major component of the stress system consisting of the paraventricular nucleus (PVN) of the hypothalamus, the anterior pituitary gland, and the adrenal cortices. Corticotropin-releasing hormone and vasopressin secreted by PVN neurons into the hypophysial portal system stimulate pituitary cells to produce and secrete adrenocorticotropic hormone (ACTH) into the general circulation. ACTH then stimulates cortisol secretion by the adrenal glands.
