Monday, August 13, 2012

The Adrenal Glands and The Stress Response

This summer has been kind-of stressful for me. I’ve been working extra hours at my day job and all the research and writing to bring The Verbal Herbal to life has been rewarding but overwhelming at the same time. I was letting myself get bogged down with so much stress it was beginning to affect my physical and emotional health. So this week, I’d like to talk about stress and fatigue and why it’s so important to be stress-free. Today, I want to talk about the physiology of stress and what is actually happening in the body.
The Adrenal Glands
The adrenal glands are two structures that sit on top of each of the kidneys. They are each about 2 inches long and weigh about 5 grams a piece.  Each gland consists of two very different parts: the medulla which is then surrounded by the cortex. Although they are considered I gland, the medulla and the cortex are very different structures. They even develop from different embryotic tissue.  Individually each part plays an important role in our body’s reaction to stress.
The Medulla
The medulla is the inner portion of the adrenal gland and developes from modified neurons. This area is in charge of handling the immediate response to stress. When there is a perceived stress in the environment the adrenal medulla is activated by the sympathetic nervous system, releasing adrenalin (epinephrine) and/or noradrenalin (norepinephrine) into the blood stream. As a result:  
  • heart rate and blood pressure increase
  • blood flow to the skin is constricted so that more blood can flow to the muscles
  • there is an increase of glycogen release from the liver, converting it to glucose and providing extra energy.
This is what is called the fight or flight response. For example, you see a bear in the woods, your body activates physiological changes to give you the best chance of survival. The fight or flight system becomes activated and you decide to run from the bear. If you run and the bear does not follow then you body recovers and you return to homeostasis. But if the stress continues, you continue to run and the bear continues to chase you, then the adrenal cortex becomes involved.
The Cortex
The adrenal cortex is the outer part of the adrenal gland and is developed from mesodermal cells which produce connective tissue. This area of the adrenal gland is responsible for releasing three main groups of hormones. Sex hormones are released here in small amounts and mineralocorticoids are released to regulate electrolyte balance in the body. The third group of adrenal cortex hormones is glucocorticoids. When the stressor continues, the bear keeps chasing you, glucocorticoids, like cortisol, are released. Cortisol has a number of effects on the body, the main goal being to keep you alive while the bear chases you. Here is a list of some of its actions: -
  • stimulates the liver to convert amino acids to sugar instead of protein thus providing ample energy,
  • increases protein breakdown to provide nutrients to the body,
  • suppresses the body’s inflammation response also decreasing allergic reactions and wound healing. This is important because if the bear injures you or you twist your ankle while you are running, the body continues to focus all of its resources on getting away.
When you are safe and the stressor, the bear, has retreated, the body can then recover and cortisol levels return to normal.
This was a brief rundown of the adrenal gland and their role in the stress response. In the next few days, I will discuss the pathological issues that stem from the stress response, what they do to the body and ways to fix the problem.

Cohen, B. J., Taylor, J. J., & Memmler, R. L. (2009). Memmler's structure and function
of the human body (9th ed.). Baltimore, MD: Wolters Kluwer Health/Lippincott William
& Wilkins.

Hoffmann, D. (2003). Medical herbalism: the science and practice of herbal medicine.
Rochester, Vt.: Healing Arts Press.


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