WEBVTT - BrainStuff Classics: Why Is Our Blood Red?

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<v Speaker 1>Welcome to brain Stuff production of I Heart Radio. Hey

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<v Speaker 1>brain Stuff. Lauren bog Obam here with another classic episode

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<v Speaker 1>from erstwhile host Christian Sagar. I admit we originally wanted

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<v Speaker 1>to do this episode Hey because it's interesting, but be

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<v Speaker 1>because we are fans of horror and we wanted to

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<v Speaker 1>demonstrate the episode on YouTube by dumping a bucket of

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<v Speaker 1>fake blood over my head Carry style if you happen

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<v Speaker 1>to look it up. I apologize in advance for what

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<v Speaker 1>counted as my acting ability at the time, but the

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<v Speaker 1>subject remains fascinating. Our blood is always read, even in

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<v Speaker 1>our veins when it looks blue. Here's why, Hey brain Stuff,

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<v Speaker 1>it's Christian Sager. Do you remember in the movie Carry

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<v Speaker 1>where they dumped pig blood on that girl at her prom? Well.

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<v Speaker 1>The Annals of Human Biology actually published an article in

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<v Speaker 1>two thousand twelve showing that humans are excellent detectors of

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<v Speaker 1>pig blood, but we are far less developed at detecting

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<v Speaker 1>human blood. They concluded that human blood has no specific

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<v Speaker 1>smell or appearance that triggers immediate recognition. So blood is

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<v Speaker 1>always red, right, But why does it have to be read?

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<v Speaker 1>Contrary to popular belief, it's not blue when it's in

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<v Speaker 1>our bodies, even when it's deoxygenated. But oxygen is part

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<v Speaker 1>of the color, along with the protein molecule hemoglobin that

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<v Speaker 1>attaches to oxygen it carries from the lungs two muscles

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<v Speaker 1>as blood gets pumped through the human body. And while

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<v Speaker 1>blood is always red, its shade depends on how much

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<v Speaker 1>oxygen it's carrying. For instance, when you cut a person's

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<v Speaker 1>arteries open, they bleed this really bright red blood because

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<v Speaker 1>of the complex formed between hemoglobin, iron, and lots of oxygen.

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<v Speaker 1>But if you look deeper into the circulatory system and

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<v Speaker 1>peered into a vein that was delivering all of its oxygen,

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<v Speaker 1>you would see that the blood is a deeper maroon color.

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<v Speaker 1>So veins they look blue or green mainly because of

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<v Speaker 1>skin and skin pigmentation plays a big role. Since everyone's

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<v Speaker 1>skin is a different color, our veins look different, especially

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<v Speaker 1>because the tissue above our veins scatters red light, but

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<v Speaker 1>let's blue light right on through. Even though veins are

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<v Speaker 1>a reddish brown, they appear to be blue from the outside.

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<v Speaker 1>So is the way human beings perceive color and other

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<v Speaker 1>factor here as well. Yes, researchers have shown that it

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<v Speaker 1>is partially an optical illusion. So light colored skin reflects

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<v Speaker 1>most light and blood absorbs most light, particularly dark deoxygenated blood.

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<v Speaker 1>It reflects a little blue and some red, But since

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<v Speaker 1>the skin surrounding the veins scatters and reflects a lot

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<v Speaker 1>of red light, the veins look way bluer in comparison.

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<v Speaker 1>The ratio is so skewed that it tricks the eye.

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<v Speaker 1>In fact, some animals actually need other colors, like slugs

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<v Speaker 1>and molluscs they believe blue. Today's episode was written by

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<v Speaker 1>Christian and produced by Tyler Clang. For more on this

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<v Speaker 1>and lots of other topics, visit how stuffworks dot com.

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<v Speaker 1>Brain Stuff is a production of iHeart Radio. For more

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