stress response
Summary
The stress response is the body's physiological and psychological reaction to a stressor, driven by a fast sympathetic pathway (epinephrine) and a slower HPA axis that releases cortisol. Most testable: it follows appraisal of the threat, and Selye's three stages end in exhaustion if the stressor persists.
Detail
Meaning: A stressor is any event appraised as threatening or demanding. In Lazarus's appraisal model, primary appraisal asks whether the event is a threat, and secondary appraisal asks whether you can cope. Two systems then act. The fast pathway is sympathetic: the hypothalamus activates the nervous system, and the adrenal medulla releases epinephrine and norepinephrine. Heart rate, blood pressure and blood glucose rise (fight-or-flight). The slower pathway is the HPA axis: hypothalamus (CRH) → anterior pituitary (ACTH) → adrenal cortex (cortisol). Cortisol mobilizes energy, and when it stays high it suppresses immune function.
Selye's general adaptation syndrome describes the course over time: alarm, resistance, then exhaustion.
On the MCAT: Passages describe a stressor, such as an exam or an animal restraint experiment, and ask which hormone or system rises first, which stage a person is in, or why chronic stress is linked to illness. Cortisol is the usual stress marker in a figure. Questions may also contrast eustress (positive, motivating) with distress.
Common confusion: Students mix up the two pathways. Epinephrine comes from the adrenal medulla under direct neural control and acts within seconds. Cortisol comes from the adrenal cortex under hormonal control and acts over minutes to hours. The resistance stage is not a calm state, because arousal and cortisol remain elevated while the body copes.
Sources
- Psychology
- Health Psychology
Written for the MCAT and checked before it was published. For study reference only. Spotted an error? Let us know.