RT Book, Section
A1 Nestler, Eric J.
A1 Hyman, Steven E.
A1 Holtzman, David M.
A1 Malenka, Robert C.
SR Print(0)
ID 1105915986
T1 Autonomic Nervous System
T2 Molecular Neuropharmacology: A Foundation for Clinical Neuroscience, 3e
YR 2015
FD 2015
PB McGraw-Hill Education
PP New York, NY
SN 9780071827690
LK neurology.mhmedical.com/content.aspx?aid=1105915986
RD 2024/04/25
AB The  autonomic  nervous  system  plays  a  central  role  in  maintaining  homeostasis  and  regulates  almost  every  organ  system  in  the  body.The  major  functional  divisions  are  the  sympathetic  and  parasympathetic  nervous  systems.  A  third  division,  the  enteric  nervous  system,  is  an  intrinsic  neural  network  that  regulates  gastrointestinal  function.In  most  organs,  the  sympathetic  and  parasympathetic  nervous  systems  produce  functionally  opposite  effects  and  can  be  viewed  in  simple  terms  as  physiologic  antagonists.The  sympathetic  nervous  system  is  activated  in  response  to  changes  in  the  environment  and  produces  a  coordinated  “fight-or-flight”  response  to  a  threat.The  parasympathetic  nervous  system  is  continuously  active,  and  coordinates  the  function  of  multiple  organs  in  accord  with  the  physiologic  state  of  the  organism,  thereby  facilitating  such  functions  as  digestion  and  excretion.Because  of  its  importance  to  the  physiology  of  the  organism,  the  autonomic  nervous  system  is  a  target  for  many  pharmacologic  interventions  and  is  also  responsible  for  the  untoward  effects  of  many  medications  and  toxins.The  peripheral  autonomic  nervous  system  (both  sympathetic  and  parasympathetic  divisions)  consists  of  a  preganglionic  neuron  in  the  brainstem  or  spinal  cord  that  innervates  postganglionic  neurons  in  peripheral  autonomic  ganglia.  Synaptic  transmission  in  the  autonomic  ganglia  is  mediated  by  acetylcholine  interacting  with  a  nicotinic  receptor  that  is  pharmacologically  distinct  from  receptors  in  the  brain  or  at  the  neuromuscular  junction.  The  postganglionic  neurons  innervate  target  organs  throughout  the  body.Acetylcholine  is  the  main  neurotransmitter  used  by  parasympathetic  postganglionic  neurons;  its  target  receptors  are  muscarinic  acetylcholine  receptors.With  a  few  exceptions,  postganglionic  sympathetic  neurons  release  norepinephrine,  which  acts  on  α-  and  β-adrenergic  receptors  located  on  end  organs.