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Psychology · Chapter 13

Stress and the Body

The stress response that saves your life in an emergency turns corrosive when it never shuts off. Chronic stress keeps cortisol and the sympathetic nervous system switched on — and, as neuroscientist Robert Sapolsky put it in Why Zebras Don’t Get Ulcers, the very system that helps a zebra outrun a lion quietly wears down a human who is stressed for months. Tap each body system to see what unrelenting stress does to it.

A body under chronic stress

Tap a marker — or a system in the list — to see the damage.
One driver, seven targets.
The body under chronic stresstap a system to begin
One switch, many casualtiesAcute stress is adaptive — a burst of energy that helps you cope and then fades. The damage comes from chronic activation: the HPA axis and sympathetic nervous system stay switched on for weeks or months, and elevated cortisol reaches nearly every organ. Tap a system to see its specific injury.
HPA axis: Hypothalamus → Pituitary (ACTH) → Adrenal cortex → cortisol. The adrenal medulla adds the fast hit — epinephrine & norepinephrine. In an emergency this is lifesaving; kept on for months it corrodes.
Allostatic load: Physiologist Bruce McEwen named the cumulative “wear and tear” from a stress response that never resets. Hans Selye earlier called the resulting illnesses the diseases of adaptation. Much of the harm eases once the stressor lifts — the body wants to recover.