Situation: The nurse teaches a stress-management class for adults attending the outpatient mental health clinic. A participant asks why her heart pounded, her palms sweated, and her blood sugar rose during a sudden family crisis. Which explanation is accurate?

The alarm stage of the general adaptation syndrome is the fight-or-flight response: sympathetic activation raises heart rate and sweating, and cortisol release raises blood glucose. Resistance and exhaustion follow only if the stressor continues.

The alarm stage is the first phase of the general adaptation syndrome described by Selye, and it corresponds directly to the fight-or-flight reaction that Cannon linked to catecholamine release ^[1]. When a sudden family crisis occurs, the brain perceives a threat and immediately activates two coordinated pathways: the sympathetic-adrenomedullary system and the hypothalamic-pituitary-adrenal axis.

Sympathetic activation releases epinephrine and norepinephrine, which rapidly increase heart rate, contractility, and sweat gland activity, producing the pounding heart and sweaty palms the participant experienced. At the same time, the hypothalamus triggers corticotropin-releasing hormone, which leads to adrenocorticotropic hormone release and subsequent cortisol secretion from the adrenal cortex ^[1][2]. Cortisol raises blood glucose by promoting gluconeogenesis and reducing peripheral glucose uptake, ensuring that fuel is available for muscles and the brain during the perceived emergency ^[2].

The acute activation of the HPA axis is adaptive and protective in this context ^[2]. The body is mobilizing energy and cardiovascular reserve to respond to an immediate threat. This is not a sign of pathology; it is the expected physiological response to an acute stressor.

Stage	Physiological response	Clinical correlate
Alarm stage	Sympathetic surge, catecholamine release, cortisol elevation, hyperglycemia, diaphoresis, tachycardia	Fight-or-flight response; the symptoms described by the participant
Resistance stage	Hormone levels remain elevated but the body attempts adaptation; glucose and cortisol may stay above baseline	Occurs only if the stressor persists beyond the initial alarm
Exhaustion stage	Depletion of adaptive energy, possible HPA dysregulation, increased vulnerability to illness	Develops after prolonged or repetitive stress, not during a sudden acute crisis

Watch out! The resistance and exhaustion stages do not explain the immediate symptoms. They follow only when the stressor continues over time ^[1]. The parasympathetic system would produce the opposite effects—slowing the heart and reducing arousal—so it cannot be the source of a fight-or-flight presentation.

Key point! The alarm stage is the acute, adaptive stress response driven by sympathetic activation and cortisol release, and it accounts for the tachycardia, diaphoresis, and elevated blood glucose seen during a sudden crisis. Chronic or repeated HPA activation, by contrast, contributes to allostatic load and maladaptive metabolic changes, which is a separate concern from the acute alarm reaction ^[2].