Tag Archives: stress

Our Nervous System, explained

I am taking the online course Being Well in a Digital Age – The Science and Practice of Yoga, which partially explains why it has been two years since my last post on this blog. During the first half of 2016 I was studying for my 200-hour yoga teacher certification and blogging at my other web home, Yoga ~ Dance ~ Music ~ Movement. And for large portions of 2015, 2016, and the summer of 2017, my son, daughter-in-law and grandchildren were living with us. Spend time blogging here or with my family; easy decision!

My yoga blog has been the recipient of all yoga-related writing and below is a cross-post of my most recent post, written earlier today. It deals exclusively with the nervous system and how stress impacts and is dealt with by the nervous system. The post is reprinted below.


The lectures by Catherine Spann and Stacy Dockins from Being Well in a Digital Age – The Science and Practice of Yoga have explained the basics of what happens when stress manifests in the human body. A little bit of stress is manageable; a lot of stress begins to break down our capacity to effectively deal with the stress, and that in turn can manifest in the malfunctioning of other body systems.

Our nervous system consists of two parts, the central nervous system and the peripheral nervous system. I use the word “central” to help remember what the central nervous system consists of – it consists of our brain and spinal cord, the part of our nervous system that runs center or central in our body from our head to the bottom of the spine and is housed in our axial skeleton.

The peripheral nervous system is the communications conduit between the central nervous system and the rest of the body. The word “peripheral” means outlying items or those not centrally located. Again, this helps me remember what the peripheral nervous system deals with – the parts of our nervous system peripheral to the brain and spinal cord, the parts of our nervous system that run through our appendicular skeleton.

The peripheral nervous system consists of the somatic nervous system, which are our voluntary actions, and the autonomic nervous system, which are our unconscious actions such as our heart beating (though we can control that to some extent), and the regulation of digestion, respiration, to name a few of the systems.

Finally, the autonomic nervous system is further composed of the sympathetic nervous system and the parasympathetic nervous system. These two have alliterative words to quickly and easily describe their functions. The sympathetic nervous system triggers the fight, flight or freeze response, which Catherine likens to putting a lead foot on a gas pedal.  The parasympathetic nervous system invokes the rest and digest response, which Catherine equates to putting on the brakes. All of these systems interact with the hypothalamus in the brain, which along with the pituitary gland and the thalamus are part of the endocrine system.

The last piece of this puzzle is the vagus nerve, the longest nerve of the autonomic nervous system. Its role as part of the parasympathetic nervous system involves regulating the heart, lungs and digestive tract.

Now we come to stress and how it impacts our nervous system. Stress can be of a short duration, known as acute stress, or it can be chronic stress meaning it is ongoing over a long period of time or simply recurring over and over and over. Our nervous system has a “set point” where it is relatively in balance; this is called homeostasis. Each time our body undergoes some form of stress, our nervous system makes adjustments to return to homeostasis. This adjustment process is known as allostasis. If we are frequently engaged in allostasis it leads to allostatic load, which is the wear and tear on our body systems that often leads to an autonomic imbalance, meaning our sympathetic and parasympathetic nervous systems are out of whack.

Eventually allostatic load causes a cycle that over time makes it difficult to reset our nervous system and find our way back to homeostasis. This is where yoga comes in! Yoga can calm the nervous system and strengthen the ability to self-regulate. A calm nervous system can begin the process of allostasis and correcting for the growing internal imbalances.

One way of calming the nervous system is by stimulating the relaxation response as described by Dr Herbert Benson. Deep, slow breathing stimulates the vagus nerve, which then positively triggers the parasympathetic nervous system. As noted in a prior post, the combination of movement (the physical part of yoga), breath, mindful attention, and relaxation lead to improved mental health. This combination makes for a powerful self-regulation tool that lets you consciously partner with allostasis to reset your body in homeostasis.

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Commuting.

For this school year, I am commuting 62 miles each way to where I teach. That translates to an hour’s drive in the morning, and on the days of after school meetings, anywhere from 70 to 90 minutes for the drive home.

After 14 years of teaching just four miles from my home, and several times a year walking home from school, you can perhaps begin to imagine the impact this change of time spent sitting in a car has had on me – less time available for walking, poor air quality (though I recirculate the interior air while driving on I-95 so as to minimize the trucking fumes), muscle strain from sitting in one position, and stress from intense concentration so as to keep my drive safe.

The Hidden Toll of Traffic Jams, in the November 2011 Health & Wellness section of The Wall Street Journal, discusses the impact of traffic emissions on commuters, including this tidbit:

And older men and women long exposed to higher levels of traffic-related particles and ozone had memory and reasoning problems that effectively added five years to their mental age, other university researchers in Boston reported this year. The emissions may also heighten the risk of Alzheimer’s disease and speed the effects of Parkinson’s disease.

That last sentence is fascinating to me because my Dad commuted daily from New Hyde Park, NY to Hasbrouck Heights, NJ for upwards of 20 years. While his distance was half of my current commute, the time spent in the car was about equal due to the enormous volume of traffic crossing the George Washington Bridge.

And why is this fascinating? My Dad developed Alzheimer’s and Parkinson’s in his later years. To be sure, some of that was likely hard-wired into his DNA, but “heighten the risk” and “speed the effects” make me wonder about the commute’s impact. 

Bruce McEwen, in a March 2011 Dana Foundation article Effects of Stress on the Developing Brain, talks about the effects of stress on the brain and body. “Besides major life events, abuse and neglect, it is the ordinary day-to-day experiences in family, neighborhood, commuting and work, and school that affect brain and body function and promote those health damaging behaviors.

A recent acquaintance, who crafts infographics, sent me this infographic describing The Killer Commute. The graphic is provided by CollegeAtHome.com and it speaks volumes! She asked for my feedback, and this is what I had to say: 

The graphic is a killer! Okay, what I mean is, it depicts my experience – all the “yuck” parts of commuting. I had already determined to leave my job (and gave notice in January that I did not want another contract), but if I hadn’t already done that, the graphic would have convinced me to do so.
 
The parts covering health detriments are intense, (perhaps I can use them to drum up business for a “Yoga for Commuters” class….)
 
I only have two issues with an otherwise highly effective and convincing graphic – it is demoralizing! And the sources at the bottom were difficult for me to read.

Cortisol

Think about something you remember well. Most likely that something produced an emotional response in you. Be it positive or negative, the more intense your emotional response, the stronger your memory of that particular event. It turns out that memories encoded through emotions are the strongest of all our memories.

Cortisol gets released from the adrenal glands (located above the kidneys) in response to strong stimuli, especially if the stimuli causes you some stress, again either positive or negative. Research has shown that cortisol plays a role in memory and learning, although too much of it causes the opposite effect of not thinking or remembering clearly. When the brain perceives strong stress, cortisol partners with adrenaline to deal with fight or flight. A little bit of cortisol is helpful but too much of it can be detrimental.The Human Brain and Stress page at The Franklin Institute Science Museum contains informative explanations of the effects of noise on creating stress within the brain, and the impact of stress on memory and gender. About three-quarters along on the page you will find information about the role of Cortisol.