Science Q&A

From my ThinkGeek newsletter, the greatest bit of science Q&A I think I have ever read:

Dear Timmy,

When I drink grape juice, and then I go pee, where does all the purple go?

Brandon
Toronto, Ontario, Canada, The blue and green planet


Dear Brandon,

I'm surprised no one has ever talked to you about this before ... what ever are they teaching you in high school biology these days? Basically, the process is very simple. The "purple", as you call it (the technical term would be "tannins"), is processed by your kidneys and broken down into its constituent reds and blues. The reds are injected into your arteries, which is what makes your blood red, and the blues are injected into your veins, which is why your veins appear blue under your skin. What's left over is basically white grape juice, which as we all know is pretty much the right color already.

As a side note, have you ever wondered why the blood in your veins will appear red once its outside your body, even though it was blue when it was under your skin? Well, the answer comes from a branch of physics called optics, which studies things like colors. Red, as it turns out, is water soluble, so the blood absorbs it. Blue, however, floats on top of the blood and ends up coating the inner walls of the veins. When you cut into a vein, only the red actually escapes.

Isn't science wonderful (and sarcastic)?

-- Timmy