The NeuroEndoMetabolic (NEM) Stress Response System is your body’s natural stress-fighting system. It is a delicate network of various organs and six circuits that work in close unison. Under stressful situations, the hypothalamic-pituitary-adrenal (HPA) axis, which is a component of the NEM stress response system, signals your adrenal glands for producing anti-stress hormone cortisol.