The occurrence of heightened chronic stress can cause an individual to produce and continue to release stress hormones, such as glucocorticoids, that eventually damage the affected individual’s immune system. Why has such an obviously costly response evolved?

Stress is the body's response to condition such as a threat, challenge or physical and psychological barrier It involves the response of the body to stimuli as a result of activity that alters the body environment.

Autonomic nervous system and hypothalamic pituitary adrenal (HPA) axis are the two major systems that respond to stress in humans and some animals.

In response to stress fight or flight response is activated through the sympathetic nervous system this dedicates energy to more relevant bodily systems to acute adaptation to stress while the parasympathetic nervous system helps the body to maintain homeostasis this is done by regulating the release of cortisol, which influences many bodily functions such as metabolic, psychological and immunological functions.

Steroid hormones bind to glucocorticoid receptors in the brain to providing negative feedback by reducing( Adrenocorticotropic hormone) ACTH.

Glucocorticoid produce is a response to the negative feed back gotten from stress and it is done to help maintain a balance in the body system which is homeostasis. It moves energy into the bloodstream from storage sites in the body and increase cardiovascular tone.