The human body controls many of its most basic functions by utilizing a specialized part of the nervous system that works almost entirely on its own, that is with little or no conscious ability to control its function. When exposed to stressful situations, the autonomic nervous system exerts some level of control over almost all bodily functions. Sometimes however, overactive function in one part of the autonomic nervous system can lead to profoundly negative effects on the person.
More than One Nervous System?
All higher organisms have more than one nervous system. How can that be? Conscious control of certain bodily functions or behaviors is the province of the somatic nervous system, most of whose function is targeted at managing voluntary muscle action and responding to external sensory stimuli like touch, smell and sight.
The autonomic (also known as the visceral or automatic) nervous system, on the other hand, responds at the level of many organs and sensors without conscious control. This takes place in the glands, the gastrointestinal tract and other sites. The autonomic nervous system is divided into different component parts: the sympathetic and the parasympathetic nervous system (some people also include the enteric nervous system in this description).
Fight or Flight Versus Rest and Digest
The physiological stress response is an ancient, evolutionarily conserved function that is most interested in one thing – keeping the organism alive. When faced with a perceived life threatening situation, there is little to be gained by having conscious control of how best to prepare the body to either flee to safety or prepare to fight. This is commonly referred to as the “fight or flight” response. The sympathetic division of the autonomic nervous system plays a major role in this response.
Stimulation of the sympathetic nervous system does many things including increasing heart rate and the force of contraction of the heart muscle, shunting blood away from the organs of the gut, and increasing the respiratory rate. In large part this is done by flooding the circulation with adrenaline (also known as epinephrine) produced by the adrenal glands. When sympathetic activity is increased, the body is ready to either face the threat or leave it in the dust.
When things are calm and peaceful a different part of the autonomic nervous system exerts its influence on the body. The parasympathetic nervous system is most involved in what is known as the “rest and digest” response. Heart rate slows, digestive secretions and activity increases, and the body enters a more subdued state. This lowers the levels of stress hormones in the circulation and decreases the energy and other types of demands on the body in general. This is great when on a picnic, but not so good if a bear happens to stop by for a visit.
Too Much Stress is Bad
It does not take a tremendous amount of insight to realize that high levels of sympathetic nervous system activity can exact a toll on the body. In controlled amounts, elevated sympathetic activity is absolutely necessary to successful living. But in excessive amounts, the stress response can begin to cause problems on many fronts.
Living in a constant state of “fight or flight” exposes the body to consistently elevated levels of adrenaline and cortisol, amongst several other very important physiological modulators. Over time this is counterproductive to the concept of optimal function. Yet this is what individuals with several disorders sometimes face. In many instances, maintaining balance is very important. When it comes to the autonomic nervous system, the body functions best when it is in balance.
I can tell you for a fact when I’m stressed out that my pain from my fibromyalgia and arthritis will increase and it takes longer for the pain to go away. Does stress affect your pain?