Lymphatic System: Crash Course Anatomy & Physiology #44

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!

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

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[crashcourse]

Pssst... we made flashcards to help you review the content in this episode! Find them on the free Crash Course App!

[gldsundrp]

When I’m rich Imma start donating. We need to protect Crash course at all cost lol

[amandaputman]

Notes from the video in case anyone wants them


Lymphatic system
Quitely plays a vital supporting role to both your cardiovascular and immune systems
Maintains homeostasis by eventually returning most of the fluid that has been diverted back into your blood
Three main parts
Lymph- watery solution does not contain red blood cells, which remain in the closed circulatory loop because they are too large to pass through the capillary membrane
Lymphatic vessels help to reabsorb fluid
Lymph nodes- monitor and clean lymph as it filters through
Tonsils, adenoids, thymus, spleen
Lymphatic capillaries
Lymphatic capillaries are all over the body except for bones, bone marrow, teeth, and CNS
Lymphatic capillaries made of loosely overlapping endothelial cells that look like roofing shingles- forming flap-like valves that only open in one direction
When the pressure in the interstitial space becomes greater than the pressure inside the
Lymphatic capillary the flaps push and open and take fluid in to relive the pressure
Once the fluid inside a lymphatic capillary it is now lymph
Ducts
The right lymphatic duct drains all the lymph collected from the upper right area of the torso as well as the right arm and the right sides of the head and thorax and feeds them all into the internal jugular vein
Thoracic duct takes lymph from the rest of the body and dumps it into the subclavian vein
They operate under very low pressure
Have a series of valves that prevent backflow and are helped along by smooth muscles
Edema or swelling that can constrain blood flow
Lymph nodes
Lymph nodes house T cells that directly attack invaders and manage the immune system, b cells that secrete antibodies into the blood, macrophages that eat up foreign substances, and reticular cells that make up the stroma scaffolding network that supports all other cells in lymphoid tissues
Internally each lymph node is divided into distinct cortex and medulla regions: the outer cortex houses dividing B cells, while its deeper areas contain mostly T cells.
Lymphocytes
Lymphocytes are found in and mature in the loose reticular connective tissue that makes up a large part of the nodes and most your other lymphoid organs
The medulla contains both types of lymphocytes
Release macrophages and activate the general immune system
MALTS
Mucosa Associated Lymphoid Tissues (MALTS)- found in mucous membranes around the body, outside the lymphatic vessels
Tonsils some of the largest collections of these tissues which together form a ring around the entrance of the pharynx. Where they can inspect everything you eat and breathe
They Try to remove any pathogens before they enter the GI tract or lungs
Peyer’s Patches- in the distal portion of the small intestine
Appendix - contains a bunch of lymphoid tissue to destroy any bacteria before it can breach the intestinal wall during absorption

[gracebiggers]

Just wanted to say, I find these Crash Course videos incredibly helpful for learning about the immune system. You guys are just so good at really explaining things well and are better at helping me to visualize these concepts than a textbook is. Keep up the good work!

[angeline_]

You will be my saviour during my time in nursing school! I just need to get used to watching these more often (I only come here when I have exams coming up lol)

[augustinusskovgaardchriste]

Hank Green is a national treasure. Beat that cancer, buddy.

[arundhatisubhedar]

Could we have a Crash Course series on various diseases that affect the human body?

[Windkisssed]

That was a fantastic presentation. I have been in medicine the majority of my life and that tops any lesson I've ever had! Both informative and as always, fun to watch. Thanks for sharing with the world!
Lauri

[Chris_winthers]

It's good to know that both me and hank were here because we didn't know what the lymphatic system did

[laurenpoole]

Love the comparison of the lymphatic system to security! It's funny how a simple analogy can make information that seems overwhelming more relatable and less daunting. Thank you! :-)

[adventuresinfreezedrying]

As someone who has had Primary Lymphedema for the last 30 years, there is more information in this video on Lymphatics than what most doctors know and understand about the Lymphatic system...Thanks for helpting to educate people on their Lymphatics and why they are so important!

[Talifax]

Heard the news and had to check up here to remember what was going on! Stay well, Hank!

[jonathaneleven]

Crash Course, I just want to say to keep the good work! It helps me a lot (especially chemistry), and it'll be a shame if it stops, I appreciate the content you make.

[ajones]

Just want to express how much I appreciate these videos. Shoutout to Hank for always keeping it interesting and comical

[gorgeous]

Many *commenters say Hank speaks too fast.* That makes it a "Crash Course" & is perfect for review, but if you wanna *_slow it down to soak up info_* that's complex or new to you, *_click the gear in bottom right corner, click speed, click 0.75._* Many know this, but some don't. Hope I helped someone out! Can I get a thumbs up?

[VinOnline]

Here from Hank's latest video where he watched this to learn from himself!

[Noo]

The host is awesome and the animation makes the course that much more easy to understand as well as keeps your mind from wandering elsewhere.

[NovasYouTubeName]

We use your videos for homeschool all the time and they are fantastic! I learn along side my 3 kids! Will donate this month! Thank you!!

[Esb]

real g!!! Im in tears after this whole week studying for my intro bio class. This is the last video I'm watching for my test tomorrow, and it's really helped me! thank you so

[shonna]

For someone who found out there Lymphatic system was the reason they have been debilitating sick I appreciate these videos more than anyone will ever know. It took 2 years of neck pain, multiple diagnoses and sick with every thing you could get the whole time. PEOPLE NEED TO REALIZE!!!