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The Axis: How Stress Works

Updated: Jan 18, 2023

The Axis: How Stress Works Generally speaking, the more I understand something the more I appreciate it. Sometimes it is not enough to just know THAT something happens. I want to know WHY and I want to know HOW. In this article, we'll take a deep look at what is happening on a physiological level when our bodies ramp into a stress response. By putting your mind in your molecules, you’ll understanding the mechanisms in action, gaining insight into the “whys” and “hows” of your own processes. Let’s break down some vocabulary before we get started:

Stressor: A disturbance to the system. Consider applying the bio/psycho/social model --------------->

Stress response: Specific changes produced by the disturbance Stress: Nonspecific reaction to the state of change Eustress: energizing and generally positive, motivating but not debilitating Distress: exhaustive and generally negative, debilitating and outside of coping range

In the presence of a stressor a chain of reactions occur. It all starts in the limbic system in your brain, your emotional and behavioral center. Some parts of the limbic system pick up on sensory information, some parts translate that sensory information into feeling, other parts translate that feeling into behavior and other parts translate that sequence of events into memories. The limbic system is composed of 4 structures: thalamus, hypothalamus, hippocampus and amygdala.


One small structure in the limbic system, deep in the pockets of the brain, the amygdala, first picks up on the presence of a stressor. When the amygdala lights up with fear, it pings another limbic structure sitting just nearby--the hypothalamus. The hypothalamus translates that amygdal information into action. It has control over the autonomic nervous system, which contains the spectrum of states between sympathetic (fight or flight) and parasympathetic (rest and digest).

When the hypothalamus receives that "ping" from the amygdala, it translates information into action responding electrically first and chemically second. Through electrical signaling, the hypothalamus stimulates sympathetic neurons, communicating to the nervous system that it's time for action. The sympathetic neurons have a direct effect on the adrenal glands, which live just above the kidneys.

The adrenals respond to this electric, sympathetic tickle by releasing epinephrine and norepinephrine. These substances are synonymous with adrenaline and noradrenaline, two chemicals that act both as hormones and neurotransmitters. The release of these substances create the first wave of the stress response - faster heart rate, faster breathing, changes in blood distribution and increased blood sugar levels.

So that's how the body responds electrically first. Let's take it back to the brain and see how the hypothalamus reacts chemically.

About 10 seconds after this wave hits, the hypothalamus initiates the cascade of the second wave of our stress response in the form of chemical signaling. It releases corticotropin releasing hormone (CRH), which signals the anterior pituitary gland, dangling just below, to release adrenocorticotropic hormone (ACTH), which travels to the adrenal glands through the blood. The adrenals are signaled to produce their second contribution to the stress response, cortisol. While adrenaline and noradrenaline are the initial "revvers of the stress engine", cortisol is what keeps it going and maintains the stress response, and ultimately the state of stress.

This relationship between hypothalamus, pituitary and adrenals is called the HPA Axis

Cortisol release feels like an energy surge. Similar to adrenaline and noradrenaline, cortisol works to increase heart rate, blood pressure and general cardiac output. It also increases access to “fast fuel” by mobilizing fatty acids and telling the liver to increase blood glucose, both through breakdown of glycogen (stored glucose) and gluconeogenesis, the process of breaking down amino acids to make glucose. Cortisol can prepare us to deal with whatever stressor we are facing by making us feel super attentive, aggressive and motivated. It can also paralyze us and make us tremble with fear. Depends on the stressor and depends on the person.

At the same time that we become these fight or flight machines, cortisol dampens the pieces of ourselves deemed unnecessary for immediate survival, like libido, appetite and immune function.

Once there is a surge of cortisol in the blood stream, the hypothalamus detects high levels and stops creating the CRH, in turn shutting down the whole wave of the stress response. This is called a “negative feedback loop”: when the result of a process shuts down the process itself.

This whole systemic reaction is absolutely necessary for our survival as a species. In a healthy HPA axis, there is only activation when necessary, and cortisol levels in the blood are naturally higher in the morning and fall throughout the day. Malfunctions occur when this system gets out of wack. If sympathetic fibers of the nervous system are constantly on line, the system gets overrun with cortisol, which means blood glucose levels constantly soar, ultimately getting stored as fat. The heart gets worn out, the immune system suppressed, appetite and libido go out the window or through the roof. All sorts of problems start to occur when this system goes haywire. This can happen if someone is constantly exposed to stressors, if they perceive a majority of their life as stressful or if they do not have techniques that can drop the body out of the sympathetic "fight or flight" state and back down into a parasympathetic "rest and digest" state. '

We can learn to adapt our stress responses in a several ways:

1) Buffering: Decreasing exposure to, or eliminating, the stressor. Easier said than done? Sure. Possible? Absolutely. This can be done by examining your circumstances and behavior and how they contribute to your physical state of stress (like heart rate sky rocketing, palms getting sweaty, the mind racing). If a component of your life is obviously contributing to this state and can easily be adjusted or removed, consider advocating for your HPA axis and making small, attainable changes.

2) Shifting the mindset: Sometimes stressors cannot be removed, and we simply have to exist with them and navigate how to live our best life in the presence of something undesirable. We can do this with things that help us shift into a more parasympathetic "rest and digest" state (opposite of sympathetic) which will temporarily shut off the mechanisms that initiate the whole stress response in the first place. Meditation and yoga are a few obvious activities that can help us achieve that state of relaxation (click here for a free 20 minute guided meditation), but things like drawing, reading, painting, cooking, hanging with loved ones, getting a massage, being in nature, being in flow can also help us shift into this calmer state of the nervous system.

3) Impose eustress: Eustress poses a challenge rather than a threat. Things like exercise, saunas, cold exposure, sex and some breathing exercises actually trigger the stress response, sending a blast of cortisol out into the blood stream. Intentionally exposing ourselves to this not only allows the body to metabolize cortisol and teach the body to become better at managing the cycles of the stress response, but also gives you the opportunity to feel that state, and then feel the end of it. That mental preparation works wonders in our physical body, mental state and energetic wellbeing.

Understanding the transience of the stress response can give us discernment in situations of distress and use the stress response to work in our favor and guide us toward action, rather than continuing indefinitely and wreaking havoc on our systems.

There is a power in getting acquainted with the inner workings of our body. Observing how our environment effects us, on both a conscious and microscopic level, impacts the way we interact with our surroundings and with ourselves. Knowing our stressors, how they effects us and what to do about it gives us the capacity to live a fuller and more intentional life.

Understanding how life’s pieces work makes it that much more beautiful. Thanks for reading, D References:

“The HPA-Immune Axis and the Immunomodulatory Actions of Glucocorticoids in the Brain” Bellavance, M.A., Rivest, S. “A Biopsychosocial Model Based on Negative Feedback and Control. Carey, T.A., Mansell, W., Tai, S.J. “Principles of Human Anatomy” Tortora, G.J., Nielsen, M.T. "Homeostatic Systems, Biocybernetics and Autonomic Neuroscience" Goldstein, D., Kopin, I.

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