Hypothalamic–Pituitary–Adrenal (HPA) Axis

The hypothalamic–pituitary–adrenal axis (HPA axis) is a network of endocrine glands: the hypothalamus, the pituitary gland, and the adrenal gland. The interactions among these organs are a major part of the neuroendocrine system that supports the body’s response to stress, mood, and emotional functioning, as well as regulating other biological functions related to digestion, the immune response, and the storage and expenditure of energy. This entry focuses on the role of the HPA axis in the response to and management of stress, specifically covering how the HPA axis supports the human responses to stress for immediate and long-term survival, factors that affect the HPA axis across the lifespan, and outcomes associated with atypical HPA axis functioning.