Sympathetic nervous system

The Sympathetic nervous system (SNS) is one of the two main divisions of the autonomic nervous system (ANS), the other being the parasympathetic nervous system (PNS). The autonomic nervous system functions to regulate the body's unconscious actions. The sympathetic nervous system's primary process is to stimulate the body's fight-or-flight response. It is, however, constantly active at a basic level to maintain homeostasis.

Structure

The sympathetic nervous system is part of the autonomic nervous system, which also includes the parasympathetic nervous system and the enteric nervous system. The sympathetic nervous system is responsible for up- and down-regulating many homeostatic mechanisms in living organisms.

Function

The sympathetic nervous system is responsible for the body's response to stress or danger. It increases heart rate, blood pressure, and blood glucose levels; dilates the pupils; and slows digestion. It also has important roles in the control of most of the body's internal organs.

Clinical significance

Dysfunction of the sympathetic nervous system can lead to a variety of clinical conditions, such as hypertension, heart failure, and anxiety disorders.

See also

• Autonomic nervous system
• Parasympathetic nervous system
• Enteric nervous system

External links

• Sympathetic Nervous System at Britannica

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  Sympathetic innervation diagram
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  Diagram of the sympathetic nervous system
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  Sympathetic nervous system pathways
• Sympathetic nervous system
  Sympathetic nervous system