The American Association of Endocrine Surgeons, Patient Education Site

Background: Function of the
adrenal glands

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What do the adrenal glands do?

The medulla is located in the center of the gland and makes adrenalineAdrenaline - the hormone that helps control the "fight or flight" response and puts the body on "high alert" (also known as epinephrine) and noradrenaline. These hormones are also known as epinephrine and norepinephrine. These hormones control the "fight or flight response" i.e. put your body on "high alert." These hormones increase the heart rate, increase blood pressure, increase the amount of oxygen you breathe in, and temporarily improve the eyesight. Adrenaline also causes the liver to release extra glucoseGlucose - sugar used by the body as energy, or sugar, into the bloodstream to provide instant energy. Things that cause the adrenal medulla to release adrenaline and noradrenaline include anxiety, pain, upright posture, exercise, and cold. Once released, these hormones are broken down into normetanephrine and metanephrines, which are metabolites or waste products.

The cortex is located on the outer layer of the adrenal gland and makes a number of different hormones that help control the heart, kidneys, GI tract, bones, genitalia, and immune system. These hormones control carbohydrate metabolism, muscular integrity, hemodynamic changes, and sexual maturity. The cortex makes 3 main types of hormones:

  1. CortisolCortisolCortisol - a glucocorticoid that controls glucose production and suppresses the immune system is a glucocorticoid. Glucocorticoids are hormones that control glucose production in the liver and protein breakdown in muscle. These hormones also decrease the immune response by suppressing inflammation and other parts of the immune system. The most powerful glucocorticoid is cortisol, which the body needs to function normally as well as to protect the body during stress.
  2. AldosteroneAldosteroneAldosterone - a mineralocorticoid that controls blood pressure is a mineralocorticoid. Mineralocorticoids are hormones that control blood pressure by controlling the amount of fluid that the body holds onto. Aldosterone is the most powerful mineralocorticoid and causes the kidneys to hold onto more sodium, which leads to increased total body fluid. The more fluid the body holds onto, the higher the blood pressure may become. Aldosterone also directly affects the heart and blood vessels.
  3. Androgens and estrogen – Androgens and estrogens are sex-hormones. These hormones control the growth of the reproductive organs (testicles and ovaries), development of male or female characteristics, and some parts of behavior. Androgens control the male reproductive system while estrogens control the female reproductive system.

Diseases of the adrenal glands usually are caused by either too much or too little of any of these hormones. Adrenal insufficiency occurs when the adrenal gland is not producing enough hormones and is also called Addison's diseaseAddison's disease - a disease where not enough of the adrenal hormones are being made. This problem is also known as adrenal insufficiency.. Addison's disease is potentially fatal if the patient does not receive hormones in pill form. The adrenal gland may make too much of any one of these hormones and cause any of the following diseases: Cushing's syndromeCushing's syndrome - a disease where too much cortisol is being made (too much cortisol), primary hyperaldosteronismPrimary hyperaldosteronism - a disease where too much aldosterone is being made (too much aldosterone), virilizing syndromeVirilizing syndrome - a disease where too much androgen (male sex hormoneHormone - a chemical made by a gland that travels in the bloodstream and "tells organs what to do.") is being made (too much androgen), pheochromocytomaPheochromocytoma - a disease where too much adrenaline is being made by an adrenal tumor (too much adrenaline), and paragangliomaParaganglioma - a disease where too much adrenaline is being made by a tumor outside the adrenal glands (too much adrenaline). Please see the individual sections for more information.

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