The autonomic nervous system comprises two antagonistic sets of nerves, the sympathetic and parasympathetic nervous systems. The sympathetic ...autonomicnervoussystemSections&MediaArticleIntroduction&QuickFactsFastFacts2-MinSummaryMediaVideosImagesAdditionalInfoMoreArticlesOnThisTopicContributorsArticleHistoryHomeHealth&MedicineAnatomy&PhysiologyautonomicnervoussystemPrintCiteverifiedCiteWhileeveryefforthasbeenmadetofollowcitationstylerules,theremaybesomediscrepancies.Pleaserefertotheappropriatestylemanualorothersourcesifyouhaveanyquestions.SelectCitationStyleMLAAPAChicagoManualofStyleCopyCitationShareShareSharetosocialmediaFacebookTwitterURLhttps://www.britannica.com/science/autonomic-nervous-systemMoreGiveFeedbackExternalWebsitesFeedbackCorrections?Updates?Omissions?Letusknowifyouhavesuggestionstoimprovethisarticle(requireslogin).FeedbackTypeSelectatype(Required)FactualCorrectionSpelling/GrammarCorrectionLinkCorrectionAdditionalInformationOtherYourFeedbackSubmitFeedbackThankyouforyourfeedbackOureditorswillreviewwhatyou’vesubmittedanddeterminewhethertorevisethearticle.JoinBritannica'sPublishingPartnerProgramandourcommunityofexpertstogainaglobalaudienceforyourwork!ExternalWebsitesMSDmanuals-ConsumerVersion-OverviewoftheAutonomicNervousSystemByTheEditorsofEncyclopaediaBritannicaViewEditHistoryFastFacts2-MinSummaryautonomicnervoussystemSeeallmediaKeyPeople:WalterRudolfHess...(Showmore)RelatedTopics:SympatheticnervoussystemDigestivenerveplexusParasympatheticnervoussystemEntericnervoussystemVasomotorsystem...(Showmore)FullArticleautonomicnervoussystem,invertebrates,thepartofthenervoussystemthatcontrolsandregulatestheinternalorganswithoutanyconsciousrecognitionoreffortbytheorganism.Theautonomicnervoussystemcomprisestwoantagonisticsetsofnerves,thesympatheticandparasympatheticnervoussystems.Thesympatheticnervoussystemconnectstheinternalorganstothebrainbyspinalnerves.Whenstimulated,thesenervespreparetheorganismforstressbyincreasingtheheartrate,increasingbloodflowtothemuscle