Why Do Our Bones Make Our Blood?

3 839 Shikime 387 mijë

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Our bones are multi-functional body builders, but perhaps their most mysterious function is the production of blood. Scientists now think they have a pretty good idea why this is where our blood gets made.

Hosted by: Hank Green

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Sources:doi.org/10.1038/s41586-018-0213-0 pubmed.ncbi.nlm.nih.gov/21566758/pubmed.ncbi.nlm.nih.gov/29907823/www.ncbi.nlm.nih.gov/pmc/articles/PMC1555080/stemcells.nih.gov/info/2001report/chapter5.htm Image Sources:www.storyblocks.com/video/stock/dancing-skeleton--animation-green-background-loop-h_n-gx1cwkjgtc7lgwww.istockphoto.com/photo/northern-cardinal-gm172262353-3715783www.istockphoto.com/photo/topical-saltwater-clownfish-gm108270220-9016363www.istockphoto.com/photo/red-eyed-tree-frog-smile-gm1049028724-280573845www.istockphoto.com/vector/dog-bone-gm481971399-22818540www.istockphoto.com/photo/blood-cells-gm1257429592-368507071www.istockphoto.com/vector/vector-background-gm1167677658-322110997www.istockphoto.com/vector/hematopoietic-stem-cell-gm499405345-42410804www.istockphoto.com/vector/vector-set-of-sun-icons-gm1163216334-319333753www.istockphoto.com/vector/human-bone-anatomy-gm1218464203-356050584www.istockphoto.com/vector/blackboard-chalkboard-green-empty-gm481131675-36861090www.storyblocks.com/video/stock/underwater-ocean-waves-ripple-and-flow-with-light-rays-loop-sfjmg3-hxix9gmruuwww.istockphoto.com/vector/people-have-heatstroke-concept-illustration-gm858472098-141632245www.nature.com/articles/s41586-018-0213-0#citeaswww.istockphoto.com/vector/vector-illustration-of-blue-umbrella-vector-set-on-white-background-gm1131169719-299428618www.istockphoto.com/vector/bright-rays-background-gm1157721782-315979058www.istockphoto.com/vector/skelettben-gm1062656882-284101041www.storyblocks.com/video/stock/inspection-of-blood-in-the-blood-vessels-of-the-circulatory-system-soy0swk5ika4wmtyiwww.istockphoto.com/vector/conveyor-belt-with-cardboard-boxes-at-factory-gm1275766018-375786051www.istockphoto.com/vector/drop-gm1081786788-290097354www.istockphoto.com/vector/safety-goggles-isolated-on-blue-background-with-a-shadow-underneath-gm833076746-135581363www.istockphoto.com/vector/creative-vector-illustration-of-factory-line-manufacturing-industrial-plant-scen-gm1136878200-302941711


  1. SciShow
    26 ditë më parë

    Go to Brilliant.org/SciShow to try their Physics of the Everyday course. Sign up now and get 20% off an annual Premium subscription.

    1. Al To
      Al To
      7 ditë më parë

      @Dan R. And similar evoluve like squids and others animals in convergent evolution, the same goal or comon point to evoluve in diferents eyes, pupils and animal acuátic and land, very strange.

    2. Joziah Remington
      Joziah Remington
      8 ditë më parë

      @Dexter Ernest Wow! Took like 15 minutes but it reallyworked!!

    3. Dexter Ernest
      Dexter Ernest
      8 ditë më parë

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    4. Sanjitha C
      Sanjitha C
      11 ditë më parë

      Say about the healthness of teeth..... What happens if our teeth became yellow 🟡...?

    5. Mavvet
      16 ditë më parë

      I heard and theory that humans became smarter by eating bone merrow

  2. The Voices Told Me To Again
    The Voices Told Me To Again
    2 ditë më parë


  3. Gufran Ahmad
    Gufran Ahmad
    3 ditë më parë

    If you dig up a grave you will find a huge pile of blood

  4. ZeroSum Game
    ZeroSum Game
    3 ditë më parë

    I'm just starting this episode, but I've Thought about this, so here goes my prediction. Bones make our blood because without blood, all other functions will cease, making blood production something that needs to be a core process. Given that bones are throughout our body, difficult to accidently have removed without losing blood-needing flesh, and extremely well armored, bones take up the role of protecting our organs and also produce a constant supply across the whole organism. I just realized that Organism probably has something in common with the word "organized," but I don't know which came first, so no conjecture on that, I just had a thought and wanted to share it, raw.

  5. B
    5 ditë më parë

    For the algorithm.

  6. A form of matter
    A form of matter
    5 ditë më parë

    I always assumed it was because all the other organs are already doing stuff & there's no reason not to make blood in bones

  7. shadowofthecandle
    6 ditë më parë

    Um Hank what the F is your shirt

  8. Alex Zetsu
    Alex Zetsu
    7 ditë më parë

    Putting blood making cells where it is dark makes sense, but I don't see why it can't take place in a liver. In primates like humans, the liver is also a dark place. Our keratinocytes and melanocytes in our skin make pretty much out entire body dark.

  9. What The Fu
    What The Fu
    7 ditë më parë

    I just love science 😍

  10. Alex Eddon
    Alex Eddon
    13 ditë më parë

    What happens to the marrow when you break your bones?

  11. Gacha Brixit Biscuits
    Gacha Brixit Biscuits
    13 ditë më parë

    Your bones are bloody~

  12. William Shakemilk
    William Shakemilk
    14 ditë më parë

    wat? they do?

  13. Moses Greer
    Moses Greer
    14 ditë më parë

    What I really love is that hank answered this exact question on tiktok... Like a month before this video came out.

  14. Nwabueze Ozuzu
    Nwabueze Ozuzu
    15 ditë më parë

    And someone will tell me there is life on other planets in our solar system. Not possible. There could be life on other solar systems, but not ours

  15. Ace Of Spades
    Ace Of Spades
    15 ditë më parë

    Why do bones make our blood? Because we need it

  16. ᛬ᚻᚫᛚᛖᚾᛞ ᛫ ᚱᛖᚪᛞᛚᚪᚾᛞ᛬
    ᛬ᚻᚫᛚᛖᚾᛞ ᛫ ᚱᛖᚪᛞᛚᚪᚾᛞ᛬
    15 ditë më parë

    because there’s space for it

  17. ivan rubio
    ivan rubio
    16 ditë më parë

    Me who thinks it's made of water we drink..

  18. Some Body
    Some Body
    16 ditë më parë

    Untill now i thought that blood was just there in our body 🤦

  19. xx10taci0nxx
    16 ditë më parë

    Wolverine has left the chat !!

  20. Brian Reeves
    Brian Reeves
    16 ditë më parë

    Pee is stored in the bones

  21. Allez Venga
    Allez Venga
    17 ditë më parë

    Thanks for your sharing

  22. Purplex_Purple 77
    Purplex_Purple 77
    17 ditë më parë

    Im goad you brought up catfish. If i was trying to prove this. Id compare a fish in a pond or shallow water to a deep depth fish.

  23. Old Fogey
    Old Fogey
    17 ditë më parë

    So if you have degenerative disc disease bad bones how does this affect blood production or does it? I didnt know humans bones made blood? As it was a topic i never pondered!

  24. Mark Dawson
    Mark Dawson
    17 ditë më parë

    Really interesting, thanks!

  25. Joseph Buckley
    Joseph Buckley
    18 ditë më parë

    But I still don’t know how the blood inside the bones gets out into the normal bloodstream since the bones seem to be sealed smooth . So how does it get out into the rest of the body???

  26. andres
    18 ditë më parë

    what I doubt about this theory is why bones like the skull, and the collarbones have red bone marrow... the skull is like 5mm thick overall, the skull's external layer is at most 2mm, and that's thick for what I've seen, the head is also one of the most exposed to sun body parts, just imagine, if a dim light like a flashlight can cross through a finger, sunlight can cross the skull, even more with bald people, I'm sure most light can, at least reach the diploe where red bone marrow is... and liver or kidneys are way more protected, also, both organs can produce blood cells at least in embryonal stages, there's no reason to switch that places if is because of sunlight. if I had to give another reason, but that's just pure speculation, it should be infections, bones almost allways get infected because of severe wounds, and if an infection reaches them is usually diseases like tuberculosis or syphilis, which are extremely invasive... kidneys can get injured by pyelonephritis and the liver by hepatitis... BTW they have strong evidence with fishes and amphibians... but is still weird in my opinion that more exposed bones are apparently more capable of preserve red bone marrow than other, better protected like the femur

  27. Juan Martin Paez
    Juan Martin Paez
    18 ditë më parë

    Hey Hank, just a friendly reminder! Humans also begin prenatal haematopoiesis in our liver, spleen and other tissues, migrating production to the bones after the marrow develops, so I guess we have more in common with frogs than meets the eye haha. It’s also worth noting that these organs maintain the ability to resume blood production extramedulllary in certain conditions like chronic inflammation or disease, even during adulthood. Great videos, keep it up!

  28. Naygoats
    18 ditë më parë

    No wonder my grandma died of blood lose when she got a hip replacement

  29. Cassian YHVH
    Cassian YHVH
    18 ditë më parë

    I get that the body doesn't want to make blood cells close to the surface of the skin but that leaves many other candidate organs other than bones to get the job of making cells. I didn't hear a convincing argument for why bones rather than spleen, liver or numerous other organs. What am I missing. I doubt there is any less UV light in bones versus those other organs.

  30. Yash Sharma
    Yash Sharma
    18 ditë më parë

    प्र: - हड्डियाँ अपने शरीर खून क्यों बनाती हैं? हड्डियाँ - ऐसे ही सेक्सी लग रहा था।

  31. Braden Ripple
    Braden Ripple
    19 ditë më parë

    Red blood cells, lasting on average 120 days, don't have their own DNA, they're grown by exocytosis of cells in the bones that get packaged with just RNA and protein. So, this make sense because the original DNA must be transcribed much more than the average cell.

  32. Tomas Larsson
    Tomas Larsson
    19 ditë më parë

    I always wondered why marrow was also the source of blood but never looked into it. Makes sense though. I like this idea and I like the evidence.

  33. IceFalken Ace
    IceFalken Ace
    19 ditë më parë

    Blood production moved to the bones because their Union offered a better deal to Body Management. It was NOT a hostile takeover like the rumors were saying.

  34. Brendan Peck
    Brendan Peck
    19 ditë më parë

    How do plants move Oxygen into their roots?

  35. Brendan Peck
    Brendan Peck
    19 ditë më parë

    Why haven't I wondered this before?

  36. fiona davis
    fiona davis
    19 ditë më parë

    How do HABs produce their actual toxins? Is it a defense mechanism or does it just happen during blooms?

  37. The Viewer
    The Viewer
    19 ditë më parë

    What happens then when u brake a bone? I feel every bone in my body after watching this, chilling

  38. Mohammed
    19 ditë më parë

    Blood migrates to bones because bones are the safest place from radiation. Humans use xray radiation because bones are the only tissue that absorbs them. Nice job, body.

  39. Mass Hysteria
    Mass Hysteria
    20 ditë më parë

    So it’s not your bones that make blood but the marrow in your bones.

  40. Diana Estabrook
    Diana Estabrook
    20 ditë më parë

    I don't know why, but for some reason I never thought frogs had bones. Like it makes perfect sense I just...

  41. Chronicom • 30 years ago
    Chronicom • 30 years ago
    20 ditë më parë

    But how tho?

  42. Harsh Parekh
    Harsh Parekh
    20 ditë më parë

    So D3 for bones requires sunlight and RBC from bones requires lack of sunlight. weird.

  43. Tray Chester
    Tray Chester
    20 ditë më parë

    why did i have to read the title of this video at 3 am?

  44. Jetoler
    20 ditë më parë

    I make my bones in my blood

  45. Alani G
    Alani G
    20 ditë më parë

    My pregnancy app says at week 30 babies stop making red blood cells in the spleen and start doing it in the bone marrow.

  46. Kc Flick
    Kc Flick
    20 ditë më parë

    I voted for this one

  47. Barbe Online
    Barbe Online
    20 ditë më parë

    The light angle is interesting. When I first heard the question my immediate thought was that the reason is because that is where there is available space. Engineers learn that hollow tubes support as well if not better than solid cylinders. And our bodies are a near masterpiece of efficient use of space. So the only question is what would evolve to reside in the bone cavities.

  48. 1992it
    20 ditë më parë

    wait a minute, are they saying our skin is transparent to UV rays? won't your skin block it?

  49. I am S.J
    I am S.J
    20 ditë më parë

    Wait, so my bones are wet?

  50. Bennidict Salvador
    Bennidict Salvador
    21 ditë më parë

    I remember seeing this topic on Hank's tiktok lol

  51. Sutav
    21 ditë më parë

    they casually ENGENEERED FISH to do whatever they want

  52. Khlotho Stonney
    Khlotho Stonney
    21 ditë më parë

    so bone broth is healthy?

    1. Eko Subandie
      Eko Subandie
      19 ditë më parë

      Bone marrow are quite nutritious probably more so than the meat themselves

  53. paringatai
    21 ditë më parë

    the definition of"expert";- So..."X' typically signifies the unknown factor....and "spurt" is what you get when you put a drip under pressure

  54. Megadextrious
    21 ditë më parë

    Now I understand why radiation causes Aplastic Anemia.. It all makes sense now. Neato, science gang!💪🏻👏🏻

  55. Manduul Bakhdal
    Manduul Bakhdal
    21 ditë më parë

    Does having healthy bones mean less likelihood of anaemia?

  56. Marcus Boyd
    Marcus Boyd
    21 ditë më parë

    i want that shirt

  57. Ally Lucy
    Ally Lucy
    21 ditë më parë

    The superficial lion generically yell because slime daily found following a psychotic dorothy. tired, aware fifth

  58. Keallei
    21 ditë më parë

    I wonder if the all white cave animals don’t have the kidney umbrellas since they live in the dark.

  59. Rathish Rana
    Rathish Rana
    22 ditë më parë

    The thumbnail is dope!

  60. Wesson Liam
    Wesson Liam
    22 ditë më parë

    To prevent us from replacing them with metal and throwing them in the bin.

  61. Rob Francis
    Rob Francis
    22 ditë më parë

    Maybe theyre sensitive to xray radiation.

  62. BR28
    22 ditë më parë

    "Because the inside of our bones... are dark", isnt.. isnt the outside of the bone dark too? Isn't everything inside my body dark? This is the light in the refrigerator all over again.

  63. Much2Troublesome
    22 ditë më parë

    Now we need a follow up video of HOW blood is made in the bones please

  64. Saumajit Chakraborty
    Saumajit Chakraborty
    22 ditë më parë

    3:07 "readies them for a bright future on land" Word play exists 😎

  65. Loveland Girl
    Loveland Girl
    22 ditë më parë

    God created it to be made in the bones.

  66. Cathedral Vallory
    Cathedral Vallory
    22 ditë më parë

    Without bones no blood

  67. TBW The Bearded Wonder
    TBW The Bearded Wonder
    22 ditë më parë

    I've been avoiding this video but it creeped into my head again today so here I am

  68. Cosmiccoffeecup
    22 ditë më parë

    I didn't know I didn't know this.

  69. Curtis Franks
    Curtis Franks
    22 ditë më parë

    Why are our bones not black? Do we just not need that extra protection?

  70. Jumping Fan
    Jumping Fan
    22 ditë më parë

    STOP TALKING ABOUT EVOLUTION. Evolution isn't science since "macro" evolution has not and cannot be observed.

    1. Jumping Fan
      Jumping Fan
      22 ditë më parë

      @jaymz1999 basically you need to be more precise with what you say.. its not honest if your being vague.. but when i said evolution i was clearly talking of the evolution mentioned in the video.. ie macro evolution. which is a species going from one species to another, as with the common picture of all animals coming back to the singular ancient ancestor. That is neither repeatable nor observable.. its in the past. And therefore also it is said to be exclusively the work of nature too.. so not even testable/measurable. All we can test is what we see. Evolution is certainly a faulty faith.

    2. Jumping Fan
      Jumping Fan
      22 ditë më parë

      @jaymz1999 evolution is defined as either macro or micro... i do agree micro evolution is those things that you said. We can breed a dog and get it to produce a certain kind of dog that we desire. But know that we cant breed dogs with certain others.. "Dogs can also be bred with a few other species to produce a "hybrid." Dog, wolves, dingoes, coyotes, and golden jackals are interfertile which means they share enough DNA and biology in common to breed and produce litters. However, other members of the genus Canis cannot breed with domestic dogs including foxes, African wild dogs, and side-striped and black-backed jackals." dogs.lovetoknow.com/dog-breeding-pregnancy/advantages-disadvantages-cross-breeding-dogs#:~:text=What%20Is%20Cross%2DBreeding%3F,dogs%20are%20all%20one%20species.

    3. jaymz1999
      22 ditë më parë

      @Jumping Fan Evolution is a well proven fact. It is observable, testable and repeatable.

    4. Jumping Fan
      Jumping Fan
      22 ditë më parë

      @jaymz1999 Macro evolution is not provable since it can't be observed. In short.. evolution is not a well proven fact.

    5. jaymz1999
      22 ditë më parë

      Evolution is a well proven fact.

  71. another mouth
    another mouth
    22 ditë më parë

    Hemapoetic cells...those cells must be very poetic

  72. The Pimp
    The Pimp
    23 ditë më parë

    Cuz they feel like it

  73. Paige Lego
    Paige Lego
    23 ditë më parë

    Why does bone have blood in it?

  74. fatehyabali
    23 ditë më parë


  75. Craig O
    Craig O
    23 ditë më parë

    Why? So your bones can heal too.

  76. Sondreara
    23 ditë më parë

    How am I supposed to pay attention when you’ve got such a rad shirt on?!

  77. DunnickFayuro
    23 ditë më parë

    A lot of blood cells are actually made in the lungs though

  78. Ben McReynolds
    Ben McReynolds
    23 ditë më parë

    Bones: "Oh so you think we're stiff & bland?" Bones: "Alright bet!"

  79. KnightOfGaea
    23 ditë më parë

    You should watch Cells At Work. It's a fun little anime that actually does a decent job describing how the cardiovascular system works.

  80. Likith Charan
    Likith Charan
    23 ditë më parë


  81. BLOOD
    23 ditë më parë

    so if a replace one of my bones with deadpool i will have the healing factor too basically.

  82. Ron Ronson
    Ron Ronson
    23 ditë më parë

    I'm confused. I was always taught that UV light doesn't penetrate much. It doesn't even penetrate windows, much less your dermis. Or so I thought. So why would being in your bones be any more protected than anywhere else below your dermis? I'm apparently misinformed on this, but hopefully someone can explain.

  83. Forrest Boone
    Forrest Boone
    23 ditë më parë

    why are humans not completely covered in hair?

  84. Nabre Labre
    Nabre Labre
    23 ditë më parë

    So thats why bone diseases are so bad

  85. Peter Olbrisch
    Peter Olbrisch
    23 ditë më parë

    Because apparently the rest of our body is unconcerned with such frivolities.... It's not my job man.

  86. Sir loin of beef
    Sir loin of beef
    23 ditë më parë

    The skeletons run the *_blood factory_*

  87. HighEndMe
    23 ditë më parë

    Just wanna say that Hank Green is a precious internet educator and deserves recognition for it. Thanks for the continuously great content!

  88. HighEndMe
    23 ditë më parë

    Pristine thumbnail

  89. Family Tchentsov
    Family Tchentsov
    23 ditë më parë

    Pretty ironic that we need sunlight for healthy bones that are needed to shade the cells that create blood from sunlight.

  90. Ethel Ruthven
    Ethel Ruthven
    23 ditë më parë

    :( i have amutation in my bone marrow that causes me to have blood cancer. so ist not completely safe from mutations :(

  91. Demo Demo
    Demo Demo
    24 ditë më parë

    Bones are corral

  92. t9j6c6j51
    24 ditë më parë

    How do the blood cells get out of the bones?

  93. Mj Ananca
    Mj Ananca
    24 ditë më parë

    Ah yes Hank.

  94. Christian Indelicato
    Christian Indelicato
    24 ditë më parë

    I just pick the bones out before I eat the blood.

  95. Justin Lowe
    Justin Lowe
    24 ditë më parë

    The answer is obviously because skeletons are spooky...

  96. Geth
    24 ditë më parë

    Title: Why Do Our Bones Make Our Blood? Content: Blood is made in bone, sun bad.

  97. Faith Dorey
    Faith Dorey
    24 ditë më parë

    I usually dont have a problem with blood, horror movies used to be my fav until they got repetitive but this video is making me seriously nauseous and skin prickly

  98. Daksh Gharat
    Daksh Gharat
    24 ditë më parë

    Skin already pigmented that make me wonder why hide cells so deep inside🤔

  99. meurtri
    24 ditë më parë

    blood is gross and i feel weird knowing how much is moving around inside me.

  100. Ali
    24 ditë më parë

    Without bone, we can't get bone.