The adrenal gland is a gland in most mammals. It is near the kidneys. Its name tells its position (ad – "near", and renes – "kidneys"). The gland is made up of two types of tissues: the centrally located tissue is called the adrenal medulla and outside this lies the adrenal cortex.

The adrenal glands are known as suprarenal glands in humans. In many animals the glands are next to the kidneys, but they are cap-like structures on top of the kidneys in humans.

The adrenal cortex produces three main types of steroid hormones: mineralocorticoids, glucocorticoids, and androgens. Mineralocorticoids (such as aldosterone) help in the regulation of blood pressure and electrolyte balance.

The adrenal gland makes hormones which control stress. It is involved in the production of steroid hormones. Among these hormones are cortisol and adrenaline.

The hormones secreted from the cortex region are called adrenocorticosteroids or corticoids. These are the hormones it makes:^[1]

• Corticosteroids: all corticosteroids are made from cholesterol.
  • Cortisol / cortisone. These two are in a reversible reaction: they can be changed to each other by an enzyme. Cortisol is the active version, cortisone is the inactive version.
  • Aldosterone: a hormone which regulates blood pressure.
  • Androgens: these are intermediate male sex hormones. They are turned into more active hormones in the testes.

The adrenal medulla, in the center of the gland, makes:^[1]

• Adrenaline (U.S = Epinephrine) and noradrenaline (U.S. = norepinephrine): they make the fight or flight response in animals.^[2][3]