The adrenal gland, located on top of the kidneys, is made up of two parts with very distinct hormonal functions. The adrenal cortex is the outer part of the gland and it produces hormones that help regulate metabolism and immune response, among other things. The inner part of the gland, called the adrenal medulla, secretes important hormones for coping with stress. It is the release of adrenalin (or epinephrine) that triggers the "fight or flight" response. If you've ever been afraid and found you could run faster than you ever would have thought, that's adrenalin.