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get to know your adrenal glands

Get to Know Your Adrenal Glands

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November 23, 2020 | Published by


The last, but certainly not least, part in our Get to Know Your HPA Axis series is the adrenal glands (we previously covered the hypothalamus and pituitary). If you’ve ever experienced stress or adrenal fatigue, you certainly know about the adrenal glands. But just how much do you know about the ‘glands of stress?’

Location of the Adrenal Glands

The adrenal glands are each about the size of a walnut and are located atop the kidneys. Their name is actually derived from their location; ad is Latin for near or at, and renes is Latin for kidneys. Like the previous two glands of the HPA axis, the adrenal glands are composed of two main parts. There’s the adrenal cortex and adrenal medulla. The adrenal cortex, the outer region, is the larger part of the adrenal gland. The cortex itself is divided into three zones: zona glomerulosa, zona fasciculata, and zona reticularis. Each of these zones release different hormones.1

The adrenal medulla is located in the middle of the gland inside the cortex. This is where stress hormones such as adrenaline and cortisol are produced. Both the cortex and medulla are covered in a protective layer called the adipose capsule.2

Both adrenal glands are only a very short distance from the aorta, the major artery of the body, and the vena cava, the major vein. This strategic placement allows for a very rapid adrenal response to hormonal messages transported via the blood. For example, Adrenal Corticotrophic Hormone (ACTH) is a hormone messenger from the pituitary gland that tells the adrenal glands how much cortisol to secrete. Within a few seconds of receiving this message the correct level of cortisol is on its way from the adrenals to the rest of the body.3

Function of the Adrenal Glands

As we mentioned in part 2 of this series, the adrenal glands are controlled by the pituitary. Like the other glands in the HPA axis, the adrenal glands are responsible for a number of hormones that are vital to different functions and processes in the body. For example, aldostreone helps control blood pressure by managing the levels of certain electrolytes in the body. Cortisol, along with adrenaline and noradrenaline, help the body respond to stress. Cortisol also helps regulate metabolism, blood sugar levels, and blood pressure, among other things. We look at the hormones of the adrenal glands in further detail in the next section.4

Hormones of the Adrenal Glands

Let’s start with the hormones produced by the adrenal medulla. Believe it or not, you don’t need the adrenal medulla to survive. However, that doesn’t mean the medulla is totally useless. The hormones produced by this region are released after the sympathetic nervous system is stimulated, which happens when you experience stress. Therefore, the medulla is part of the fight or flight response responsible to reacting to physical and emotional stress. The medulla produces two main hormones: epinephrine and norepinephrine.1

  • Epinephrine – You’ll likely know this hormone by it’s other name, adrenaline. As you likely know and have experienced, adrenaline quickly responds to stress by increasing heart rate and pushing blood to the brain and muscles. Epinephrine also causes blood sugar levels to jump by helping convert glycogen to glucose in the liver.
  • Norepinephrine – This hormone, also known as noradrenaline, works alongside adrenaline in the stress response. However, norepinephrine can also cause the blood vessels to narrow, which results in high blood pressure.

The adrenal cortex is essential to survival and produces three major hormones: mineralocorticoids, glucocorticoids, and adrenal androgens.

  • Mineralocorticoids – The most important of these hormones is aldosterone, which helps to maintain the body’s salt and water levels which, in turn, regulates blood pressure. Without his hormone, the kidney loses mass amounts of sodium, then water, which leads to severe dehydration and low blood pressure.5
  • Glucocorticoids – The predominate hormone in this group is cortisol, which is involved in many processes including the response to illness and regulating metabolism. By stimulating glucose production, cortisol helps stimulate glucose production. Cortisol is also the body’s chief anti-inflammatory agent.5
  • Adrenal androgens – These are comprised of male sex hormones, mainly dehydroepiandrosterone (DHEA) and testosterone. These hormones have relatively weak effects, but play a vital role in the early development of males and females during puberty.5

More on Cortisol

Since cortisol is so vital to the stress response, let’s talk a bit more on the role the adrenal glands play in the production of this hormone. Specifically, cortisol is produced by the zona fasciculata. In addition to the roles outlined above, cortisol also helps control the body’s use of fats proteins and carbs, and also controls the sleep/wake cycle. Here’s a step-by-step outline of how cortisol is produced and released.2

  1. The hypothalamus produces corticotropin-releasing hormone (CRH), which signals to the pituitary gland to release adrenocorticotropin hormone (ACTH).
  2. ACTH then signals the adrenal glands to make and release cortisol into the blood.
  3. Typically, both the hypothalamus and pituitary can sense if there’s an adequate amount of cortisol circulating in the blood. If there’s too much or too little cortisol, these glands change the amount of CRH and ACTH released, respectively. This process is called a negative feedback loop.

Tips to Support the Adrenal Glands

Like with the hypothalamus and pituitary, there are things you can do to help support your adrenal glands. We have lots of helpful information on our blog on how to support the adrenal glands, especially during stress. Diet also plays a big part in supporting these glands, and you can find our diet for stress tips here. Reducing and better managing stress is a huge part of supporting the adrenal glands as well. You can find Dr. Wilson’s Guide to De-Stressing here.

References:

  1. Sargis, R, MD. An Overview of the Adrenal Glands. Endocrine Web. https://www.endocrineweb.com/endocrinology/overview-adrenal-glands
  2. Adrenal Glands. Johns Hopkins Health. https://www.hopkinsmedicine.org/health/conditions-and-diseases/adrenal-glands
  3. Wilson, James, ND, DC, PhD. Adrenal Fatigue: The 21st Century Stress Syndrome.
  4. Cherney, K. Adrenal Glands. Healthline. https://www.healthline.com/health/adrenal-glands
  5. Adrenal glands. You and Your Hormones/Society for Endocrinology. https://www.yourhormones.info/glands/adrenal-glands/

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