Everyone talks about the adrenal glands and adrenal fatigue. So guess what? I’m jumping on the bandwagon! Because I’m a copycat? No, because it’s a really important topic!
The adrenal glands are two glands that sit on top of the kidneys, and they have two parts, the cortex and the medulla. The adrenal cortex is the outer part and it produces important hormones like cortisol and aldosterone. Cortisol helps regulate metabolism and participates in the stress response, and aldosterone assists in controlling blood pressure. The adrenal medulla is the inner part of the gland and it produces hormones like adrenaline which also participates in the body’s response to stress. It is adrenaline that prepares your body to spring into action when stress arises. The adrenals don’t only function in response to stress however, they produce hormones that enable us to live. The hormones produced by the adrenal cortex are essential to life, while those produced by the medulla are not [1, 2].
Two main groups of hormones are produced by the adrenal cortex and these are glucocorticoids and mineralcorticoids. The hypothalamus and pituitary glands stimulate the release of glucocorticoids, while the kidneys stimulate the release of mineralcorticoids. Corticotrophin releasing hormone (CRH) is produced by the hypothalamus and it stimulates the release of adrenocorticotropic hormone (ACTH) from the pituitary gland. This signals the adrenals to secrete corticosteroid hormones. Hydrocortisone and corticosterone are glucocorticoids released by the adrenal cortex. Hydrocortisone is more commonly known as cortisol. Cortisol regulates metabolism (conversion of fats, proteins and carbohydrates to energy), and it also helps regulate blood pressure and cardiovascular function. Corticosterone works together with cortisol to regulate the immune response and suppress inflammation .
Aldosterone is the main mineralcorticoid and it helps the body maintain salt and water balance, and helps control blood pressure .
Sex hormones are also released by the adrenal cortex, but in small amounts, and their impact tends to be trumped by hormones like testosterone and estrogen which are released by the testes and ovaries respectively .
So clearly we can see the importance of the hormones secreted by the adrenal cortex and why they are necessary to support life.
The adrenal medulla hormones are released when the sympathetic nervous system is stimulated and this occurs in times of stress. This is where the fight or flight response comes into play. This process is initiated by the sympathetic nervous system when the body is presented with a stressful/threatening situation and the hormones produced by the adrenal medulla contribute to this response. Epinephrine and norepinephrine are the hormones here. Epinephrine is also known as adrenaline and when the body encounters stress, it is responsible for increasing heart rate and providing more blood to the muscles and brain. It also causes a spike in blood sugar as it plays a role in stimulating the conversion of glycogen to glucose [in the liver]. Norepinephrine is also known as noradrenaline and it helps epinephrine respond to stress. It can however lead to vasoconstriction with can lead to high blood pressure [1, 2].
Stress can be linked to a number of health issues including high blood pressure, heart disease and digestive problems for example. Stress leads to hormonal changes and changes in blood sugar, and it can cause the body to excrete nutrients and can adversely affect the immune system. The adrenal glands appear to respond to stress in stages. The first stage involves enlargement of the adrenals due to an increased blood flow to them. With continued stress the adrenals shrink, and beyond that, adrenal exhaustion sets in .
The stress response is meant to be transient however in our modern times this isn’t the case. Our overworked adrenals don’t get a chance to recover between bouts of stress, because there is frequently no ‘between’, so the overproduction of adrenal hormones persists. This can lead to a decrease in immune system function, decreased blood flow to the digestive tract (causing indigestion, and IBS), and an increase in blood clotting ability (leading to atherosclerotic plaque formation and heart disease) .
In terms of the stages, when someone with otherwise healthy adrenals is in the first stage they can function well as needed. With continued stress the body enters a resistance stage and this is where the adrenals become enlarged. Here too the person may be responding to and handling stress but they may also feel amped up and may have cold, clammy hands and a fast pulse, might have a decreased appetite but otherwise doesn’t have serious symptoms… yet. When in the exhaustion stage, the adrenals start to fail as they struggle to meet the demands placed on them. Symptoms of this stage include fatigue, digestive problems, obesity, depression, dizziness, fainting, allergies and other issues .
Those with overworked adrenals may crave coffee, sugar and salt. Sugar and caffeine stimulate the adrenals .
Have you heard of the HPA axis? It’s the hypothalamic-pituitary-adrenal axis. Corticotropin releasing factor (CRF) plays an important role in the stress response because it regulates the HPA axis. CRF initiates a cascade of events in response to stress that results in the release of glucocorticoids from the adrenal cortex, which lead to a number of different effects in the body. Feedback inhibition by glucocorticoids has an important role in the regulation of the magnitude and the duration of the release of glucocorticoids. The HPA axis is also regulated at the level of the hypothalamus, and the stress response is mediated in the brain stem by a variety of mechanisms .
When the stress response is activated, it initiates behavioral and physiological changes that provide an individual with a leg up if you will when it comes to survival in the face of challenges to homeostasis in the body. Behavioral changes include increased awareness, increased cognition, and even euphoria. Physiological changes include increases in cardiovascular tone, rate of respiration and intermediate metabolism. Other functions like digestion, growth, immunity and reproduction are inhibited. When stress persists, the stress response can result in pathogenic effects. For example, in order to maintain homeostatis in a state of stress, the body activates a range of responses that involve the endocrine, nervous and immune systems, and if the regulation of the stress response is inappropriate a number of conditions can develop including autoimmune disease, high blood pressure, affective disorders and even major depression . The body was never meant to sustain the stress response, it is only there for us as a transient means for dealing with stress. And that my friends, it what all the fuss is about!
In addition to the information I’ve provided here, I was contacted by the author of a great book (and blog) that provides a ton of awesome detail on this subject. Check out The Adrenal Fatigue Solution! http://adrenalfatiguesolution.com/