Sympathetic division

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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