Body Basics: What Are Adrenal Glands and What Do They Do?
The human body is extraordinarily complex, which can make it intimidating to try to understand. In fact, although we don’t truly understand all of it, we do know a lot about how it works. But you don’t have to be a physician or have a PhD in physiology to have a basic understanding of how your body works and what you can do to make it be as healthy as possible.
This article is part of the Thorne series we call “Body Basics” – and is designed to make your learning about the body less intimidating. By learning more about how the body works you can make informed decisions about your health, whether you are at home, the store, your health-care practitioner’s office, or online.
The adrenal glands
The well-known “adrenaline rush” – some people deliberately seek it out, some actively avoid it. It is a phenomenon that almost everyone will experience at some point.
Often, the adrenaline rush is the only reason to be aware you have adrenal glands.
So you might be surprised to know that the adrenal glands are actually critical to multiple normal body functions besides stress.
What are the adrenal glands?
The adrenal glands, located in the middle of your torso toward the back, are two somewhat triangular structures that rest on top of the kidneys like little hats. The adrenal glands are part of your endocrine system, which controls body functions using hormones.
Hormones are chemical signals transported in the blood to their targets in the cells, tissues, and organs. After reaching its target, the hormone causes changes in how the target functions.
Most body systems try to keep the body in balance, working within normal operating parameters. Many of the hormones produced by the adrenal glands follow this model – bringing the body back in balance when something throws it off.
However, the adrenal glands can, under certain circumstances, throw the body out of its day-to-day balance on purpose.
What hormones do the adrenal glands make?
Each adrenal gland has two primary parts – an inner core called the medulla and an outer shell called the cortex. Each part produces different hormones. The major hormones produced by the adrenal glands are:
What do the adrenal hormones do?
1. Epinephrine and Norepinephrine
The most familiar function of the adrenal glands, the "adrenaline rush," is part of an emergency system called the stress response, which shifts resources to critical body functions in an emergency.
This response can be generated on purpose, such as by riding a roller coaster or whitewater rafting, or unintentionally such as being in a car accident or when you see a child chase a ball into the street.
This complex reaction to danger (real or perceived) is coordinated by your brain and your adrenal glands.
You might have heard this response called “fight or flight. When this stress response is triggered the adrenal glands release epinephrine and norepinephrine from the medulla, thus generating the familiar adrenaline rush.
In combination with cortisol from the cortex, the adrenal hormones move the body away from its usual balance (normal-normal) toward a different balance (stress-normal) that redirects resources to critical emergency-response systems and away from non-essential systems.
In stress-normal status, heart rate, blood pressure, and blood flow are adjusted upward so more blood flow goes to the brain, muscles, and lungs. These hormones also cause the body to stop acquiring energy (because eating and digestion are “slow” processes) and to release stored energy (which is available quickly).
This ensures there is plenty of fuel (especially glucose) for those cells that need to work harder and faster than normal to cope with the emergency in the short-term. All this, in conjunction with effects from the nervous system, causes you to become very alert, perhaps momentarily faster or stronger than usual, while feeling less pain.
But while the emergency systems are being supercharged, the rest of the body systems actually slow down during stress-normal.
For example, there's only so much blood volume in the body, so sending more to the brain and muscles means that less goes to other systems like the digestive and reproductive tracts. The immune system is also deactivated, so many responses to damage, like inflammation, that would normally occur right away are delayed.
The body is only built to function in stress-normal status for a short period, and is then supposed to return to normal-normal. When stress triggers are prolonged, such as might occur with adverse work situations or a loved one's prolonged illness, this can begin to cause damage to the body.
When the body is under stress, cortisol participates with epinephrine and norepinephrine in the stress response. Cortisol increases blood pressure and the availability of blood sugar (glucose) for energy. Higher levels of cortisol also slow bone formation, which can impact growth and repair when the stress-normal condition is prolonged.
Cortisol also suppresses the immune system.
This might be beneficial, for example, in the middle of a physical emergency when it could be helpful for your knee joint not to swell up so you can keep running despite an injury.
It might not be so helpful when the stress is emotional, such as might occur before a final exam, making it harder to fight off a cold that’s going around because the cortisol is preventing your immune system from responding to the invading virus.
What’s worse, chronic stress can become a significant adverse health issue when cortisol levels remain consistently high and the immune system is constantly prevented from fully functioning, especially in the context of the other disruptions to normal that go along with stress-normal status.
When the body is not under stress, small amounts of cortisol from the adrenal cortex helps regulate numerous critical body systems by keeping their function within a healthy range.
At normal-normal levels, cortisol influences the way the body regulates blood sugar.
Cortisol also influences blood pressure and immune function in positive ways at low levels, and it also supports bone formation when it is at low, normal-normal levels.
Interestingly, our cortisol levels naturally fluctuate throughout the day. For individuals with a typical schedule (awake during daylight hours), cortisol levels should be highest in the morning (this can be reversed in night shift workers).
This natural up and down cycle (called the circadian rhythm) helps coordinate other body functions that occur on a cycle – like when you feel awake versus sleepy. Cortisol levels that are out of balance or don’t follow this normal pattern can have a negative influence on sleep.
Something else to keep in mind when thinking about the effect of cortisol on the body is that nearly every cell has cortisol receptors. This means the behavior of these cells will be altered by cortisol levels.
While there are some effects, like wakefulness and blood pressure, that are easy to see and measure, it is likely that cortisol has broad-based effects in the body in combination with other signals that are harder to see and understand, but nevertheless have an influence on health.
That’s one good reason, among many, to make the effort to keep your cortisol levels in the normal-normal range as much as possible.
Aldosterone is another hormone produced by the adrenal cortex. Aldosterone’s primary role is to regulate blood pressure by influencing how much sodium and potassium the kidneys leave in or remove from the blood.
This process affects electrolyte balances and influences the amount of blood in your body, which, in turn affects how full the blood vessels and heart are, which affects blood pressure. This process can also have an effect on blood pH (the acidity of the blood).
4. Androgenic steroids
Androgenic steroids, or androgens, are more commonly known as male sex hormones because they are produced in largest quantity in the testes, and their most obvious functions are related to male characteristics like muscularity, body hair, and male reproduction.
But androgens are also produced in both males and females in smaller quantities from other tissues, including the adrenal cortex.
The most abundant of this class of steroids produced by the adrenal cortex is DHEA (dehydroepiandrosterone), which is best understood as a precursor molecule. A precursor molecule is comparatively inactive on its own, but is converted into another sex hormone in other locations in the body in order to exert its effects.
For example, both estrogen and testosterone can be produced from DHEA. There is also evidence that DHEA helps balance the effects of cortisol, thus keeping stress-normal in check and helping return the body to normal-normal status.
So those two funny little glands sitting on your kidneys, that you might not have known anything about before today, are actually critical to life. The hormones produced by the adrenal medulla are the first on the scene in a very stressful situation.
On the other hand, the hormones produced by the adrenal cortex, although associated with stress, are more important to normal body function and basic life processes regulating blood pressure, influencing metabolism and the immune system, and supporting the stress response.
How are your adrenal glands functioning?
Consider Thorne’s At-Home Stress Test Kit – a simple saliva-based test that measures your cortisol fluctuations throughout the day, as well as your DHEA levels. You may also consider nutritional support for your adrenal glands and supplementation to help balance your cortisol and help you chill.