Sympathetic Nervous System

The sympathetic nervous system (SNS) is part of the autonomic nervous system, together with the parasympathetic and the enteric nervous systems. The SNS controls the activity of cardiac cells, smooth muscle cells, and gland cells; exerts distinct metabolic effects; and affects immune function. This entry summarizes the anatomy and physiology of the SNS, with a focus on neural circuits, effector organs, and regulatory functions.

Structural Bases of SNS Physiology

The SNS consists of preganglionic (S1N) and postganglionic (S2N) neurons. The S1N bodies are in the intermediate zone of the thoracic and lumbar segments of the spinal cord. The S2N bodies lie in interconnected ganglia either lateral or anterior to the vertebral column.

The S1N receive direct synaptic input from the presympathetic neurons (S0N), which are located in the ...

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