The primary function of the adrenocorticotropic hormone (ACTH) is to stimulate the production and release of cortisol from the adrenal glands. Cortisol plays a critical role in the body’s response to stress by regulating metabolism, enhancing glucose availability, and modulating immune functions. It is involved in the body's fight-or-flight response, helping maintain homeostasis during challenging situations. The secretion of ACTH itself is regulated by the hypothalamus and plays a vital role in the hypothalamic-pituitary-adrenal (HPA) axis.