What is Dysautonomia?

Pyrrhus

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What is Dysautonomia?

For those who may be too afraid to ask, the word "dysautonomia" simply refers to any dysfunction of the autonomic nervous system.

The autonomic nervous system is the part of the body's nervous system that monitors and automatically controls the internal state of the body. In contrast, the "somatic nervous system" is the part of the body's nervous system that monitors and responds to the external environment.

For example, the autonomic nervous system receives input from sensory nerves that sense when there is food in the stomach and then activates motor nerves to push food through the digestive system.

Another example: the somatic nervous system receives input from the sensory nerves that convey vision from the eyes indicating that a big bear is approaching you and then activates motor nerves to make your legs run away from the bear.
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A very important thing to appreciate is that the autonomic nervous system is very large, and there are many many different types of things that can go wrong with it. Since any dysfunction of the autonomic nervous system is referred to as "dysautonomia", the word "dysautonomia" can therefore refer to many many different conditions:

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As you can see in the above diagram, the autonomic nervous system is anatomically divided into a "sympathetic" part and a "parasympathetic" part. The sympathetic part of the autonomic nervous system is often involved in "fight or flight" responses. In contrast, the parasympathetic part of the autonomic nervous system is often involved in "rest and digest" responses.

Hope this helps.
 
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Is the SNS and PNS working in a all or nothing fashion throughout the whole body, so if one of them is active then the other one is not active? Or can a SNS nerve going to one organ be active at the same time as a PNS nerve going to another organ is active.
 
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Pyrrhus

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Is the SNS and PNS working in a all or nothing fashion throughout the whole body, so if one of them is active then the other one is not active? Or can a SNS nerve going to one organ be active at the same time as a PNS nerve going to another organ is active.
Excellent question.

The division of the autonomic nervous system into "sympathetic" and "parasympathetic" parts is primarily an anatomical division, as the sympathetic signals travel mostly down the spinal cord and the parasympathetic signals travel mostly down non-spinal (cranial) nerves such as the vagus nerve.

In terms of how these two parts function, it is much more complicated. Yes, in the simplest situations, such as in a pure "fight or flight" response to external danger, sympathetic signals might be activated and parasympathetic signals might be suppressed.

But in most other situations, certain sympathetic signals might be activated at the same time as certain parasympathetic signals. For example, in the evolutionarily-programmed autonomic response to excessive heat, the autonomic nervous system might increase the blood flow to the skin to better dissipate heat from the body, which is an effect handled by parasympathetic signals. At the same time, the autonomic nervous system might increase the heart rate in order to pump more blood to the skin and dissipate heat faster, which is an effect handled by sympathetic signals.

So there are many autonomic responses that make use of both sympathetic and parasympathetic signals in order to best respond to the particular internal and external environment that the body finds itself in. Unfortunately, this fact is ignored by some writers who oversimplify situations and try to divide everything into "sympathetic" versus "parasympathetic".

I hope this clarifies.
 
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For some examples of the different types of dysautonomia in ME, see the following 7 discussions:

1) The best known type of dysautonomia in ME is orthostatic intolerance (OI). But how exactly is OI a dysfunction of the autonomic nervous system? A 2013 review shows that OI happens when autonomic nerves fail to constrict blood vessels upon standing!
https://forums.phoenixrising.me/thr...sels-low-blood-volume-and-baroreflexes.86445/

2) Do your fingers wrinkle in warm water? Did you know that this is controlled by the autonomic nervous system & isn't simply related to skin moisture? A lack of wrinkling therefore means dysautonomia!
https://forums.phoenixrising.me/thr...reening-test-before-tilt-table-testing.77607/

3) Some patients report dysautonomia of the pupils in their eyes, including unusual dilation in both eyes (mydriasis), in only one eye (anisocoria), or rhythmic contractions (hippus).
https://forums.phoenixrising.me/thr...upils-constricting-dilating-back-forth.82520/

4) ...and let's not forget Erectile Dysfunction...
https://forums.phoenixrising.me/threads/erectile-dysfunction-as-dysautonomia.86583/

5) Some studies suggest that Irritable Bowel Syndrome (IBS) might be a dysautonomia of the nerves that tell muscles to move food through the intestines. Too little stimulation: IBS-C. Too much: IBS-D!
https://forums.phoenixrising.me/threads/irritable-bowel-syndrome-ibs-summary-of-discussions.84970/

6) Did you know that there are actually 4 types of gastrointestinal (GI) reflux dysautonomia, which occur when the autonomic nervous system fails to close a GI valve, leading to improper food movement!
https://forums.phoenixrising.me/threads/gastrointestinal-reflux-as-dysautonomia.86644/

7) The vagus nerve tells the pancreas to release digestive enzymes into the intestines after you eat, which help to absorb nutrients. Can dysautonomia of the vagus nerve therefore lead to malnutrition?
https://forums.phoenixrising.me/thr...y-epi-and-chronic-fatigue-syndrome-cfs.62997/