According to one of the leading experts on the human circulatory system, blood flowing through veins is blue.

I’m not going to mention any names. All I’ll say is this: A person I know visited a major research center last year and saw a demonstration of organ removal and some other experimental stuff. A person also visiting asked the famous high-level researcher doing this work if blood was ever blue. What he said was not recorded in detail, but it was very much like this statement I found on the Internet:

… human blood is red as soon as it is oxygenated. Blue blood flows through veins back to the heart and lungs…..
[source: Some Guy on Yahoo Answers]

My friend was disturbed by this, as s/he had been teaching high school students for years that blood is not blue. Her understanding of the situation was that people thought blood was blue because standard anatomical drawings and models depict arteries as red and veins as blue, and because if you look at your veins they are blue. Obviously veins are not clear, but if you don’t think that out you might assume that you were seeing blue blood.

So another year goes by and the same thing happens again. Another visit to the operating theatre, another person asks about blue blood, another confirmation that blood is blue.

Now, I’ve seen both veins and arterial blood either seeping or gushing (respectively) out of various organisms, including humans and various other mammals, on a number of occasions. My grandmother used to spurt out blood now and then because of a condition she had. As I study hunting, I’ve observed lots of thrashing around blood spurting and seeping mammals. I’ve cut myself and I’ve donated blood. And so on.

I’ve never seen blue blood. I’ve seen darker red and lighter red blood. But never blue.

Now, going back to Yahoo Answers, which I am NOT recommending as a source for actual information, but which is a good source for what regular people sometimes think, we have the following three quotes:

Melissa says: When blood gets oxygen it turns red but in your veins it is blue just look at them.

Avondro says: Myth, it’s always red. It goes a darker red, purple-like (Some call it blue) when starved of Oxygen.

SS Agent Dick Wakka says: Somewhat true. Blood is very bright red when it is in the pulmonary vein in the lungs, when it is highly oxygenated. During it’s journey back to the heart after circulating through the body, it is a little blue when it is deoxygenated, but more of a maroon-blue mix. … This is the truth.

Agent Dick gives as a citation a “medical student.” Well, I’ve got a citation of a leading blood researcher at a major research institution that says blood is blue.

I think there are two things going on here, one having to do with physics and the other with culture.

The physical issue is about color. Is “purple” a kind of red, or is it a kind of blue? Beyond that, is blood that is “dark red” or “purple” really purple? Or is it dark red. See my point?

The cultural issue is that more surgeons and folks like that, for much of recent history, are males, and males are bad at color, on average. I’m not taking about color blindness, but rather, color indifference. See my point?

So here is what I think: If a person who says to themselves “Blood is blue in our veins” thinks either of the following:

… That blood is blue, like this:
i-c0070af494d0c462fc62da3b3d68124c-Untitled.jpg

… Or, that blood is “blue” in that you look at your veins and see blue, thus you are seeing your blue blood….

… Or, that you look at an anatomical chart and see the veins drawn in as blue, therefore the blood inside them is blue…

… then that person is laboring under a misconception.

If a person thinks that this “blue blood” is purple, then they may also be laboring under a misconception. The HTML Internet Purple looks like this:

i-c7a2aafde9de58fbb02ead3c451c0e15-purple.jpg

(I know, it looks dark blue to me as well.)

And the Pantone purple looks like this:

i-9c7d6257d9d14003b76501a87cf08294-pantonepurple.jpg

(I’ve never seen blood that looks like this)

Pantone Dark Red looks like this:

i-8f02ffce999f291926503ffed1e44caf-pantonedarkred.jpg

… very close to my blog’s colors, but not very much like the darker shades of blood that I’ve seen.

I think dark blood looks a little like this:

i-d4518e436c949c8d5f0607f94aeacbec-maybethisisblood.jpg

This color is 24% red, 2% green, 2% blue, but at a saturation of 92 with a color value of 24 and a hue of 0 degrees. Whatever that means.

(By the way if your computer’s video display is not set to a high value for number of colors shown, all of the above may look like only one or two colors. And, since all video screens are different, I might be seeing something different than you are…)

Anyway, the color that I personally think resembles blood in its darker state is not purple. It is red with a lot of darkness added to it. Or a lack of lightness, or whatever. But it is red.

Human, mammal, and many other organism’s blood is red. But finding out if this is “true” is like squeezing blood from a stone.

CLICK HERE for a PDF version of this post suitable for use in the classroom.

Please feel free to send a link to all your teacher friends so they know about it!!!! And, if there is something you’d like to see discussed, let me know.

Other items for teachers:

_____

Other posts of interest:

Also of interest: In Search of Sungudogo: A novel of adventure and mystery, which is also an alternative history of the Skeptics Movement.

Photo Credit: postbear via Compfight cc

Comments

  1. #1 The Excited Neuron
    September 1, 2010

    Nicely done. I’ll use this in class!

  2. #2 Amy M.
    September 1, 2010

    Downloading now.

  3. #3 Jim Thomerson
    September 1, 2010

    Once a month I get stuck in a vein, and my blood sucked into a evacuated test tube. Under the circumstance, the color is very much like your Pantone Dark Red.

  4. #4 Sam N
    September 1, 2010

    Shouldn’t a chemist somewhere be able to take a drawing of some human blood, add heparin, sequester the oxygen somehow, and give us a picture of oxygenated versus un-oxygenated blood?

  5. #6 Maria
    September 1, 2010

    This is funny! I’ve been living under the misconception that blood is in fact a dark purple blue (more purple burgundy?) in the veins but turns red (dark to light depending on the amount of blood) when exposed to air. And the internet has only cemented that notion with all it’s danged experts and citations.:P

  6. #7 Jared
    September 1, 2010

    Except those pesky arthropods with their hemocyanins…

  7. #8 Vince
    September 2, 2010

    That’s very good. Before I retired from teaching middle school science, kids would always tell me, “my teacher said you can’t see blood in your veins without oxygen, so how can you tell it’s not blue?” I would say “When I have to give a blood sample, I watch it in the tube. No oxygen, not blue. Try it.” Looks to me like your bottom color sample – not blue. Well done.

  8. #9 jaf
    September 2, 2010

    What Jared said.
    The color of the “blood” (or hemolymph) depends on what the heme is binding to.

    We dissected Manduca sexta larva (tobacco hornworm) last year and their hemolymph was a bluish green. Although apparently it will dye your hands a dark color if you get it on there and let it sit for a while.

  9. #10 zoop55
    September 3, 2010

    This is like elementary level anatomy info.

  10. #11 CGabe
    September 3, 2010

    Some species of crab have blue or green blood, due to having hemoglobin that’s based on copper instead of iron (same thing with Vulcans). (Would it then be cuproglobin?)

  11. #12 Jared
    September 4, 2010

    Hemocyanin…not hemoglobin…

  12. #13 Phillip T., M.D
    October 25, 2010

    Blood is never blue. I have yet to dissect a mammal or non-mammal with blue blood. Sometimes preparers inject cadavers with blue latex to help simplify studying, however naturally it is not possible.

  13. #14 Phillip T., M.D
    October 25, 2010

    Blood is never blue. I have yet to dissect a mammal or non-mammal with blue blood. Sometimes preparers inject cadavers with blue latex to help simplify studying, however naturally it is not possible. Crabs have hemolymph not blood

  14. #15 Phillip T, M.D
    October 25, 2010

    Hemolymph is found in animals with open circulatory systems(no vessels), blood is found in closed circulatory systems

  15. #16 Greg Laden
    October 25, 2010

    Phillip, good point about the hemolymph vs. blood. From now on I will use this tool to bludgeon my detractors such as Jaf who is always trying to show how she is smarter than me.

  16. #17 Erik
    January 14, 2011

    I cannot believe that people are actually arguing that blood is blue or red. This is very simple, and as someone who diagnoses and treats vein disease I should know, blood is always some type of red. Your veins looks blue under your skin, for the same reasons that the sky looks blue. It is a really cool concept called refraction. When you have your blood drawn for evaluation, we draw it from veins (generally). The blood is actually drawn into a device called a VacuTainer. There is a reason we use the prefix “VACU” and it is due to the fact that we will draw blood in a vacuum tube. The reason to put it into a vacuum is so we can test it as closely to the internal body as possible.

    So, when your blood is drawn, and it looks red; it still hasnt event hit O2 yet. Furthermore, to define veins as “deoxygenated” and arteries as “oxygenated” further means that our teachers have zero ability to open a book. Arteries carry blood away from the heart, and in fact the Pulmonary artery (which carries blood from the right ventricle to the lungs to get oxygen) is oxygen starved blood. Further, the Pulmonary Vein is oxygen rich and brings blood to the left atrium to goto the left ventricle and will distribute to the body through the Aortic Valve.

    Your veins do not look blue once we open the skin. Arteries and veins alike are white. Arteries are thicker and have pulsitile flow. Veins are thinner and have a more constant flow in a low pressure system.

    I have gone into many classrooms, and have realized that many teachers and even medical professionals, are teaching children radical information. Please do some simple research and you will find this true. If you are in a very powerful position of providing knowledge to our future physicians, nurses, educators, legislators, or even grocery worker- give them the correct information.

    Regards

  17. #18 pook
    April 1, 2011

    I have worked in labs for 12 yrs and come across A LOT of blood. And I draw blood and test it. I have never seen blue human blood, EVER. I have seen green blood many times, but this being from specimens taken from dead bodies. The green is along the lines of cooked spinach green to almost brown– a sludgy green color, not a grass green or pistachio green. It’s possible that blood that is contaminated with medications and whatnot may have another color than what it naturally would be.

    I have been told by dozens of young patients recently that “blood is blue, right?” or “I was told blood is blue, is the correct?” This while I am drawing them and pointing to them that what is coming from their veins is red. At first I was shocked, and had to question myself and what I’ve seen and what I’ve learned. thinking, why are they asking me this in this day and age? Because, it is red, whether it is dark red or light bright red, it’s red. RBCs are red. RBCs mixed with plasma, make a red colored liquid. Inside a living being, it is red. If it’s put in a tube, spun down and separated, the RBCs are still reddish.

    I was taught, that ages ago people had the misconseption that it was blue because it appears to be through the skin. But the truth is, deoxygenated (venous) blood appears as a darker red in humans, oxygenated (arterial) blood is brighter and lighter red. Under the skin, veins appear blue/green, but in fact carry blood that is deep red.

    I have to wonder why this sudden belief that blood is blue? Is it easier to teach children that venous blood is blue (even though it’s not) and arterial is red? At least they should make it a point to say, blood really isn’t blue. If anything, say it’s green to brown, but not blue.

  18. #19 Timberwoof
    June 29, 2011

    I recall a kid in school telling me that venous blood is in fact blue, but as soon as light shines on it it turns red. I asked him how that can possibly have been measured. He didn’t speak to me after that.

    (((
    “This color is 24% red, 2% green, 2% blue, but at a saturation of 92 with a color value of 24 and a hue of 0 degrees. Whatever that means.”

    RGB (along with a definition of what R, G, and B mean, which depends on your computer monitor’s phosphors or LEDs or whatever) is sufficient to specify the color. Saturation, color and hue are a transformation from a color space with cartesian coordinates to one with polar coordinates. Saturation is unevenness of colors: (0,255,0) is saturated green; (0,0,0), (128, 128, 128) (255,255,255) are not saturated at all black, gray, and white. Color value (or brightness) is the mean of R, G, and B. And the hue is some kind of arbitrary angle where 0°, 120°, and 240° are primary colors.

    So you don’t need HSB, and if the implementation of the hue transformation is wrong, you won’t get right results anyway. RGB is (mostly) enough.
    )))

  19. #20 don
    September 8, 2011

    Eric is right, blood is not blue in the body. All blood carries oxygen, venous blood just doesn’t carry as much as arterial blood. Actually the erythrocytes carry the oxygen as the hemoglobin in the cell is oxidized (Fe + O2) and the blood cell “rusts” which accounts for the very bright red that you see from a cut.
    Veins are “darker” because there is less oxygenated erythrocytes in the blood stream. Anyone who has donated or has had blood drawn has seen the color of this blood.
    Venous blood looks blue through the skin due because light must enter the epidermis, then the dermis, and then reflect back out to the surface. The various colors are transmitted/not transmitted and you see a blue shade look at blood through your skin. Remove the skin and veins would look white as it is surrounded by connective tissue. If you could see “into” the vein, the blood would look as it does during a blood draw.
    Since veins are very superficial in the arm, it is easy to see the veins.
    Try looking at them with a very intense light-say one of those garage halogen lights.
    You might see something different.

  20. #21 Jessica
    December 4, 2011

    Believe it or not this is a common misconception, even amongst the highly educated. I myself am a victim of this urban ledge. Granted I grew up in a public school system but an affluent one.

    Recently a friend of my brought up the question of venous blood being blue, because to her it seemed stupid that blood would ever be blue. My self & her boyfriend responded (like parrots) what we had been taught in “elementary anatomy” that De-oxidized blood was blue returning to the heart and after leaving the lungs was red (returning to the heart) before it was pumped back out to the body.

    We asked more friends, and all reiterated the same story. This is what we had been taught. This is what we had known to be true our entire lives. We are all from different schools, counties, and even states. We have a diverse set of knowledge, and levels of education including, doctorate, masters, BS, BA. Thus began the google search.

    My friend found many blog sites (such as this one), yahoo answers (which I noticed was reference here), and so on. However, being that the internet is what it is, you can find any answer you desire without it necessarily being true.

    Here I begin to see a problem. I am by no means in the medical field, but I do know how to research. So I began a quest to find the real truth to this.

    …drum roll…

    Blood is not blue, ever. Bright red to purple blue depending on your of personal perceptions of color. Much as was stated by Greg Laden with the color example. – Nice point, by the way.- However an accumulation of very logical arguments posted on the internet is not enough. I needed an peer-reviewed article. And tah-dah!

    http://www.imt.liu.se/edu/courses/TBMT36/pdf/blue.pdf

    A perfect citation supporting that venous/de-oxidized blood is dark red (of sorts), but a test as to the reason why the veins appear blue. I will continue to research and hopefully find other sources, because one article simply is not enough, but it is a start.

    I also now need to tell my friend that she was right. Darn.

    If anyone finds any good sources, I would love to see them. Thanks.

    Jes

  21. #22 Greg Laden
    December 4, 2011

    Thanks for that link! I’ve seen that (came across it while researching this post). It isn’t really about how blood is not blue, but it is very relevant to a likely source (or partial source) of the myth. The other, of course, being the anatomical drawings, which, in turn, almost certainly arise from the bluish nature of veins.

    The best myths are highly circular or even spiral like!

  22. #23 Doria
    January 9, 2012

    im only a highschool student . but I am an A plus student and am extremely interested in the human anatomy and physiology. I had been studying the human body since 7th grade and I’ve met TONS o people who think blood is blue. which that statement is very false. this article might just be my proof to everyone that blood really isn’t blue . thank you so much !

  23. #24 Doria
    January 9, 2012

    im only a highschool student . but I am an A plus student and am extremely interested in the human anatomy and physiology. I had been studying the human body since 7th grade and I’ve met TONS o people who think blood is blue. which that statement is very false. this article might just be my proof to everyone that blood really isn’t blue . thank you so much !

  24. #25 sujatha
    srilanka
    December 29, 2012

    my FBC test half the tube was filled with blue and the other half with red colour blood opinion was that its normal

  25. #26 IAN C.
    BURBANK CA
    May 14, 2013

    YOU SOUND LIKE A 9TH GRADE STUDENT

  26. #27 Jason
    Canada
    July 20, 2013

    Actually, Carbon Dioxide bound Hemoglobin is blue, there just exists no pure Carbon Dioxide bound Hemoglobin in the body, as blood is a complex mixture of many different things, and even de-oxygenated blood still contains oxygen in smaller amounts. The blue Carbon dioxide bound Hemoglobin mixed with the regular blood coloured Oxygen bound Hemoglobin, makes the dark colour we are referring to. If you want to take things even further, one could argue that blood is neither red nor blue inside the body because for one, there is little to no light inside the body, and Two, there is nobody to see the colour. “Colour” is the perception of different wavelengths of light by photo-receptive cells in the body. No light, no observing body, nothing is classed as being a “Colour”. That also has a little to do with Quantum Physics as well. go look of the Double slit experiment and how it pertains to the old Schrödinger’s Cat paradox.

  27. #28 Jason
    Canada
    July 20, 2013

    I guess i would have to retract the comment about there being no light inside the body. Light does penetrate the outer surface of our body, and the Body also produces light in a process known as Bio-Photonics or Bio-Electromagnetism. However, although the “Colour” of the compound could play more complex, atomic roles in the body, there is still no conscious observer, meaning there is not really a “Colour”.

  28. #29 Jason
    Canada
    July 20, 2013

    @ Doria. I’m sorry, but half the garbage you are fed in grade school is just that. Garbage. I completely broke away from the public educational system in the 10th grade, because i was being taught simpleton crap like what you are talking about right now. Chemically, blood bound to carbon dioxide is blue, end of story. I’ve had “Biology” teachers tell me carbon is toxic, complete combustion isn’t dependant on oxygen presence, that radiation at any dose is harmful, and that BT Toxin is completely safe. Wake up, for your own sake.

  29. #30 Jason
    Canada.
    July 20, 2013

    All these brainwashed morons repeating BS they read instead of looking into it, weather its “Peer reviewed” (which means nothing in the real world of science) or not, just goes to show you how dead real science really is. Moronic comments like “Not naturally possible”, “Never” and, “I’ve dissected animals and haven’t seen it” hold no scientific foundation. Clearly, none of you understand what “Blood” even is, or how “Colour” even works.

  30. #31 Mimi
    USA
    August 31, 2013

    Jason, you obviously think you know more than anyone else, even the experts! But you still don’t know the difference between ‘whether’ and weather’. Your choice of words also reflects your level of education. And please don’t blame your teachers and Public School system for your lack of proper education.

  31. #32 Shawn Anderson
    Delaware
    March 2, 2014

    I know this sounds extremely hard to believe…if it didn’t happen to me personally I would not believe it….believe it or not but I will swear on my mother’s grave…when I was about 8years old. I was riding my cousins bike with no shoes. Wasnt going very fast buxt the curbs on the side of the street were the square shaped one’s that kind of looklike a step. My toe scraped the curb and got jammed between the curb and my cousins bike pedal. My toe was gushing out blue blood the entire time. Blue blue….not people, not dark red , not red,….it was blue like smurf blue…all my cousins seen it , my brother and sister remember it….it was very scary as a little boy.knowing that blood was suppose to be red I thought something was wrong with me

  32. #33 Elizabeth
    USA
    June 3, 2014

    I see blood all day long because I am a dialysis nurse. When you have a patient with a central venous catheter, you access blood flow in the superior vena cava. This is a vein right above the entrance to the heart. The blood is darker red than arterial blood, which we access when the patient has an arterio-venous fistula. It never hits oxygen because it is taken out of the body, cleaned, and returned in a sterile closed system. Blood is always red or darker red.

Current ye@r *