The
hypothalamic–pituitary–adrenal axis (
HPA axis or
HTPA axis), also known as the
limbic–hypothalamic–pituitary–adrenal axis (LHPA axis) and, occasionally, as the
hypothalamic–pituitary–adrenal–gonadotropic axis, is a complex set of direct influences and
feedback interactions among three
endocrine glands: the
hypothalamus, the
pituitary gland (a pea-shaped structure located below the hypothalamus), and the
adrenal (also called "suprarenal") glands (small, conical organs on top of the kidneys).