Definition

The adrenals are paired endocrine glands secreting catecholamines (norepinephrine and epinephrine) from the inner medulla, and steroid hormones from the outer cortex. The medulla is controlled by the neuroendocrine axis, while the cortex is controlled mostly by the pituitary gland. The adrenals are located retroperitoneally at the upper poles of the kidneys. They mainly help the body in its response to stress as well as play a role in maintaining blood pressure and salt balance. When faced with a stressful situation, the medulla of the adrenal glands secrete epinephrine (adrenaline) causing an “adrenaline rush” preparing the body for “fight or flight”.

This drawing reveals the intimate relationship between the adrenal glands (a.k.a. suprarenal glands) with the kidneys. Although they are paired, they usually appear quite different on cross sectional imaging.
Courtesy of: Ashley Davidoff, M.D.