Summary of Human Stress Physiology

Stressed-Freaked out Emoji featured image

How Stress Physiology Compromises Your Life

The impact of negative stress on your body's function

This article discusses the physiological changes which occur in your body and brain because of the “fear and protection” reaction (historically called “fight or flight”)

The topic of Stress Physiology is critical both to the value of Optimal Life Health & Wellness Coaching AND to the potential impact of Optimal Life Chiropractic care.

Here, we explain the potential impact of ongoing physical, biochemical and mental-emotional stress-load on the human body.

Stress Level Meter Graphic

In conjunction with the ‘rationale’ for regular chiropractic care, this article describes some of the underpinning value to the human ‘ecosystem’ of progressively identifying, understanding and then working toward reducing stress-load for human health and wellbeing.

“It must be emphasised that ALL of these physiological changes are absolutely necessary, exceptionally ‘intelligent’ responses to maximise survival in a stressful environment!

Without them, you would die!

But they are designed to be immediate, short-term responses, not something that is occurring on an ongoing basis, all of the time.”
Headshot - Dr James Chestnut
Dr James L. Chestnut

This summary is provided primarily from resources produced by Dr James L. Chestnut B.Ed., M.Sc., D.C., C.C.W.P.  – Many thanks for these works!

Topic One: The Human Ability to Initiate or Depress Stress Physiology

There is a well-developed scientific field called PSYCHO- (of our psychology) NEURO- (brain & nerves) IMMUNOLOGY (immune system).

Scientists studying and researching in this field explore the interplay, relationship and control of the body and mind (‘the human ‘ecosystem’) via the nervous system and immune system (now considered a ‘mobile’ nervous system) and our conscious awareness.

We are all know that we can begin to feel stressed OR make a stressful experience worse, by thinking about, dwelling on, or remembering past or upcoming stressful events/circumstances.

Now it’s been proven that we can do the opposite as well - we can make the conscious choice to react differently to potentially stressful stimuli and therefore reduce our stress!

Stress Ball Infographic with different characteristics

The stress-inhibition/logical thought pathway operates from the left ‘prefrontal’ area of the brain and can ‘turn off’ or ‘dial down’ the stress and anxiety brain controller (amygdala) with special brain-chemicals (GABA).

This is MUCH HARDER to do if we are under long-term stress – it is easier for us to dwell on the negative. In this situation, the glass DOES always seem half empty. We are more sensitive and over-reactive.

All because these pathways are the ACTIVE and REINFORCED brain-nerve pathways (amygdala-locus ceruleus-right prefrontal cortex).​

Our brain is constantly changing – de-wiring and re-wiring in response to our lives. This is called neuroplasticity. 

If the long-term stress pathways are always on, they grow and become stronger!

The only way to beat this, and stop the brain automatically responding in a ‘stressed’ way is to start ‘firing’ and then ‘growing’ (neuroplastic again) the non-stressed, healthy pathways.

This is either done consciously from the LEFT brain (above) and/or via movement signals to a special part of the brain (cerebellum), which also then dials down the amygdala.

Remember this is a conscious process we can choose to create in our lives…

Topic Two: The FEAR & PROTECTION reaction - the Beginning of Stress Physiology

Let’s now look into the subconscious or unconscious brain and body responses to negative (dis-) stress – what Chestnut has termed SOMATO- (of the body) NEUROIMMUNOLOGY™. 

This is primarily an automatic reaction and is rarely brought to conscious awareness.

If the reaction at this level of the brain is the negative, chronic stress response, once again, these will be the pathways that grow strong and dominate how your brain will react!

What is needed is a way to ‘program’, ‘fire’ and ‘grow’ the unconscious positive brain 'dial-down' of the stress and anxiety centre of the brain – and this is where spinal adjustments (and other movement, particularly ‘backward’ movements of the trunk) can be extraordinarily helpful.

This stress/anxiety centre (the amygdala) is ‘down-regulated by these movement signals processed through a special part of the brain (cerebellum).

Unfortunately commonly-used drugs (like anti-depressants) serve only to ‘de-wire’ or desensitise these natural nerve pathways, causing further problems.

Overcoming Stress feature image

The GREAT thing is that both the conscious and sub-conscious can affect each other back and forth, so conscious stress-reduction strategies + adjustments/movement will build upon each other for an even better result!

Step 1: The first step in any reaction to stress is that FIRST, your body has to DETECT it...

Of course this happens through the nervous system – signals that indicate actual or possible threat or stress in the environment (including the environment inside your body!) are sent toward to your spinal cord and then on to your brain.

A stressor is any stimulus (be it physical, chemical or mental-emotional) that signals to the body some form of toxicity (body doesn’t like it) or deficiency (body needs it, but isn’t getting it).

Step 2: The ALARM reaction - "to urgently change the environmental stress load, NOW"

The ALARM reaction is a reflex and is pretty much automatic.

The ‘stress’ signals ‘land’ in an area of the (sympathetic) nervous system (cell bodies of intermediolateral tract (IML)) and cause them to ‘fire’

The ALARM reaction is the typical “fear and protection” reaction – or what was commonly called ‘fight or flight’ in the past.

“you don’t need anabolism (cell growth) for survival while you're being attacked by a tiger”

The Primary Effects include:

This list is not exhaustive, but describes some examples:

  • DECREASES anabolism (growth and repair) – sex glands, sex drive, digestion, growth (growth hormone production), cellular immunity – it’s a waste of energy and resources
  • INCREASES catabolism (body breakdown) to provide resources for emergency response
  • INCREASES Heart Rate, Stroke Volume (and therefore Blood Pressure)
  • INCREASES Blood Sugar
  • PRIORITISATION of blood flow to areas of the body needed for fight/flight (fear and protection) responses, and
  • DECREASED blood flow to areas for healing, growth, repair (relaxation and exploration)
  • DECREASES cellular immunity – uses too much energy = waste!
    Activated later for healing, growth, repair

This is an incredibly fast outcome, because unlike MOST nerve pathways, there is no relay-chain of two linked nerve cells to get the message through.

The adrenal glands are the source of the two primary ‘stress’ hormones – cortisol and adrenaline.

This is the slower and more sustained pathway that continues the release of stress hormones.

It occurs through releasing hormones from the brain that act on the adrenals  (via the H-P-A axis)

Centripetal fat storage means hips, tummy and thighs.

This type of fat is not just a place for storage – it is also metabolically active and releases hormones which perpetuate the problem.

This fat storage has increased association with diabetes, heart disease, virtually every other chronic illness including cancer.

The stress response, by activating threat and anxiety brains systems (and sympathetic system) DECREASES the ability to sleep.

A DECREASE in SLEEP = an INCREASE in release of Stress Hormones!! (and vice versa)

Shortening even one night’s sleep by 4 hrs = a significant increase of stress hormone release
DECREASES insulin receptor sensitivity

Topic Three: Effects of Stress Physiology Hormones

The two primary stress hormones – a class of hormones called ‘catecholamines’ (adrenaline) and a class of hormones called ‘glucocorticoids’ (cortisol) are primarily released from the Adrenal Glands…

CATECHOLAMINES - The major one being ADRENALINE

The following is a list of all of the physiological effects of releasing catecholamines into the body as part of the ‘Fear & Protection’ reaction:

Stressed Man trying to remember everything

This occurs through epigenetic down-regulation – the cells literally remove these receptors from their membranes to ‘deafen’ themselves from the excessive quantities of Insulin in the blood.

This occurs in almost all body cells, particularly the liver. Muscle cells are a rare exception.

[Cortisol (next topic) also adds to this effect]

  • THIS LEADS TO INSULIN RESISTANCE

Adrenaline increases both heart-rate (beats per minute) and stroke volume (quantity per beat)

Combined with another effect, the increase of blood vessel constriction on the ‘orders’ of the sympathetic nervous system – 

  • THIS INCREASES BLOOD PRESSURE

** The ‘intelligent’ reason for this, is that it enables rapid delivery of stress hormones and energy substrates

Some areas of the body respond to Adrenaline by constricting (reducing flow of blood to these ares), others by dilation (allowing more blood to these areas)

This also contributes to – 

  • INCREASED BLOOD PRESSURE
  • POSSIBLE INCREASE IN BLOOD VESSEL INFLAMMATION (more plaque formation), and
  • EFFECTIVE ‘SHUTTING DOWN’ OF LESS VITAL BODY FUNCTIONS while under stress

 

This makes the blood more “sticky”, it – 

  • THICKENS THE BLOOD

Thicker blood can cause clots which can reduce or block blood flow

** The ‘intelligent’ reason for this, is that it prepares the body for wound-repair – in case a trauma is sustained.

Fat is released from selected fat stores around the body (while being stored at the same time around tummy, hips and thighs)

  • THIS INCREASES FAT CONTENT OF THE BLOOD – total triglycerides and altered fractions/types of cholesterol carrier-molecules.

** The ‘intelligent’ reason for this, is so that it can be used for gluconeogenesis (to make glucose for energy)

This causes chronic changes to cognition, literally – your ability to THINK.

  • INHIBITS FACTUAL LEARNING, 
  • INHIBITS WORKING MEMORY, and
  • INHIBITS THE ABILITY TO FOCUS ATTENTION UNDER CHRONIC STRESS

** These pathways also become sensitized with chronic stress

 

“Cells in hippocampus actually shrink, and can die”

Stimulation from appropriate levels of movement (including the improved movement resulting from chiropractic adjustments) can theoretically increase both the size and number of hippocampus cells – directly increasing and/or helping restorea:

  • Your ability to LEARN
  • Your ability to REMEMBER

This could theoretically significantly decrease (up to 70%) incidence of Parkinson’s /Dementia

The amygdala is the stress/anxiety centre of brain.

The amygdala being stimulated leads to:

  • PUTTING YOU INTO A STATE OF ALARM TO MAXIMISE YOUR CHANCE OF SURVIVAL
  • EMOTIONAL / ANXIOUS MEMORIES DOMINATE – “remember next time to LOOK for the tiger”

** These pathways also become sensitized with chronic stress

Releases corticotrophin releasing hormone (CRH), in turn activating Locus Ceruleus area of the brain:

The release of noradrenalin had wide impacts on brain function:

  • ACTS ON THE EMOTIONAL/LEARNING CENTRES OF THE BRAIN
  • DECREASES LOGICAL BEHAVIOUR
  • DECREASES SHORT-TERM MEMORY
  • DECREASES CONCENTRATION

** you are more easily distracted / you cannot focus your attention very well

  • INCREASES EMOTIONAL LEARNING
  • INCREASES INSTINCTUAL BEHAVIOURS
    INCREASES SENSITIVITY (SENSITIZATION) OF SENSORY NERVE SYSTEMS

** increases your sensitivity or perception of pain

“This sharpens the signal detection mechanism at expense of concentration = you become ‘twitchy but forgetful'”

  • YOU BECOME BOTH TWITCHY AND IRRITABLE

“Your brain is searching for an escape route instead of for answers”

** These pathways also become sensitized with chronic stress

This initiates the Hypothalamus-Pituaitary-Adrenal (H-P-A) Axis to
  • MAINTAIN THE STRESS REACTION / ADRENAL REACTION

Under NORMAL circumstances the hypothalamus is INHIBITED by the brain’s ‘feel good’ chemical: SEROTONIN – this is used by the brain to ‘get us back in balance’ after we’ve fired off the stress pathways.

 

** These pathways also become sensitized with chronic stress

Under Chronic Stress, serotonin production cannot keep up, which leads to:

Any serotonin that is made, is being used for anti-anxiety functions and none is left for the NORMAL job of seratonin: ‘feeling good’

  • THIS LEADS TO DEPRESSION

In combination with the effects of increased noradrenaline being released from the Locus Ceruleus (described above), decreased serotonin contributes to the following effects:

  • DEPRESSION
  • IRRITABILITY
  • FATIGUE
  • LISTLESSNESS
  • SLEEP PROBLEMS
  • TENSION HEADACHE
  • DECREASED SEX DRIVE
  • DECREASED GROWTH HORMONE – more rapid ageing
  • CHANGES IN APPETITE – craving sugar and fat^
  • WEIGHT-GAIN

^Fat and sugar are the main components of (building blocks needed to produce) stress hormones.

Stressed man with brain exploding

GLUCOCORTICOIDS - The major one being CORTISOL

The following is a list of the MAJOR physiological effects of releasing catecholamines into the body as part of the ‘Fear & Protection’ reaction:

Cortisol is particularly involved with reduction of (cell-mediated) immune function

**The intelligent reason for this is that such function is “metabolically expensive” meaning it takes TOO much energy. These functions are turned off “while you’re running from the tiger” – it is only when you survive the tiger that the body then prioritises ‘healing’ functions in the event you managed to get ‘bitten’

As mentioned in the previous section, in conjunction with catecholamines, cortisol reduces insulin receptors on cell membranes (excluding skeletal muscle).

Acts on the liver, causing breakdown (CATABOLISM) of sugar-stores (glycogen).

** This is made worse because the liver quickly becomes insulin-resistant

  • INCREASES BLOOD SUGAR LEVELS

Acts on liver, causing breakdown (CATABOLISM) of protein stores for gluconeogenesis (turning protein into sugar for immediate energy needs)

  • STRUCTURAL PROTEIN DEGRADATION – breakdown of muscle, tendons, ligaments etc.

Acts on the liver to release fat stores and also changes the ratios of LDL vs HDL being produced.

  • THIS INCREASES FAT CONTENT OF THE BLOOD – total triglycerides and altered fractions/types of cholesterol carrier-molecules.

** The ‘intelligent’ reason for this, is so that it can be used for gluconeogenesis (to make glucose for energy). LDL, the so-called ‘bad’ cholesterol is released because it is kind of like a ‘band-aid’ plug to protect from the effects of increased blood pressure.

The NET effects of these two changes is

  • DECREASED HDL production, and
  • DECREASED LDL absorption/uptake by the liver

** More LDL provides more building blocks (easily accessible, less ‘densely packed’ cholesterol) for continued steroid-based hormone production; 

** More LDL serves a function in wound-healing (clotting and repair) so more LDL prepares for this potential need

** More LDL is necessary for mood regulation after the thread has ceased – it is used to REVERSE/COUNTERACT the blood sugar low after insulin does ‘overkill’

Insulin infographic featured image for article

Insulin Resistance – a Huge Problem!

Insulin resistance is a major ‘pillar’ of chronic ill-health. Read more about these ‘pillars’ here – it’s truly important information to understand. Body resistance to insulin comes about because of sustained high blood sugar levels/load that cause the pancreas to secrete large quantities of insulin. Normally one of the major effects of Insulin is lowering

Read More »
Red Blood Cells within an Artery

Effects of Long-term High Blood Sugar Levels

High blood sugar levels are a consistent health-risk for many of us – whether or not we are ‘officially’ diagnosed with diabetes or pre-diabetes. This comes about primarily as a result of the foods a lot of us in industrialised society choose to eat. These foods are mostly highly refined, non-fibre ‘foods’ containing refined sugars/corn

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Stress hormone effects word cloud featured image

Negative Health Effects of Chronically High Stress Hormones

In another article here, we describe the release of stress hormones as part of the body’s ‘fear & protection’ reaction. The question is, “what does that mean for how our bodies work?” The negative health effects of increased stress hormones being released on an ongoing basis are stark and far-reaching. Almost every current ‘disease of

Read More »

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