Question

6. What are the two parts of the ANS? Where are their respective preganglionic neurons located? What cells give rise embryologically to their postganglionic neurons?

Answer 1

The Autonomic nervous system is divided to sympathetic and parasympathetic systems.Sympathetic nervous system connects the organs of the body to the brain through spinal nerves and is responsible for the fight or flight response. The parasympathetic system is responsible for the rest and digestive response.The preganglionic neurons of the sympathetic system are located in the lateral horn of the spinal cord from T1 to L2.   These neurons release acetylcholine that can activate nicotinic acetylcholine receptors on postgangliotic neurons. The preganglionic neurons of the parasympathetic system are located in the homologous motor nuclei of cranial nerves in brainstem or in the lateral horns of spinal cord at sacral levels. The sympathetic system and parasympathetic system is originated from basal plate of the neural tubes and neural crest cells. The preganglionic neurons arise from the base plate of the neural tube and the neural crest embryonic cells give rise to post ganglionic neurons of sympathetic nervous system. The neural crest cells also forms the post ganglionic neurons of parasympathetic within the Cranial nerve III, CN VII, CN IX, CN X and pelvic postganglion.