How Much of Your Body Is New Every Year? | Compilation

31 Comments

1. What, not even if I have some fava beans and a nice Chianti? 😈🐑🐑🐑🤫

2. What about medication takers? Is my blood safe to donate if I'm on proscribed medication?

3. So glad sci show dropped the all caps style… used to never be able to read them

4. I wonder if the differentiation capabilities of menstrual mesenchymal stem cells play a role in teratoma development

5. So there's Lizzard Forrest Gump that "celebrated" new year with a legless Lizzard Sargeant Dan in a lab somewhere in the world? 😥

6. They should be paying for period blood. Not donating

7. Why not just pay people for embryos

8. The reason we are bad at regenerating lungs, is because for most of our evolution these injuries were almost entirely fatal. The same is true for brains and hearts etc. If an injury is always lethal, there is no selective pressure to regenerate it, and regenerative mechanisms get lost over time. The very fact we can live without a spleen is probably why it regenerates so well – it is non-essential but its presence confers a selective advantage. Likewise you wouldn't last a day without your liver, but you could last a long time with maybe 20% of your liver. You can also think about how a small animal like a salamander with a low metabolism and low flow blood rate would be more likely to survive losing a leg than a human or a frog. The salamander can still slide along on its belly, while the human will bleed out and the frog will become immediately vulnerable if it doesn't also bleed out – and surprise, salamanders regenerate legs, humans and adult frogs do not. Fish and salamanders can survive some pretty major heart injuries that would kill a human in seconds (probably because their metabolisms and oxygen flux are very low compared to mammals), AND they can regenerate their hearts. I don't think this is a coincidence. This sort of removal of selective pressure is commonly used to explain many phenomena in nature, such as the fact that many rodents age rapidly and are super vulnerable to cancer because most of them die to predation before these pressures become relevant.

   Of course the truth is way more complicated this. For example, traumatic liver and spleen injuries that don't also destroy other critical systems are pretty rare, suggesting that maybe these mechanisms are retained because of damage from disease or toxins, or because they are pleitropically linked to developmental and regenerative processes that are under stronger selective pressure. The liver, and other organs also adjust their size (slightly) to reflect demand as part of homeostasis, so regeneration of the liver and spleen might be linked to that. I'm just one regenerative biologist with an opinion, many others would disagree with me, and that's ok, it's how science should work.

   A bit of shameless self promotion, my thoughts on regenerative evolution are here:
   https://www.frontiersin.org/articles/10.3389/fcell.2023.1206157/full

   Some other citations:
   Why slow metabolism vertebrates are better at regeneration https://pubmed.ncbi.nlm.nih.gov/32914411/
   Regeneration of organs as an extension of homeostatic processes https://pubmed.ncbi.nlm.nih.gov/22542702/

9. Thanks for an incredible year of informative and wonderful videos in 2023! Eagerly looking forward to another year of amazing science content!

10. i have scars since 4 decades ago. the body doesn't regenerate whatsoever
    one burnt the size of a pea at the hand 3 decades ago, it has moved 1 inch and at this pace it would take 200 years to become new
    if this video was true, the yewish would see their point of their joystick repaired, but that's never happening.

11. i love my spleeeeen

12. Use my period blood. I have no use for them not now

13. I found it. Nevermind

14. Waiting for y'all to mention the NMN molecule…

15. Yes but… How much of your body is new every year?

16. The menstrual blood MSCs is very Bloodborne. So cool.

17. Shoot id love to donate menstral cells i cant donate blood because of how much i lose (i become anemic) so puting my hell towards a good use wpuld be nice

18. Extra spleen in humans? Is this a sci show video or blizzard animals video?

19. Eager beaver. On purpose. Gotta be. 😂

20. Eevee <3

21. Dental bills and the healthcare system in the US are a consequence of greed=capitalism.

22. Grey hair being caused by runway hydrogen peroxide could also be a part of why the stray grey/white hairs tend to have a different structure and be more brittle and less shiny/healthy/sleek in comparison to regular hair. It makes sense if you think of it as having literally been bleached in the same way that you'd bleach your hair to make it white at the hairdresser.

23. Now I don’t know who picked Flareon for that first video’s script or who called a period “monthly uteral redecorating”…

    But whether it’s one person or the whole team you have my heart.

24. "eager beaver" was not an accidental pun… ? Scishow comedy.

25. I started turning grey at 17. I liked how it was growing in, plus it has more body than the original.

26. I remember that 'multiple spleen' thing was in an episode of House.

27. Eager beaver? LOL!

28. I’m almost 80 but my hair stayed the same color as when I was 18. I’ve a few of those wild curly grey eyebrows and plenty of age-appropriate wrinkles but no grey hair. Weird.

29. Can I donate my own to make stem cells help my daughters, diabetes and her pancreas to make insulin?

30. It’s so remarkable with the woman’s body can do I mean if it can create a being inside and fully take care of it and grow it and birth it, and then also feed it and keep it alive afterwards it makes so much sense that whatever’s going on in the uterus Could do this

31. Stefan your biceps are magnificent.

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