Hypothalamic–pituitary–adrenal axis Hypothalamic–pituitary–adrenal axis The hypothalamic–pituitary–adrenal axis (HPA axis or HTPA axis) is a complex set of direct influences and feedback interactions among three components: the hypothalamus, the pituitary gland (a pea-shaped structure located below the thalamus), and the adrenal (also called "suprarenal") glands (small, conical organs on top of the kidneys). These organs and their interactions constitute the HPA axis, a major neuroendocrine system that controls reactions to stress and regulates many body processes, including digestion, the immune system, mood and emotions, sexuality, and energy storage and expenditure. It is the common mechanism for interactions among glands, hormones, and parts of
Pituitary gland referred to the pituitary gland by only using the (Ancient Greek) name ἀδήν, "gland". He described the pituitary gland as part of a series of secretory organs for the excretion of nasal mucus. Anatomist Andreas Vesalius translated ἀδήν with "glans, in quam pituita destillat", "gland in which slime ("pituita") drips". Besides this 'descriptive' name, Vesalius used "glandula pituitaria", from which the English name "pituitary gland" is ultimately derived. The expression "glandula pituitaria" is still used as official synonym beside "hypophysis" in the official Latin nomenclature "Terminologia Anatomica". In the seventeenth century the supposed function of the pituitary gland to produce