Adrenal gland
The adrenal glands (also known as suprarenal glands) are endocrine glands that produce a variety of hormones including adrenaline and the steroids aldosterone and cortisol. They are found above the kidneys. Each gland has an outer cortex which produces steroid hormones and an inner medulla. The adrenal cortex itself is divided into three zones: the zona glomerulosa, the zona fasciculata and the zona reticularis.
Adrenal insufficiency
Adrenal insufficiency can also occur when the hypothalamus or the pituitary gland does not make adequate amounts of the hormones that assist in regulating adrenal function. This is called secondary or tertiary adrenal insufficiency and is caused by lack of production of ACTH in the pituitary or lack of CRH in the hypothalamus, respectively.