What are the effects of acute stressors on the immune system? Are these effects just as relevant for ...

The immune system of our distant human ancestors had adaptive value for them of being responsive to the many acute stressors that might have resulted in bodily injury. For example, the sight of a predatory animal like a tiger would likely induce an acute stress response that would activate the immune system in anticipation of a bite from that animal. In the event of a bite from the predator, the immune system's ability to mobilize itself to fight pathogens carried in the saliva of the predator was very important. Preventing infection and accelerating wound healing through a strong immune response had then and still has adaptive value.

As you will recall from Chapter 3, during the fight-or-flight response, the sympathetic-adrenal medulla axis (SAM) and the hypothalamic-pituitary-adrenal (HPA) axis are activated, resulting in the release of catecholamines and glucocorticoids. Catecholamines, especially norepinephrine, temporarily boost immunological activity. Within minutes of experiencing an acute stressor the catecholamine hormones arouse the leukocytes to exit their barracks and travel through the blood stream. As the stress response continues, activation of the HPA axis results in the release of glucocorticoid hormones which induce leukocytes to exit the blood and take position at potential battle stations' (such as the skin, lung, gastrointestinal and urinary-genital tracts, mucosal surfaces, and lymph nodes) in preparation for immune challenges which may be imposed by the actions of the stressor.