Sympathetic system has a broader distribution, innervating effectors throughout the body
Sympathetic fibers show greater ramification.
Sympathetic preganglionic fibers may traverse through many ganglia before terminiating at its post-ganglionic cell.
Synaptic terminal arborization results in a single preganglionic fiber terminating on many post-ganglionic cells.
This anatomical characteristic is the basis for the diffuse nature of sympathic response in the human and other species.
Parasympathetic system is relatively limited
The parasympathetic system has its terminal ganglia near the end-organ.
Sometimes there is but a one-to-one ratio relationship between pre-and post-ganglionic fibers. The ratio between preganglionic vagal fibers and ganglion cells may be much higher, e.g. 1:8000 for Auerbach's plexus.
Lefkowitz, R.J, Hoffman, B.B and Taylor, P. Neurotrasmission: The Autonomic and Somatic Motor Nervous Systems, In, Goodman and Gillman's The Pharmacologial Basis of Therapeutics,(Hardman, J.G, Limbird, L.E, Molinoff, P.B., Ruddon, R.W, and Gilman, A.G.,eds) TheMcGraw-Hill Companies, Inc.,1996, pp.107
Cell bodies of preganglionic fibers: found in intermediolateral columns of the spinal cord (first thoracic to second or third lumbar segments
Preganglionic fiber axons synapse with sympathetic ganglionic neurons which lie outside the cerebrospinal axis.
Sympathetic ganglia are found at three sites:
Paraverebral ganglia: 22 interconnected pairs on either sides of the vertebral column. (para: Gr: at the side of along side)
Myelinated preganglionic fibers (white rami: thoracolumbar outflow only) leave through the anterior spinal roots.
Postganglionic fibers (gray rami) runs back to spinal nerves for distribution to:
Blood vessesls of the skin
Blood vessels of skeletal muscle
Prevertebral Ganglia: abdominal and pelvic location, comprised of:
Superior mesenteric ganglia
Aorticorenal and inferior mesenteric ganglia
Terminal Ganglia: few, residing near the innervated organ, including
Ganglia associated with the urinary bladder and rectum
Cervical ganglia (neck): three ganglia (chain) mediating vasomotor, secretory, pupillodilatory and pilomotor responses of the head and neck)
All postganglionic fibers arise from cell bodies located within these ganglia; the preganglionic fibers come from upper thoracic segments: No sympathetic preganglionic fibers come from above the first thoracic level
Adrenal medulla is similar to sympathetic ganglia.
Epinephrine is released (post-ganglionic sympathetic fibers release norepinephrine)
Chromaffin cells are innerved by preganglionic fibers that release acetylcholine.
Lefkowitz, R.J, Hoffman, B.B and Taylor, P. Neurotrasmission: The Autonomic and Somatic Motor Nervous Systems, In, Goodman and Gillman's The Pharmacologial Basis of Therapeutics, (Hardman, J.G, Limbird, L.E, Molinoff, P.B., Ruddon, R.W, and Gilman, A.G.,eds) TheMcGraw-Hill Companies, Inc.,1996, pp.105-107.