Show The sympathetic nervous system (SNS) is a network of nerve cells running from the brain stem down the spinal cord and out into the body to contact a wide variety of organs, including the eyes, heart, lungs, stomach and intestines, joints, and skin. From: Encyclopedia of Stress (Second Edition), 2007
The sympathetic nervous system (SNS) is one of the two divisions of the autonomic nervous system (ANS), along with the parasympathetic nervous system (PNS), These systems primarily work unconsciously in opposite ways to regulate many functions and parts of the body.
Actions[edit | edit source]The actions of the sympathetic nervous system occur in concert with other neural or hormonal responses to stress eg increases in corticotropin and cortisol secretion. Messages travel through the SNS in a bidirectional flow. Efferent messages can trigger changes in different parts of the body simultaneously. eg, the sympathetic nervous system can accelerate heart rate, widen bronchial passages, decrease motility (movement) of the large intestine, constrict blood vessels, cause pupil dilation, activate goose bumps, start sweating and raise blood pressure. The effects in which SNS acts in direct contrast to the PNS function include the following:
In humans, chronic stress results in long-term stimulation of the fight-or-flight response, which leads to constant production and secretion of catecholamines (e.g., epinephrine) and hormones such as cortisol. Long-term stress-induced secretion of these substances is associated with a variety of physiological consequences eg hyperglycemia (high blood glucose levels), which can lead to type 2 diabetes mellitus, and hypertension (high blood pressure), which can lead to cardiovascular disease[2]. Structure[edit | edit source]The sympathetic nerves run parallel to the spinal cord on both sides of the vertebral column as described below:
Overactive Sympathetic Nervous System[edit | edit source]Central sympathetic overactivity has been identified in a plethora of clinical conditions. Aside from a role in the development of hypertension, sympathetic overactivity has been implicated in the initiation and progression of numerous pathophysiological processes independent of increases in BP (e.g. vascular hypertrophy, atherosclerosis, glomerulosclerosis, and insulin resistance)[5]. In this condition, the actions of the stress hormones (eg cortisol, epinephrine and norepinephrine) are overly exerted on various organs. Long-term stress-induced secretion of these substances is associated with a variety of physiological consequences eg It affects both physical and mental health and can trigger somatic symptoms like heart palpitations, diarrhea, sweating and insomnia as well as panic attacks and chronic stress. Some of the most common causes of this condition include:
Physiotherapy Implications[edit | edit source]Many people have an overactive sympathetic nervous system[7]. Assess your clients lifestyles and be aware of the health implications. Educate them when and if appropriate. Techniques to stimulate the reduce sympathetic nervous system activity and increase vagal tone include:
References[edit | edit source]
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