Hank takes you on a tour of your two-part autonomic nervous system. This episode explains how your sympathetic nervous system and parasympathetic nervous system work together as foils, balancing each other out. Their key anatomical differences - where nerve fibers originate and where their ganglia are located - drive their distinct anatomical functions, making your sympathetic nervous system the "fight or flight" while your parasympathetic nervous system is for "resting and digesting." Pssst... we made flashcards to help you review the content in this episode! Find them on the free Crash Course App! Download it here for Apple Devices: https://apple.co/3d4eyZo Download it here for Android Devices: https://bit.ly/2SrDulJ Chapters: Introduction: Autonomic Nervous System 00:00 Sympathetic & Parasympathetic Nervous Systems 1:35 Origins - Comparing the Sympathetic & Parasympathetic Nervous Systems 3:23 Ganglia - Comparing the Sympathetic & Parasympathetic Nervous Systems 4:11 Axon Lengths - Comparing the Sympathetic & Parasympathetic Nervous Systems 5:30 Review 7:35 Credits 8:28 *** Thanks to the following Patrons for their generous monthly contributions that help keep Crash Course free for everyone forever: Mark Brouwer, Simun Niclasen, Brad Wardell, Roger C. Rocha, Jan Schmid, Elliot Beter, Nevin Spoljaric, Sandra Aft, SR Foxley, Jessica Simmons, Stefan R. Finnerup, Jason A Saslow, Robert Kunz, Jessica Wode, Mike Drew, Steve Marshall, Anna-Ester Volozh, Christian Ludvigsen, Jeffrey Thompson, James Craver, Caitlin Steinert, BryanGriffith.com, Maia McGuire, That one guy from Midland who teaches science at highschool, Michael Longwell, Justice H, Martha (splicegrrl), Casey Rule, Manuel Kovats, and @simplscientist -- Crash Course is on Patreon! You can support us directly by signing up at http://www.patreon.com/crashcourse Want to find Crash Course elsewhere on the internet? Facebook - http://www.facebook.com/YouTubeCrashCourse Twitter - http://www.twitter.com/TheCrashCourse Instagram - https://www.instagram.com/thecrashcourse/ CC Kids: null