Sympathetic division:
• sometimes called the thoracolumbar division (arises from thoracic and lumbar regions of the spinal cord); preganglionic somas are in lateral horns of gray matter; fibre exit as spinal nerves T1 to L2 lead to sympathetic chain of paravertebral ganglia that are along each side of the vertebral column; preganglionic neurons synapse with postganglionic neurons in the paravertebral ganglia in a ratio of about 1 to 17; post ganglionic nerve fibres follow 3 routes – spinal nerve route (after exiting, they return to spinal nerve and travel to target organ; eg sweat glands, blood vessels of skeletal muscles), sympathetic nerve route (to heart, lungs, oesophagus, thoracic blood vessels), and the splanchnic nerve route (fibres that pass through paravertebral ganglia without synapsing form splanchnic nerves)
• postganglionic neurons are longer than the preganglionic neurons (opposite of parasympathetic division)
• more active in stressful situation – “flight or fight” functions; regulates the cardiovascular system (to maintain blood flow to brain; redistribute blood flow during exercise; vasodilation to compensate for blood loss; increased force of cardiac muscle contraction); body temperature (regulates blood flow to skin; sweat gland production; piloerection); dilate pupil; increased sweat production; dilates bronchial tree from relaxation of bronchial smooth muscle
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