An adrenal gland is two to three inches wide and about one-half inch high. Each adrenal gland is divided into two distinct structures, which are the inner medulla and the outer cortex. Each part of the adrenal gland secretes different hormones. While the adrenal medulla can be taken out without any life-threatening problems, the adrenal cortex controls essential metabolic processes that the human body cannot live without.
The adrenal cortex secretes about 30 steroid hormones, including cortisol, which regulates the body's metabolism of fat, protein and carbohydrates. The adrenal cortex is divided into three different layers, with each area producing a different type of hormone. The outermost section of the adrenal cortex secretes mineralocorticoids, primarily aldosterone, which helps the body conserve water. The middle region secretes glucocorticoids, which work to regulate blood glucose levels. The innermost region of the adrenal cortex secrete the gonadocorticoids, which are the sex hormones.
The adrenal medulla is developed from the body's neural tissue and secretes two different hormones, norepinephrine and epinephrine. These hormones are stimulated by the sympathetic nerve when a person is feeling intense stress, and are often called the "fight-or-flight" hormones. The adrenal medulla is also the primary source of dopamine, an essential neurotransmitter than can cause a host of problems, such as ADHD and fibromyalgia, when the levels are too low.
Adrenal fatigue is caused when the adrenal glands are not functioning at the optimum level. Adrenal fatigue typically develops after an individual suffers a long or extreme physical illness or emotional stress. During these times, the adrenal glands are overstimulated and can't keep up with the body's needs. Other names for adrenal fatigue include adrenal exhaustion, non-Addison's hypoadrenia, hypoadrenalism and sub-clinical hypoadrenia.
Hypoadrenalism is caused when the adrenal glands are underactive. Many symptoms of hypoadrenalism are caused by a deficiency of cortisol levels. Primary hypoadrenalism, called Addison's disease, is the result of adrenal gland failure. This is typically an autoimmune disease, which means the body's immune system produces antibodies to mistakenly attack the body's own tissues. Secondary hypoadrenalism, commonly referred to as adrenocorticotropic hormone (ACTH) deficiency, is caused by a disease of the pituitary gland that leads to adrenal failure. Hypoadrenalism can be fatal if not treated quickly.