Adaptation Theories and Models

Core Concepts

Cannon: fight-or-flight and homeostasis

Walter Cannon described the body's automatic reaction to threat: the fight-or-flight response, in which the sympathetic nervous system prepares the body for action — heart rate and breathing speed up, blood is redirected to muscles, and energy stores are mobilized. Cannon also popularized homeostasis: the body's tendency to maintain a stable internal environment despite outside changes. When the threat passes, the body normally returns to baseline. This model explains the physiologic machinery behind stress; it does not explain why a person feels stressed in the first place.

Selye: General Adaptation Syndrome (GAS)

Hans Selye showed that the body responds to a wide range of stressors with a predictable three-stage pattern, the General Adaptation Syndrome:

1. Alarm stage — the body recognizes the stressor and mobilizes defenses (the fight-or-flight response kicks in).
2. Resistance stage — the body adapts and copes with the stressor; the initial alarm signs fade while the body works harder than usual to maintain balance.
3. Exhaustion stage — if the stressor continues long enough, adaptive energy runs out; the body's defenses weaken and it may break down.

Selye also described the Local Adaptation Syndrome (LAS), a similar response limited to one body part (for example, inflammation at a site of injury). He distinguished eustress (stress perceived as positive, like a wedding or promotion) from distress (stress perceived as negative). Caveat: GAS is a physiologic model — it describes the body's stages, not the psychology of coping.

Lazarus and Folkman: the transactional model

Richard Lazarus and Susan Folkman argued that stress is not just in the event or the body, but in the transaction between person and environment. The key engine is cognitive appraisal: primary appraisal (what does this mean for me?), secondary appraisal (can I cope with it?), and reappraisal (updating judgments as things change). Coping comes in two broad flavors: problem-focused coping (changing the situation — making a plan, seeking information) and emotion-focused coping (managing the feelings — seeking comfort, reframing, venting). People typically use both; the "right" mix depends on whether the stressor can actually be changed. This model explains why perception and coping style, not just the event itself, determine stress.

Roy: the Adaptation Model

Sister Callista Roy views the person as an adaptive system that copes with environmental changes through two subsystems: the regulator (automatic neural and chemical responses) and the cognator (conscious perception, learning, and judgment). Stimuli arrive as focal (immediate, demanding attention), contextual (background contributing factors), and residual (beliefs, attitudes, past experiences). Adaptation happens across four adaptive modes: physiologic-physical, self-concept, role function, and interdependence. Health is successful adaptation in all modes; the nurse promotes adaptation by manipulating stimuli — for example, reducing the focal stimulus (pain) or strengthening contextual resources (family support).

Neuman: the Systems Model

Betty Neuman pictures the client as an open system surrounded by layers of defense. The flexible line of defense is the outermost buffer that can be stretched by stressors; the normal line of defense represents the person's usual steady state; the lines of resistance protect the basic structure (core) if the normal line is breached. Stressors are intrapersonal (within the person), interpersonal (between people), and extrapersonal (outside the person). Nursing care is organized as primary prevention (strengthening the flexible line so stressors never breach it), secondary prevention (intervening after a breach, once symptoms appear), and tertiary prevention (rebuilding strength after treatment). This model highlights prevention at every level.

Common Confusions