What Does the Adrenal Gland Do?

The adrenal glands are also called suprarenal glands. These are endocrine glands that lie like caps on top of the kidneys.

Human kidneys with adrenal glands inside the body, 3D illustration - Illustration Credit: Kateryna Kon / Shutterstock
Human kidneys with adrenal glands inside the body, 3D illustration - Illustration Credit: Kateryna Kon / Shutterstock

Shape and structure

In human beings the right adrenal gland is triangular shaped while the left suprarenal gland is shaped like half a moon or semilunar in shape. Each of the glands are around 4 to 6 cm in length.

The outer part of the glands contains thick connective tissue capsule that sends thin fibers into the glandular tissues within. The glandular part is called the parenchyma. The parenchyma is divided into two major parts:

The cortex

The cortex secretes steroid hormones. The cortex contains cells that synthesize and secrete glucocorticoids, mineralocorticoids, and   certain gonadocorticoids (sex steroid hormones that are also produced in the gonads). These steroids are all derived from cholesterol.

Most of the cortex cells contain lipid inclusions or lipid portions. These lipids or fats are the basic molecules from which steroids are formed. The cells with their white fat globules appear like sponges and are thus called spongiocytes.

The cortex that three layers:

  • The Zona glumerulosa – Outer layer that is thin and looks like little balls of cells. They contain fewer lipids than other layers. The ZG cells secrete mineralocorticoid hormones. This hormone (mainly aldosterone) helps in maintaining the water balance and balance of electrolytes in the body. It acts on the kidneys, salivary and sweat glands to control reabsoprtion.
  • The Zone fasciculata – This layer forms around 80% of the whole cortex. These cells have typical spongiocyte appearance. The ZF cells secrete glucocorticoids including hormone cortisol. Cortisol is responsible for control of carbohydrate, protein and lipid metabolism. This layer also secretes sex steroids like androgens.
  • Zona reticularis – This is another thin layer. The cells are smaller than the ZF layer. This layer secretes androgens like dehydroepiandrosterone (DHEA), significant in males.

The medulla

The medulla secretes cathecholamines. The adrenal medulla has numerous capillaries and venules or thin arteries and veins.

Since these cells stain brown when exposed to chromium salts they are called chromaffin cells. There are two types of cells – E cells that sectrete Epinephrine (E) and NE cells that secrete Norepinephrine (NE). E and NE are cathecholamines that raise the heart rate, heart pumping capacity, blood pressure and rate of breathing. These are part of the “flight or fight” response in reaction to danger.

Hormones secreted by the Adrenal Glands:

The adrenal cortex secretes corticosteroids, such as glucocorticoids and mineralocorticoids. These hormones are responsible for responding to stress; using carbohydrates, fats and proteins; and regulating the salt and water balance in the body.

The adrenal medulla secretes both adrenalin and noradrenalin, also known as epinephrine and norepinephrine respectively. These hormones are involved in the body’s “fight or flight” response.

Further Reading

Last Updated: Jun 10, 2023

Dr. Ananya Mandal

Written by

Dr. Ananya Mandal

Dr. Ananya Mandal is a doctor by profession, lecturer by vocation and a medical writer by passion. She specialized in Clinical Pharmacology after her bachelor's (MBBS). For her, health communication is not just writing complicated reviews for professionals but making medical knowledge understandable and available to the general public as well.


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  1. Jeanne Phin Jeanne Phin United States says:

    My daughter was on a shot and steroids to treat depression, the shots were stopped abrubtley and she is now  fainting regularly and has to be on a rescue inhaler. steroids are very scary medications, massive weight gain, and the side effects are enormous.

  2. Margarita Aguirre Margarita Aguirre United States says:

    My Daughter is 24 years old her Adrenal Gland is not funnctioning properly and the endrocoloigst prescribed steroids. Her skin felt as if it was on FIRE, she called Dr. and he did not even try to help my Daughter! Come to find her dose is to high.

  3. Vivienne Taylor Vivienne Taylor United Kingdom says:

    I have adrenal hyperplasia and am on 3mg prednisone daily.  Do you suggest anything else I should do I AM 61YRS OLD

  4. Christine Ocallaghan Christine Ocallaghan Australia says:

    christine o'callaghan does an over active adrenal gland make people put on weight?

  5. Carol Dick Jenkins Carol Dick Jenkins Australia says:

    There is a great book 'Adrenal Fatigue'. It says to take Vitamin C tablets. Take the recommended amount 1st day and each day after add an extra one. When you start getting 'the runs' decrease back to the dose before and that is how many your body needs. Keep taking that does until you feel more normal. Then you can decrease again

  6. Donna Weigel Donna Weigel United States says:

    I have battled adrenal fatigue for years due to long term steroid use. I just wanted to say that I came across what looks to be promising for some help.  Check out Dr Eric Berg on  Youtube.  He so makes sense. I am hoping for the first time I might get some relief.  He is full of information.

  7. Natalie Eileen Smythe Natalie Eileen Smythe Australia says:

    I was born with cancer and my right adrenal gland was taken out I'm 18 now , I don't take any medications for this ? I'm worried I might need to ?

  8. Val Dyer Val Dyer United Kingdom says:

    i have been told i have a small swelling on my adrenal gland should i be worried.

  9. Alicia Horton Alicia Horton United States says:

    I had Cushing's Disease and after two tumor removals from my pituitary the surgeon could not get all the tumor cells so I opted to have my adrenals removed to save my life. I made an excellent decision and I am doing very well at 6 months post-op!

  10. Georgie richter Georgie richter Australia says:

    I have a being tumor on the adrenal gland.  I also have a low level on pituary gland my cholesterol is 7.5, I have suffered lots of stomach cramps etc.  after I have a meal my energy levels deplete very quickly I don't sleep very well as I am in pain most of the time.  I am currently on steroid injections, nobody knows what's wrong, I also have low iron, extra high calcium please can someone help me, I am now sinking into severe depression.

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News Medical.
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