The hypothalamus, pituitary and adrenal glands make up the HPA axis, which play a major role in the stress response. In fear or anger, the hypothalamus releases corticotropin-releasing hormoneto the pituitary gland.  The pituitary then sends adrenocorticotropic hormones to the adrenal glands to release cortisol, the stress hormone.  Cortisol is a glucocorticoid hormone. It functions to metabolize, fat, protein and carbohydrates.  The stress response allows for energy to be converted quickly.  Just think when you are stressed, what is going on in your body. Yourblood pressure goes up, heart rate increases, and glucose is dumped into your system.  In fear we get ready to fight or make flight.