Hank describes the structure and function of your lymphatic system and how it supports your cardiovascular and immune systems. He'll explain how your lymphatic system collects, filters, and returns interstitial fluid back into your bloodstream, and how your lymph nodes and lymph organs activate your immune system to fight off infections. 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: Airport Security 00:00 The Lymphatic System Structure 2:09 Origins of the Lymphatic System: Capillary Beds 3:12 Lymphatic Vessels 3:47 What Does the Lymphatic System Do? 5:05 Lymph Nodes 6:04 Mucosa-Associated Lymphoid Tissues (MALTs) 6:59 Review 8:04 *** Crash Course is on Patreon! You can support us directly by signing up at http://www.patreon.com/crashcourse Thanks to the following Patrons for their generous monthly contributions that help keep Crash Course free for everyone forever: Mark, Eric Kitchen, Jessica Wode, Jeffrey Thompson, Steve Marshall, Moritz Schmidt, Robert Kunz, Tim Curwick, Jason A Saslow, SR Foxley, Elliot Beter, Jacob Ash, Christian, Jan Schmid, Jirat, Christy Huddleston, Daniel Baulig, Chris Peters, Anna-Ester Volozh, Ian Dundore, Caleb Weeks -- Want to find Crash Course elsewhere on the internet? Facebook - http://www.facebook.com/YouTubeCrashCourse Twitter - http://www.twitter.com/TheCrashCourse Tumblr - http://thecrashcourse.tumblr.com Support Crash Course on Patreon: http://patreon.com/crashcourse CC Kids: http://www.youtube.com/crashcoursekids