The hypothalamic-pituitary-adrenal axis (HPA axis) is a complex network involving the hypothalamus, pituitary gland, and adrenal glands. It plays a crucial role in the body's response to stress. When faced with a stressor, the hypothalamus releases corticotropin-releasing hormone (CRH), which signals the pituitary gland to produce adrenocorticotropic hormone (ACTH). ACTH then stimulates the adrenal glands to release cortisol, a hormone that helps manage stress and maintain homeostasis. The HPA axis is essential for regulating various bodily functions, including metabolism, immune response, and mood. Dysregulation of this axis can lead to health issues such as anxiety and depression.