Thursday, May 31, 2012

What is the autonomic nervous system? Summary


What is the autonomic nervous system?
Summary for http://en.wikipedia.org/wiki/Autonomic_nervous_system
  • The autonomic nervous system (ANS or visceral nervous system or involuntary nervous system) is the part of the peripheral nervous system that acts as a control system functioning largely below the level of consciousness, and controls visceral functions. [1] The ANS affects heart rate, digestion, respiratory rate, salivation, perspiration, pupillary dilation, micturition (urination), and sexual arousal. (188)
  • It is classically divided into two subsystems: the parasympathetic nervous system (PSNS) and sympathetic nervous system (SNS). neurons (because they use nitric oxide as a neurotransmitter) have been described and found to be integral in autonomic function, particularly in the gut and the lungs. (146)
  • The following table reviews the actions of these neurotransmitters as a function of their receptors. α1: stimulates potassium secretions M3: stimulates watery secretions lacrimal glands (tears) β: stimulates protein secretion [12] --- juxtaglomerular apparatus of kidney β1:[5] renin secretion --- parietal cells --- M1: Gastric acid secretion liver α1, β2: glycogenolysis, gluconeogenesis --- adipose cells β1,[5] β3: stimulates lipolysis --- GI tract (smooth muscle) motility α1, α2,[13] β2: decreases M3, (M1) [4]: increases sphincters of GI tract α1,[5] α2,[4] β2: contracts M3:[5] relaxes glands of GI tract no effect [4] M3: secretes [edit] Endocrine system Target Sympathetic (adrenergic) Parasympathetic (muscarinic) pancreas (islets) α2: decreases insulin secretion from beta cells, increases glucagon secretion from alpha cells M3[14][15]: increases secretion of both insulin and glucagon. eMedicine/Stedman Medical Dictionary Lookup!". . Retrieved 2008-11-30. (202)
Best words:
  1. neurons (20)
  2. parasympathetic (16)
  3. system (16)
  4. nervous (16)
  5. sympathetic (16)
  6. visceral (10)
  7. sensory (9)
  8. ganglia (8)
  9. spinal (8)
  10. division (8)
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  4. The autonomic nervous system (ANS or visceral nervous system or involuntary nervous system) is the part of the peripheral nervous system that acts as a control system functioning largely below the level of consciousness, and controls visceral functions. [1] The ANS affects heart rate, digestion, respiratory rate, salivation, perspiration, pupillary dilation, micturition (urination), and sexual arousal.
  5. Whereas most of its actions are involuntary, some, such as breathing, work in tandem with the conscious mind.
  6. The ANS is located in the medulla oblongata which is then divided into the rcc(respiratory control centre) the ccc(cardiac control centre) and the vmc(vasomotor centre).
  7. These then subdivide into other areas.
  8. The ccc to parasympathetic and sympathetic, the rcc to inspiratory control centre and expiratory control centre.
  9. It is classically divided into two subsystems: the parasympathetic nervous system (PSNS) and sympathetic nervous system (SNS). neurons (because they use nitric oxide as a neurotransmitter) have been described and found to be integral in autonomic function, particularly in the gut and the lungs.
  10. With regard to function, the ANS is usually divided into sensory (afferent) and motor (efferent) subsystems.
  11. Within these systems, however, there are inhibitory and excitatory synapses between neurons.
  12. The enteric nervous system is sometimes considered part of the autonomic nervous system, and sometimes considered an independent system.
  13. ANS innervation is divided into sympathetic nervous system and parasympathetic nervous system divisions.
  14. The sympathetic division has thoracolumbar “outflow”, meaning that the neurons begin at the thoracic and lumbar (T1-L2) portions of the spinal cord.
  15. The parasympathetic division has craniosacral “outflow”, meaning that the neurons begin at the cranial nerves (CN 3, CN7, CN 9, CN10) and sacral (S2-S4) spinal cord.
  16. The ANS is unique in that it requires a sequential two-neuron efferent pathway; the preganglionic neuron must first synapse onto a postganglionic neuron before innervating the target organ.
  17. The preganglionic, or first, neuron will begin at the “outflow” and will synapse at the postganglionic, or second, neuron’s cell body.
  18. The post ganglionic neuron will then synapse at the target organ.
  19. The sympathetic division (thoracolumbar outflow) consists of cell bodies in the lateral horn of spinal cord (intermediolateral cell columns) from T1 to L2.
  20. These cell bodies are GVE (general visceral efferent) neurons and are the preganglionic neurons.
  21. These ganglia provide the postganglionic neurons from which innervation of target organs follows.
  22. These all contain afferent (sensory) nerves as well, known as GVA (general visceral afferent) neurons.
  23. The parasympathetic division (craniosacral outflow) consists of cell bodies from one of two locations: brainstem (Cranial Nerves III, VII, IX, X) or sacral spinal cord (S2, S3, S4).
  24. These ganglia provide the postganglionic neurons from which innervations of target organs follows.
  25. The sensory arm is made of “primary visceral sensory neurons” found in the peripheral nervous system (PNS), in “cranial sensory ganglia”: the geniculate, petrosal and nodose ganglia, appended respectively to cranial nerves VII, IX and X.
  26. These sensory neurons monitor the levels of carbon dioxide, oxygen and sugar in the blood, arterial pressure and the chemical composition of the stomach and gut content. (They also convey the sense of taste, a conscious perception).
  27. Blood oxygen and carbon dioxide are in fact directly sensed by the carotid body, a small collection of chemosensors at the bifurcation of the carotid artery, innervated by the petrosal (IXth) ganglion.
  28. Primary sensory neurons project (synapse) onto “second order” or relay visceral sensory neurons located in the medulla oblongata, forming the nucleus of the solitary tract (nTS), that integrates all visceral information.
  29. The nTS also receives input from a nearby chemosensory center, the area postrema, that detects toxins in the blood and the cerebrospinal fluid and is essential for chemically induced vomiting or conditional taste aversion (the memory that ensures that an animal which has been poisoned by a food never touches it again).
  30. Motor neurons of the ANS are also located in ganglia of the PNS, called “autonomic ganglia”.
  31. They belong to three categories with different effects on their target organs (see below “Function”): sympathetic, parasympathetic and enteric.
  32. Sympathetic ganglia are located in two sympathetic chains close to the spinal cord: the prevertebral and pre-aortic chains.
  33. Parasympathetic ganglia, in contrast, are located in close proximity to the target organ: the submandibular ganglion close to salivary glands, paracardiac ganglia close to the heart etc...
  34. Enteric ganglia, which as their name implies innervate the digestive tube, are located inside its walls and collectively contain as many neurons as the entire spinal cord, including local sensory neurons, motor neurons and interneurons.
  35. It is the only truly autonomous part of the ANS and the digestive tube can function surprisingly well even in isolation.
  36. For that reason the enteric nervous system has been called “the second brain”. ) located in the central nervous system.
  37. Preganglionic sympathetic neurons are in the spinal cord, at thoraco-lumbar levels.
  38. Preganglionic parasympathetic neurons are in the medulla oblongata (forming visceral motor nuclei: the dorsal motor nucleus of the vagus nerve (dmnX), the nucleus ambiguus, and salivatory nuclei) and in the sacral spinal cord.
  39. Enteric neurons are also modulated by input from the CNS, from preganglionic neurons located, like parasympathetic ones, in the medulla oblongata (in the dmnX).
  40. The feedback from the sensory to the motor arm of visceral reflex pathways is provided by direct or indirect connections between the nucleus of the solitary tract and visceral motoneurons.
  41. Sympathetic and parasympathetic divisions typically function in opposition to each other.
  42. But this opposition is better termed complementary in nature rather than antagonistic.
  43. For an analogy, one may think of the sympathetic division as the accelerator and the parasympathetic division as the brake.
  44. The sympathetic division typically functions in actions requiring quick responses.
  45. The parasympathetic division functions with actions that do not require immediate reaction. feed and breed". situations.
  46. For example, standing up from a reclining or sitting position would entail an unsustainable drop in blood pressure if not for a compensatory increase in the arterial sympathetic tonus.
  47. Another example is the constant, second to second modulation of heart rate by sympathetic and parasympathetic influences, as a function of the respiratory cycles.
  48. More generally, these two systems should be seen as permanently modulating vital functions, in usually antagonistic fashion, to achieve homeostasis.
  49. Some typical actions of the sympathetic and parasympathetic systems are listed below. response, corresponds with arousal and energy generation, and inhibits digestion. response, promotes calming of the nerves return to regular function, and enhances digestion.
  50. The following table reviews the actions of these neurotransmitters as a function of their receptors. α1: stimulates potassium secretions M3: stimulates watery secretions lacrimal glands (tears) β: stimulates protein secretion [12] --- juxtaglomerular apparatus of kidney β1:[5] renin secretion --- parietal cells --- M1: Gastric acid secretion liver α1, β2: glycogenolysis, gluconeogenesis --- adipose cells β1,[5] β3: stimulates lipolysis --- GI tract (smooth muscle) motility α1, α2,[13] β2: decreases M3, (M1) [4]: increases sphincters of GI tract α1,[5] α2,[4] β2: contracts M3:[5] relaxes glands of GI tract no effect [4] M3: secretes [edit] Endocrine system Target Sympathetic (adrenergic) Parasympathetic (muscarinic) pancreas (islets) α2: decreases insulin secretion from beta cells, increases glucagon secretion from alpha cells M3[14][15]: increases secretion of both insulin and glucagon. eMedicine/Stedman Medical Dictionary Lookup!". . Retrieved 2008-11-30.
  51. Nitric oxide is the endogenous neurotransmitter of bronchodilator nerves in humans Maria G. Belvisi, C.
  52. David Stretton, Magdi Yacouba, Peter J. Barnes". . a b c d e f g h i j k l m n Rang, Dale, Ritter & Moore (2003). Pharmacology 5th ed.. Churchill Livingstone. p.  127. ISBN 0-443-07145-4. a b c d e f g h i j k l m Page 37 in: Costanzo, Linda S. (2007). Physiology.
  53. Hagerstwon, MD: Lippincott Williams & Wilkins. ISBN 0-7817-7311-3.
  54. Coronary vasoconstriction mediated by alpha 1- and alpha 2-adrenoceptors in conscious dogs O. L. Woodman and S. F. Rang, H. P. (2003). Pharmacology.
  55. Edinburgh: Churchill Livingstone. ISBN 0-443-07145-4.
  56. Circulation & Lung Physiology I M. A. S. T. E. R. Elliott, J (1997).
  57. Alpha-adrenoceptors in equine digital veins: Evidence for the presence of both alpha1 and alpha2-receptors mediating vasoconstriction".
  58. Journal of Veterinary Pharmacology & Therapeutics (Blackwell Publishings) 20 (4): 308–317. DOI:10. 1046/j. 1365-2885. 1997. 00078. x. PMID 9280371. ;jsessionid=8lm5thggpj1x. alice? format=print.
  59. Protein secretion induced by isoproterenol or pentoxifylline in lacrimal gland P. Mauduit, G. Herman and B.
  60. Sagrada, A; Fargeas, MJ; Bueno, L. , A; Fargeas, MJ; Bueno, L (1987).
  61. Involvement of alpha-1 and alpha-2 adrenoceptors in the postlaparotomy intestinal motor disturbances in the rat". Gut 28 (8): 955–959. DOI:10. 1136/gut. 28. 8. 955. PMC 1433140. PMID 2889649. // ;artid=1433140. a b Page 47 in: Poretsky, Leonid (2010).
  62. Principles of diabetes mellitu. New York: Springer.
  63. ISBN 978-0-387-09840-1. a b Duttaroy, A. ; Zimliki, C. L. ; Gautam, D. ; Cui, Y. ; Mears, D. ; Wess, J. (2004).
  64. Muscarinic Stimulation of Pancreatic Insulin and Glucagon Release is Abolished in M3 Muscarinic Acetylcholine Receptor-Deficient Mice".
  65. Diabetes 53 (7): 1714–1720. DOI:10. 2337/diabetes. 53. 7. 1714. PMID 15220195.
  66. Nerves – autonomic nervous system (sympathetic nervous system/ganglion/trunks and parasympathetic nervous system/ganglion) (TA A14. 3, GA 9.
What is the autonomic nervous system?

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