Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 9/3/2004
Publication Date: N/A
Technical Abstract: The hypothalamic-pituitary-adrenal (HPA) axis refers to an organ system comprised of the hypothalamus, the pituitary gland, and the adrenal gland. The hypothalamus is an organ comprised of many separate nuclei and lies in the central nervous system below the thalamus. The pituitary gland lies below the hypothalamus and the two are connected by a tract of neurons called the hypophyseal stalk. The adrenal glands are a pair of endocrine glands which are located beside the kidneys, they are comprised of a medulla and a cortex. The term axis refers to the fact that these three organs are able to control one another by stimulating production of hormones as well as by terminating the production of hormones. The HPA axis has been the main focus of much research on the stress response, however it is important to remember that the HPA axis is always activated and thus measurement of any of its components does not indicate a definitive stress response. The function of the HPA axis is to help maintain homeostasis by regulating glucose availability.