The Endocrine Response to Stress

Reaction to stress is characterized by a series of interlinked, dynamic, and organized responses that function to restore homeostasis. Rapid activation of the sympathoadrenomedullary and hypothalamic–pituitary–adrenal (HPA) axes occurs following acute stress exposure in order to appropriately respond to, adapt, or escape the threat. The dynamic, pulsatile nature of the HPA axis is crucial to the function of glucocorticoids which modulate many of the complex neurocognitive and physiological changes that occur in acute and chronic stress states. Maladaptive long-term activation of the stress response is associated with numerous pathological states including mood and sleep disorders, obesity, and metabolic syndrome. The altered stress dynamics that occur in critical illness remain poorly understood.