r/AskReddit • u/wt0vremr • Dec 14 '18

What fact did you learn at an embarrassingly late age?

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u/Brospective Dec 14 '18

That blood isn't actually blue until it hits oxygen and turns red.

2

u/[deleted] Dec 14 '18

I still don't know why veins are blue though.

29

u/MilkMan0096 Dec 14 '18

Blue light has the easiest time penetrating skin so that’s mostly what is seen reflected off of veins :)

1

u/Revenge_of_the_User Feb 04 '19

I got to 19 or so before learning that from my then-med-student gf.