The Endocrine System: The Adrenal Glands and the Stress Response (2023)

Posted on 3/19/20 by Laura Snider

Stress is a pretty big deal in modern society. Most of us spend a lot of time either feeling it, trying to relieve it, or both.

So, what is stress? At its core, stress is all about how the body reacts to a potential threat. The fight-or-flight (or fight-flight-freeze) response, aka the “alarm” stage of the stress response, is there for a good reason—it prepares the body to deal with danger (you know, like outrunning a ferocious animal that’s trying to eat you, or fighting off a fellow cave-person coming at you with a spear). Once the danger has passed, the body goes back to business as usual.

Chronic stress, on the other hand, happens when the body is constantly responding to stress and remaining in a heightened state for a long time. It can really do damage to the body over time.

Today, we’re going to talk about both of these types of stress—the classic fight-or-flight response as well as what happens when your body experiences persistent stress.

(Video) 2-Minute Neuroscience: HPA Axis

Meet the adrenal glands

When it comes to the body’s stress response, the adrenal glands are the stars of the show. My colleagues here at VB like to refer to these guys as “the party hats of the kidneys,” which is a pretty apt description considering their fun pointy shape and the fact that there’s one sitting atop each kidney. You might also know the adrenal glands as the suprarenal glands for this reason—suprarenal literally means “above the kidney."

Let's check out the adrenal glands in context in Human Anatomy Atlas:

The Endocrine System: The Adrenal Glands and the Stress Response (1)

Each adrenal gland has two main parts: an outer cortex, which makes up the majority of the gland, and an internal medulla. The cortex is composed of glandular epithelial tissue, whereas the medulla is made of nervous tissue.

Different regions of the cortex produce a variety of different hormones, including mineralocorticoids (which affect water and mineral balance), glucocorticoids (which affect glucose levels), and gonadocorticoids (adrenal sex hormones). Cortisol is a glucocorticoid released during the later part of the stress response.

The medulla produces epinephrine/adrenaline (E) and norepinephrine/noradrenaline (NE). Epinephrine is the principal hormone that interacts with the sympathetic nervous system in the initial part of the fight-or-flight response.

Fun fact: epinephrine and norepinephrine function both as hormones in the endocrine system and as neurotransmitters in the nervous system! In fact, norepinephrine is the main neurotransmitter of the sympathetic nervous system.

The acute stress response: playing hormone telephone

Now that you’ve gotten to know the adrenal glands a bit, let’s go step-by-step through the fight-or-flight response.

When your senses perceive a dangerous or threatening event, this triggers the amygdala—part of the limbic system involved in memory and emotion—to sound the first alarm. Basically, the amygdala presses the big, red “PANIC” button or, if you like thinking in terms of Lord of the Rings references like I do, lights the beacon at the top of the mountain that means “Gondor calls for aid!”.

The hypothalamus, a key player in the endocrine system, sees that beacon and musters the soldiers of Rohan to help—that is, it activates the sympathetic nervous system. This, in turn, signals the adrenal glands to secrete epinephrine and norepinephrine into the bloodstream.

The Endocrine System: The Adrenal Glands and the Stress Response (2)

Image from Human Anatomy Atlas.

The release of epinephrine helps the body respond to danger in a number of ways. The bronchioles in the lungs expand, and the rate of respiration increases, allowing for greater oxygen intake. The heart beats faster, causing a rise in pulse and blood pressure. All this is so that the muscles and the brain can get all the blood (and therefore oxygen) they need to function optimally.

(Video) Endocrine- Adrenal Stress Short term vs Long Term Stress-how stress kills

Other physiological changes that occur during the fight-or-flight response are dilation of the pupils and increased tension in the muscles as they prepare to move. Digestion and reproductive functions are suppressed.

The Endocrine System: The Adrenal Glands and the Stress Response (3)Microanatomy view of a terminal bronchiole from Human Anatomy Atlas.

Need a good way to remember epinephrine’s role in the stress response? Think about what an EpiPen (a shot of epinephrine) does to counteract a severe allergic reaction. While anaphylaxis constricts airways and lowers blood pressure, epinephrine from the EpiPen relaxes muscles in the airways, helping them to expand, and constricts the blood vessels, boosting blood pressure. It also increases heart rate and blood flow to the heart.

Ok, back to the short-term stress response. If the perceived threat remains beyond that first rush of epinephrine, a system called the HPA axis will kick in to help the body stay alert and ready for action. HPA is a super helpful acronym—it not only represents the hypothalamus, pituitary, and adrenal glands, but it also does so in the correct order.

The hypothalamus kicks off this part of the stress response by releasing a hormone called CRH (corticotropin-releasing hormone). This hormone signals the pituitary gland to release another hormone called ACTH (adrenocorticotropic hormone).

The Endocrine System: The Adrenal Glands and the Stress Response (4)

The hypothalamus secretes CRH, and the anterior pituitary gland secretes ACTH.Image from Human Anatomy Atlas.

ACTH travels through the bloodstream from the pituitary gland and signals the adrenal glands to release cortisol, which you might know as “the stress hormone.” Cortisol helps give the body the energy it needs to stay on high alert for a bit longer by signaling several organs in the body to make changes impacting blood glucose levels.

When cortisol levels are high, the liver will increase gluconeogenesis, the production of glucose from stored glycogen. Similarly, adipose tissue will respond to high cortisol levels by increasing lipolysis, the breakdown of fats into glycerol and fatty acids. Increased cortisol causes the pancreas to decrease insulin levels and increase glucagon.

The Endocrine System: The Adrenal Glands and the Stress Response (5)Posterior view of the adrenal glands, liver, and pancreas. Image from Human Anatomy Atlas.

Recovery

Let’s say you experience the fight-or-flight response while driving your car and you have to swerve suddenly to avoid an accident. You’ll most likely react in a split second, and you’ll feel that increase in pulse and respiration. Maybe your hands will be a little shaky as you continue driving. Now that the threat has passed, however, your body is free to calm down.

Recovering from an (everyday) acute stress response usually takes between 20 and 30 minutes. According to the general adaptation syndrome (GAS) model of stress responses, the period in which the body starts to wind down from a fight-or-flight response is called the resistance phase. Cortisol levels (hopefully) drop, the sympathetic nervous system dials down its activity, and the parasympathetic can resume its “rest and digest” functions.

If the body is not able to recover, it will eventually become exhausted, leading to fatigue, depression, and anxiety. This is when stress can take on it’s most insidious form: chronic stress.

(Video) Endocrinology - Adrenal Gland Hormones

The dangers of chronic stress

Chronic stress happens when the body is constantly responding to stress and is not able to fully recover. Cortisol remains high even for long periods of time. High-pressure jobs, financial hardship, relationship troubles, and trauma are just a few sources of long-term stress that can have harmful psychological and physiological effects.

Continuous fight-or-flight responses and HPA activity are rough on the body. Chronic stress can increase the risk of a number of health conditions including, but not limited to:

  • Heart disease
  • Lung disease
  • Cirrhosis of the liver
  • Cancer
  • Diabetes
  • Depression
  • Anxiety
  • Obesity
  • Hyperthyroidism
  • Ulcers
  • Sexual dysfunction

You also may have heard of a recent study by Zhang et al. confirming that stress can actually make your hair turn prematurely grey. Well, it’s true! It turns out that the norepinephrine, used as a neurotransmitter by the sympathetic nervous system’s response to stress, depletes a population of skin cells called melanocyte stem cells (MeSCs). MeSCs generate new melanocytes, the cells responsible for giving hair its pigment.

(Want to read more about hair growth? Read our blog post on hair here!)

Zhang et al. found that because of a certain receptor on the outside of the MeSCs, norepinephrine causes all the MeSCs in a given hair follicle to differentiate into melanocytes all at once. The next time a hair grows from that follicle, there won’t be any melanocytes to give it pigment because there are no MeSCs left to generate new melanocytes.

The Endocrine System: The Adrenal Glands and the Stress Response (6)Hair follicle (highlighted). Image from Human Anatomy Atlas.

In a review of the Zhang et al. study, Clark & Deppmann suggested that norepinephrine from the sympathetic nervous system’s stress response could affect other populations of stem cells in a similar way. That’s definitely a cool avenue for further research!

Adrenal gland disorders

There is a variety of different adrenal gland disorders, depending on the over or underproduction of hormones in the adrenal glands. For now, we’ll focus on cortisol, since it’s important to the body’s stress response.

Cushing syndrome happens when there is too much cortisol in the body. There are two types of Cushing syndrome: exogenous and endogenous. Exogenous Cushing syndrome is the result of high intake of corticosteroids from outside sources—usually medications such as prednisone or dexamethasone, which are used in the treatment of conditions like rheumatoid arthritis, lupus, IBD, and MS.

Endogenous Cushing syndrome is usually the result of an adrenal gland or pituitary gland tumor. An adrenal gland tumor will cause overproduction of cortisol directly, and a pituitary gland tumor will produce excess ACTH, which indirectly motivates overproduction of cortisol. (Remember, ACTH tells the adrenal glands to release cortisol into the bloodstream.)

Symptoms of Cushing syndrome can include weight gain and fatty deposits in the upper body, purple stretch marks on the abdomen, skin that easily bruises, growth of facial hair, muscle weakness, and bone loss. If left untreated, Cushing syndrome can lead to osteoporosis, hypertension, and diabetes.

If the cause of Cushing syndrome is a tumor, surgery is usually the first treatment method used. Radiation treatment, as well as medication to control cortisol production, may also be necessary.

Addison’s disease, also called primary adrenal insufficiency, is the “opposite” of Cushing syndrome—it is an autoimmune disorder in which the adrenal glands don’t produce enough cortisol (and they often also don’t produce enough of a hormone called aldosterone, which acts in the kidneys to regulate sodium and potassium levels in the blood). In cases of Addison’s disease, the immune system attacks the cortex of the adrenal glands, damaging them over time.

(Video) Stress response physiology

The list of symptoms of Addison’s disease is long, but some notable symptoms include:

  • Abdominal pain
  • Craving salty foods
  • Dehydration
  • Hyperpigmentation of skin
  • Extreme fatigue
  • Low blood glucose
  • Low blood pressure
  • Nausea, vomiting, and diarrhea
  • Weight loss

Treatment for Addison’s disease usually involves the patient taking artificial versions of cortisol and aldosterone. If left untreated, Addison’s disease can result in acute adrenal failure, also known as an Addisonian crisis.

Secondary adrenal insufficiency is another condition in which the adrenal glands don’t produce sufficient cortisol because the pituitary gland doesn’t produce enough ACTH. According to the Mayo Clinic, common causes of secondary adrenal insufficiency are “benign pituitary tumors, inflammation and prior pituitary surgery.” The symptoms of and pharmaceutical treatment options for secondary adrenal insufficiency are similar to those of Addison’s disease.

A quick review

We just threw a lot of information at you, so let’s recap with a handy chart!

The key players in the body’s response to stress are as follows:

Amygdala

Sounds the alarm when the senses pick up signs of danger.

Sympathetic nervous system

Prepares the body to fight, flee, or freeze with the help of epinephrine by increasing heart rate and respiration rate.

Hypothalamus

Produces and releases CRH, which signals the pituitary gland to release ACTH.

Anterior pituitary gland

Produces and releases ACTH, which signals the adrenal glands to release cortisol.

Adrenal glands

Releases hormones key to the stress response.

  • Epinephrine (adrenaline) - Produced by the adrenal medulla. Works with the sympathetic nervous system to help the body respond to a threat.
  • Cortisol - Produced by the adrenal cortex. Signals organs to regulate blood glucose levels so the body can have the energy it needs to stay on high alert.

Also, remember that although the acute stress response is important to our survival, helping us react in time to get out of potentially life-threatening situations, experiencing chronic stress can have a detrimental effect on one’s health.

Want to learn more about the key structures and functions of the endocrine system? Check out our Endocrine System eBook!

The Endocrine System: The Adrenal Glands and the Stress Response (7)

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FAQs

How does the adrenal gland respond to stress? ›

Through a combination of nerve and hormonal signals, this system prompts your adrenal glands, located atop your kidneys, to release a surge of hormones, including adrenaline and cortisol. Adrenaline increases your heart rate, elevates your blood pressure and boosts energy supplies.

How does the endocrine system play a role in stress and stress responses? ›

During times of stress, the hypothalamus, a collection of nuclei that connects the brain and the endocrine system, signals the pituitary gland to produce a hormone, which in turn signals the adrenal glands, located above the kidneys, to increase the production of cortisol.

Which endocrine gland is involved in the stress response? ›

When it comes to the body's stress response, the adrenal glands are the stars of the show.

What are the 3 hormones that the adrenal glands release during a stress response? ›

These hormones can be categorized into two broad groups: Catecholamines: Catecholamines are a group of similar substances that your body releases into your blood in response to physical or emotional stress. The primary catecholamines are dopamine, adrenaline and noradrenaline.

What are the 3 stages of stress response? ›

[18] This syndrome is divided into the alarm reaction stage, resistance stage, and exhaustion stage. The alarm reaction stage refers to the initial symptoms of the body under acute stress and the "fight or flight" response.

Which two endocrine organs are involved in the stress response? ›

STRESS. The stress-response includes two endocrine responses (from the same endocrine gland - the adrenal). The adrenal cortex releases glucocorticoids (about 50 diffent related hormones); the adrenal merdulla releases epinephrine. These two endocrine responses comprise the two primary components of the stress response ...

Why is the release of hormones and its process important to stress response Brainly? ›

Explanation: In a stressful situation , hormones that are released in an individual's body cause better coping mechanisms, Due to these hormones, an individual is able to concentrate more on the situation. The individual also produces better skills for reacting to the situation and gaining strength.

What stimulates a stress response? ›

If the brain continues to perceive something as dangerous, the hypothalamus releases corticotropin-releasing hormone (CRH), which travels to the pituitary gland, triggering the release of adrenocorticotropic hormone (ACTH). This hormone travels to the adrenal glands, prompting them to release cortisol.

What hormone is released by the sympathetic nervous system when the body is under stress? ›

Adrenaline is released mainly through the activation of nerves connected to the adrenal glands, which trigger the secretion of adrenaline and thus increase the levels of adrenaline in the blood. This process happens relatively quickly, within minutes of the stressful event being encountered.

What is the stress response system? ›

The stress response, or “fight or flight” response is the emergency reaction system of the body. It is there to keep you safe in emergencies. The stress response includes physical and thought responses to your perception of various situations.

What happens to the body during stress? ›

Your heart pounds faster, muscles tighten, blood pressure rises, breath quickens, and your senses become sharper. These physical changes increase your strength and stamina, speed up your reaction time, and enhance your focus—preparing you to either fight or flee from the danger at hand.

What do adrenal glands do for your body? ›

Adrenal glands, also known as suprarenal glands, are small, triangular-shaped glands located on top of both kidneys. Adrenal glands produce hormones that help regulate your metabolism, immune system, blood pressure, response to stress and other essential functions.

What happens when adrenaline is released? ›

Adrenaline helps your body react more quickly. It makes the heart beat faster, increases blood flow to the brain and muscles, and stimulates the body to make sugar to use for fuel. When adrenaline is released suddenly, it's often referred to as an adrenaline rush.

What hormones are released by the adrenal gland? ›

The adrenal cortex produces several hormones. The most important are aldosterone (a mineralocorticoid), cortisol (a glucocorticoid), and androgens and estrogen (sex hormones). Aldosterone helps the kidneys control the amount of salt in the blood and tissues of the body.

How does our body respond when adrenaline is secreted into the blood? ›

Response of body to adrenaline secretion: It causes the coronary heart to beat quicker subsequently offering extra oxygen to the muscle groups. Blood strain receives extended subsequently permitting extra glucose to go into the frame to offer energy.

How do you control stress response? ›

Stress management approaches include:
  1. Learning skills such as problem-solving, prioritizing tasks and time management.
  2. Enhancing your ability to cope with adversity. ...
  3. Practicing relaxation techniques such as deep breathing, yoga, meditation, tai chi, exercise and prayer.
  4. Improving your personal relationships.
5 Oct 2021

Which of the following happens during a stress response? ›

When stress happens, it makes more of the hormone ACTH. This hormone tells your adrenal glands to make more of their stress hormones. These stress hormones help you to focus, speed up your reaction time, and boost your strength. Your hypothalamus also helps your body respond to stress.

What is first stage of stress? ›

1. Alarm reaction stage. The alarm reaction stage refers to the initial symptoms the body experiences when under stress. You may be familiar with the “fight-or-flight” response, which is a physiological response to stress.

Can you live without an adrenal gland? ›

Humans cannot live without adrenal glands, so if both adrenal glands are removed (very rarely necessary), then the patient needs to take medications and supplements to provide the necessary hormones.

Which of the following hormones is part of the rapid response to stress? ›

Adrenaline is produced in the medulla in the adrenal glands as well as some of the central nervous system's neurons. Within a couple of minutes during a stressful situation, adrenaline is quickly released into the blood, sending impulses to organs to create a specific response.

How do you activate your adrenal glands? ›

7 Steps to Improve Adrenal Function
  1. Get lab work done. ...
  2. Make sleep a priority. ...
  3. Focus on low-intensity and restorative exercise. ...
  4. Increase your protein and fat intake. ...
  5. Supplement strategically. ...
  6. Cut out caffeine. ...
  7. Purposefully manage your stress levels.

How does stress affect hormones in the body? ›

Stress hormones cause your blood vessels to constrict and divert more oxygen to your muscles so you'll have more strength to take action. But this also raises your blood pressure. As a result, frequent or chronic stress will make your heart work too hard for too long.

Which hormone is responsible for fight or flight response? ›

As part of the response, the adrenal glands release hormones including adrenaline, norepinephrine, and cortisol, which triggers the cascade of physiological responses, including an increase in temperature, heart rate, respiration rate, blood pressure, and energy expenditure.

Which of the following is not stimulated by cortisol during stress? ›

Answer and Explanation: (b) Glucose uptake into muscle cells is not stimulated by cortisol during stress.

What triggers the adrenal glands to produce cortisol? ›

The hypothalamus produces corticotropin-releasing hormone (CRH) that stimulates the pituitary gland to secrete adrenocorticotropin hormone (ACTH). ACTH then stimulates the adrenal glands to make and release cortisol hormones into the blood.

Which gland is responsible for fight or flight response? ›

After the amygdala sends a distress signal, the hypothalamus activates the sympathetic nervous system by sending signals through the autonomic nerves to the adrenal glands. These glands respond by pumping the hormone epinephrine (also known as adrenaline) into the bloodstream.

How does the adrenal gland affect behavior? ›

Adrenal Glands and Psychology

The fight or flight phenomenon, in which a person's body rapidly prepares them to fight or flee a threatening situation, is controlled largely by the adrenal glands. During times of immense stress, these glands release adrenaline.

What are the stress responses? ›

Increased heart rate and respirations. Increased blood pressure. Upset stomach, nausea, diarrhea. Increased or decreased appetite which may be accompanied by weight loss or gain. Sweating or chills.

What happens when your adrenal glands stop working? ›

With adrenal insufficiency, the inability to increase cortisol production with stress can lead to an addisonian crisis. An addisonian crisis is a life-threatening situation that results in low blood pressure, low blood levels of sugar and high blood levels of potassium. You will need immediate medical care.

How do you regulate your adrenal glands? ›

The suggested treatments for healthy adrenal function are a diet low in sugar, caffeine, and junk food, and “targeted nutritional supplementation” that includes vitamins and minerals: Vitamins B5, B6, and B12. Vitamin C. Magnesium.

What is the anger hormone called? ›

Recognizing anger

Anger causes a physical reaction in the body. It releases adrenaline, the “fight-or-flight” hormone that prepares a person for conflict or danger. This can have the following effects: a rapid heartbeat.

What happens to your body when you are stressed? ›

Your heart pounds faster, muscles tighten, blood pressure rises, breath quickens, and your senses become sharper. These physical changes increase your strength and stamina, speed up your reaction time, and enhance your focus—preparing you to either fight or flee from the danger at hand.

Which part of the nervous system is responsible for triggering the release of stress hormones? ›

Briefly, in response to a stress, the brain region known as the hypothalamus releases corticotropin-releasing hormone (CRH). In turn, CRH acts on the pituitary gland, just beneath the brain, triggering the release of another hormone, adrenocorticotropin (ACTH) into the bloodstream.

What part of the brain controls stress and anxiety? ›

The amygdala, located deep inside the brain, is part of the emotional brain. According to this theory, we only feel anxiety when signals from the emotional brain overpower the cognitive brain, and into our consciousness.

Can your adrenal glands cause anxiety? ›

Symptoms include high blood pressure, fatigue and low levels of potassium. Pheochromocytoma: Caused by rare, non-cancerous tumors in the adrenal glands, this condition can cause panic attacks and anxiety, high blood pressure, heart palpitations and shortness of breath.

What is the function of adrenaline hormone? ›

Adrenaline triggers the body's fight-or-flight response. This reaction causes air passages to dilate to provide the muscles with the oxygen they need to either fight danger or flee. Adrenaline also triggers the blood vessels to contract to re-direct blood toward major muscle groups, including the heart and lungs.

What is the adrenal gland and what does it do? ›

A small gland that makes steroid hormones, adrenaline, and noradrenaline. These hormones help control heart rate, blood pressure, and other important body functions. There are two adrenal glands, one on top of each kidney.

How do you control stress response? ›

Stress management approaches include:
  1. Learning skills such as problem-solving, prioritizing tasks and time management.
  2. Enhancing your ability to cope with adversity. ...
  3. Practicing relaxation techniques such as deep breathing, yoga, meditation, tai chi, exercise and prayer.
  4. Improving your personal relationships.
5 Oct 2021

How do you improve your stress response? ›

Here are 15 evidence-based ways to relieve stress.
  1. Get more physical activity. ...
  2. Follow a healthy diet. ...
  3. Minimize phone use and screen time. ...
  4. Consider supplements. ...
  5. Practice self-care. ...
  6. Reduce your caffeine intake. ...
  7. Spend time with friends and family. ...
  8. Create boundaries and learn to say no.

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