.

2. Resistance

If the stressor persists, the individual enters the resistance stage.
* The body attempts to adapt to the stressor and return to homeostasis.
* Physiological arousal remains high, but not as high as in the alarm reaction stage.
* The body uses resources (e.g., glucose, hormones) at an above-normal rate to cope with the stressor.
* Cortisol is released to further energize the body and repair damage.
* The individual appears to be coping, but the body’s resources are being depleted.

EXAM TIP: Resistance focuses on sustained coping, but at a cost.

3. Exhaustion

If the stressor continues for an extended period, the individual enters the exhaustion stage.
* The body’s resources are depleted.
* The individual’s ability to cope with the stressor declines significantly.
* The immune system is weakened, increasing susceptibility to illness.
* Physical and mental fatigue are common.
* Prolonged exhaustion can lead to serious health problems (e.g., cardiovascular disease, depression).

COMMON MISTAKE: Confusing resistance and exhaustion. Resistance involves coping, while exhaustion involves resource depletion and breakdown.

Diagram of GAS

(Description: A line graph showing resistance levels over time. The x-axis represents time, and the y-axis represents resistance levels. The graph starts at a normal resistance level, dips down during the shock phase of the alarm reaction, rises above normal during the counter shock and resistance stages, and then declines sharply during the exhaustion stage.)

Explanatory Power of GAS

The GAS explains how prolonged stress can lead to physiological damage and illness. It highlights the importance of managing stress to prevent the depletion of resources and the onset of health problems.

APPLICATION: Understanding GAS helps in designing stress management strategies that target specific stages of the stress response.

Strengths and Limitations of GAS

VCAA FOCUS: Be prepared to discuss both the strengths and limitations of GAS in exam questions.

Conclusion

Selye’s General Adaptation Syndrome provides a valuable framework for understanding the biological processes involved in the stress response. While it has limitations, it remains a significant contribution to the field of stress research.

STUDY HINT: Create flashcards for each stage of GAS, including key physiological changes and potential consequences.