7 ms·

Venous blood isn't blue.

zahlman 1y ago
> Veins close to the surface of the skin appear blue for a variety of reasons. The factors that contribute to this alteration of color perception are related to the light-scattering properties of the skin and the processing of visual input by the visual cortex, rather than the actual colour of the venous blood which is dark red.[6] Huh, thanks.
- thaumasiotes 1y ago
  As another commenter mentions, there is no blue food. (Though technically plants can be blue.) Eyes can't be blue either.
  - delecti 1y ago
    Human eyes aren't pigmented blue, but they are still blue.
    - thaumasiotes 1y ago
      Only in the sense that venous blood "is" blue.
      - delecti 1y ago
        We don't see the blood in veins, and it wouldn't be blue if we could, but I would agree that veins are blue.
  - bboygravity 1y ago
    Human blood can turn blue when consuming enough (collodial) silver? Like when rich people consumed food and beverages from pure silver plates (100's of years ago) their blood supposedly turned purple/blueish. Hence the term (at least in Dutch) that "he is of blue blood" = he rich af. Or that's all a myth. Not sure.
    - thaumasiotes 1y ago
      > Hence the term (at least in Dutch) that "he is of blue blood" = he rich af. This is usually said to refer to the fact that someone's skin is so pale you can see the veins through it. (Also, it refers to pedigree rather than wealth, in English...) I would expect silver to turn things black, not blue. (Although see https://en.wikipedia.org/wiki/Argyria https://en.wikipedia.org/wiki/Argyria )
      - goopypoop 1y ago
        They would hide from the sun to get extra veiny, because they could
        _9ptr 1y ago
        Like the programmers in our time
        thaumasiotes 1y ago
        Perhaps, but according to etymonline the term comes from Spain, where certain families described themselves as having "blue blood" to emphasize that they had no Moorish ancestry. The contrast being drawn isn't one between nobles and laborers. It's between indigenous nobles and intrusive nobles.
    - goopypoop 1y ago
      see also blue people - https://www.thecollector.com/blue-fugates-kentucky/ https://www.thecollector.com/blue-fugates-kentucky/ elevated methemoglobin in human blood causes brown blood causes blue skin
  - efavdb 1y ago
    Why not?
  - godelski 1y ago
    > Eyes can't be blue either. I get what you mean, but this is also like saying a butterfly doesn't have color. The blue in blue eyes (and green) is a structural property, not a pigment property. This is also why eye color changes for these people much more dramatically than people with darker colored eyes (see Hazel eyes). It's color caused by structure, but that doesn't make it not a color. A lot of things aren't going to "have color" if you use that definition. Including the sky...
  - jamessb 1y ago
    > there is no blue food Have you eveer seen a blueberry? Or a Concord grape? Or a damson plum?

> Veins close to the surface of the skin appear blue for a variety of reasons. The factors that contribute to this alteration of color perception are related to the light-scattering properties of the skin and the processing of visual input by the visual cortex, rather than the actual colour of the venous blood which is dark red.[6] Huh, thanks.

thaumasiotes 1y ago
As another commenter mentions, there is no blue food. (Though technically plants can be blue.) Eyes can't be blue either.
- delecti 1y ago
  Human eyes aren't pigmented blue, but they are still blue.
  - thaumasiotes 1y ago
    Only in the sense that venous blood "is" blue.
    - delecti 1y ago
      We don't see the blood in veins, and it wouldn't be blue if we could, but I would agree that veins are blue.
- bboygravity 1y ago
  Human blood can turn blue when consuming enough (collodial) silver? Like when rich people consumed food and beverages from pure silver plates (100's of years ago) their blood supposedly turned purple/blueish. Hence the term (at least in Dutch) that "he is of blue blood" = he rich af. Or that's all a myth. Not sure.
  - thaumasiotes 1y ago
    > Hence the term (at least in Dutch) that "he is of blue blood" = he rich af. This is usually said to refer to the fact that someone's skin is so pale you can see the veins through it. (Also, it refers to pedigree rather than wealth, in English...) I would expect silver to turn things black, not blue. (Although see https://en.wikipedia.org/wiki/Argyria https://en.wikipedia.org/wiki/Argyria )
    - goopypoop 1y ago
      They would hide from the sun to get extra veiny, because they could
      - _9ptr 1y ago
        Like the programmers in our time
      - thaumasiotes 1y ago
        Perhaps, but according to etymonline the term comes from Spain, where certain families described themselves as having "blue blood" to emphasize that they had no Moorish ancestry. The contrast being drawn isn't one between nobles and laborers. It's between indigenous nobles and intrusive nobles.
  - goopypoop 1y ago
    see also blue people - https://www.thecollector.com/blue-fugates-kentucky/ https://www.thecollector.com/blue-fugates-kentucky/ elevated methemoglobin in human blood causes brown blood causes blue skin
- efavdb 1y ago
  Why not?
- godelski 1y ago
  > Eyes can't be blue either. I get what you mean, but this is also like saying a butterfly doesn't have color. The blue in blue eyes (and green) is a structural property, not a pigment property. This is also why eye color changes for these people much more dramatically than people with darker colored eyes (see Hazel eyes). It's color caused by structure, but that doesn't make it not a color. A lot of things aren't going to "have color" if you use that definition. Including the sky...
- jamessb 1y ago
  > there is no blue food Have you eveer seen a blueberry? Or a Concord grape? Or a damson plum?