Hypothalamic pituitary adrenal axis
The hypothalamic pituitary adrenal (HPA) axis describes the relationship between the hypothalamus, anterior pituitary gland, and adrenal glands in the sequential production of various hormones from each of these three glands, including corticotropin-releasing hormone (CRH), ACTH, and cortisol, respectively.
CRH is made in the hypothalamus and is released via a local capillay plexus into the anterior pituitary. This in turn stimulates the production of ACTH in the anterior pituitary gland, and ACTH is released into the systemic circulation. Psychological and physical stress, including trauma, surgery, hypoglycemia, fever, and exercise, can all increase the production of ACTH. Like other hormones released from the pituitary, ACTH is released in a circadian fashion, with peak levels occurring about 8 am and nadirs occuring about midnight.
ACTH acts on the adrenal glands through specific cell membrane receptors in the adrenal cortex to drive the release of...
- Niewoehner CB (1998) Endocrine Physiology. Fence Creek Publishing, MadisonGoogle Scholar