Sophia hosts politics section editor Kalen Luciano to answer his question – why do hickeys change colors?
Sophia Lo: Hello, hello and welcome to the first episode of North by Northwestern’s new Science and Tech podcast, Solved by Science. I'm your host for today. I'm Sophia, and I'm the Science and Tech editor for NBN, and this is the sections’ new podcast. It's called Solved by Science because different people ask me questions that I answer with science. And today's guest with me is Kalen. Yay!
Kalen Luciano: Yay! Hi, I'm Kalen. I'm the politics section editor for NBN, and I'm on here to ask a very important question that I've been thinking about a lot lately.
Sophia: Great. What's your question, Kalen?
Kalen: Okay, so to give you some context of why I developed this question, I saw someone in my dorm who had a little bruise on their neck, and when I first saw it, it looked like a typical bruise, but after a couple of days it started to change colors and I was curious as to why that was so it went from like, you know a purplish color to like yellow, and I was like “Is your skin like falling off? Are you a zombie?” Like I was really concerned and apparently it's a typical thing, but I don't really know why that is. So why do your hickeys change colors?
Sophia: Great question, Kalen. So you touched on the first part. Hickeys are bruises, and bruises change colors. So this happens because the capillaries, which are a type of blood vessel that carries red blood cells, are crushed by some sort of trauma or like some sort of injury. So when you bump your elbow on the table, that's the trauma. When someone sucks on your neck and gives you a hickey, that's the trauma. So broken capillaries means that the red blood cells sort of come out, but since a bruise doesn't fully break the skin, the blood is trapped under your skin. So that's why I immediately after your hickey or bruise, we don't know how you got that.
Kalen: It wasn't me. It was someone else in the dorm.
Sophia: Glad you made that clear, but for the listeners, you, we don't know how you got that. It could be anything.
Sophia: So that's why a bruise will look red, blue or dark purple just because the blood is fresh.
Kalen: Okay, but why if blood is like supposed to be red, why does it show up here purple underneath the skin if it's just blood that's like trapped underneath the skin?
Sophia: Before we talk about that, let's talk about why is blood red? So blood is red because of a protein found inside red blood cells called hemoglobin. So hemoglobin is a protein that's found in your red blood cells, and its job is to carry oxygen from your lungs to the body and the different tissues in your body. So hemoglobin is made up of different things, so one of their subunits is called a heme that's why we get the name hemoglobin. So hemes bind to iron in your blood and then the iron binds to oxygen, so the interaction between hemes and oxygen is what gives blood its red color.
Kalen: So is it purple underneath the skin because oxygen doesn't touch it or like what's up with that?
Sophia: It kind of turns blue and purple. That's your sort of the initial discoloration when you get the bruise, and at that stage, macrophages are beginning to break down the blood cells, and macrophages are white blood cells which are part of the immune system, and the purple part is sort of like the blood losing the oxygen and part of the initial swelling that comes along with the bruise.
Kalen: So it is purple underneath, and like actually purple.
Sophia: Yes, it is purple. All of these are like the actual colors. It's sort of like the chemical process which we'll get more into. Side note: blood is never blue. Kalen, do you want to talk a little bit about why I wanted to mention that?
Kalen: Yeah, I am not gonna lie. When we looked into this question to begin with, I really thought the blood was blue underneath the skin because like when you look at your veins, it's blue. And so yeah, my bad.
Sophia: That's actually a pretty common misconception, but we'll talk about that a little bit. This is more about light and wavelengths and physics and optics and all the things. I'm not good at...
Kalen: Wow, exciting.
Sophia: Really thrilling stuff. So essentially some wavelengths are able to penetrate the skin better than others. So red light kind of goes in deeper, I guess, and then blue light kind of hits your veins. It doesn't disperse in the same way. And essentially the blue light is reflected back to your eye. So it's a common misconception that the veins are blue blood because it's been deoxygenated, but it isn't. Have you ever gotten your blood drawn?
Kalen: Yes, but I do not look at the the blood being drawn because I'm scared of needles. So I always look away, and I do not look at the place where they're drawing blood until the person places a BAND-AID on it. So I do not see the process whatsoever.
Sophia: Okay, but have you seen the blood that comes out?
Kalen: I refuse to look at anything near their equipment, like I do not want to look at it. I just want to be out of there.
Sophia: So even when they take the little, tube you've never looked know.
Kalen: Nope, nope.
Sophia: Okay, so I guess you wouldn't know, but that blood does come from your veins and it's not blue. It's still red. It is a darker red.
Kalen: I'm literally uncomfortable just thinking about the fact that there's a tube that was because of the blood in my veins that they drew out, like that really really makes me so uncomfortable. Continue.
Sophia: Okay, that's okay. My point was that that blood does come from your veins and it's not blue, but fun fact and another side note off this side note. There are some animals that have blue blood, like octopi! And that's because of a chemical called hemocyanin in their blood. So instead of iron in the blood, there's copper in the blood, and that's one of the big differences.
Kalen: You know, I have a side note about this.
Sophia: You do?
Kalen: Have you ever had octopus?
Sophia: Like eaten it?
Sophia: Yes, I’m Asian, of course.
Kalen: One of my favorite meals. Continue.
Sophia: I don't, no one has a meal of just octopus.
Kalen: Okay, well, it's one of my favorite things that I've ever eaten.
Sophia: Takoyaki from Table to Stix, that's where it's at. Anyway, back to bruises! I guess kind of the purple part of the bruise, and then next is usually the green.
Kalen: Oh, I didn't even notice a green phase of this.
Sophia: Well, you are colorblind.
Kalen: This is true, and I was attacked for it a lot this week with a lot of memes, but it's fine. We're moving on, we're moving past it. Anyway, why does it turn from purple to green?
Kalen: It takes seven days for the bruise to leave? Oh my god!
Sophia: The bruise isn’t fully gone yet. Remember, I did say it takes about two weeks, that’s 14…
Kalen: It takes two weeks to get a bruise to, like, get rid of it?
Sophia: Do you want to test it? I can punch you real fast.
Kalen: No, no, it’s okay, it’s okay. Just a yikes for that person that had a bruise on their neck. A real yikes.
Sophia: So you might have not noticed it's a greenish color because that's pretty short. It also sort of blends into the yellow pretty well, but basically, your body is just a reabsorbing all of that stuff, remember like since the skin never really breaks, nothing ever leaves. So your body is reabsorbing blood, it's reabsorbing the hemoglobin and iron and all that other stuff. So during this process, it does kind of turn green. So that's the leftover hemoglobin and that is then turned into a substance called biliverdin and then the next color it goes is yellow so basically you're hitting all the colors of the rainbow. We love!
Kalen: Wow, we love some gay pride!
Sophia: And that's called bilirubin that's sort of the last phase, and the yellow is when it sort of gradually fades. That's probably why you don't think that bruises take two weeks to heal because you know by the time it turns yellow it sort of blends into the skin, and then the person doesn't need to worry about the hickey on their neck.
Kalen: Very nice. Okay, so that's great and all. I understand why they change colors but why do some people get hickeys or bruises more easily than others?
Sophia: So there's a couple different reasons for this. So people with softer skin and softer tissue tend to bruise more easily. And as people get older, your skin gets thinner and blood vessels get a little more fragile. So that's another reason they might break a little more easily. So some people also bruise more easily because of different medications they're taking, or different medical conditions. Vitamin K plays a role in blood clotting, and a deficiency in vitamin K could be a cause for more bruises, but also I am not a doctor. I'm not qualified to diagnose this. Am I gonna take my vitamin K? Maybe, I have multivitamins I haven't taken in a few days.
Kalen: Are you worried about bruising?
Sophia: No, I don't bruise at all.
Kalen: Really. I don't bruise easily. I’ve fallen down a lot of times.
Kalen: Oh, yeah?
Kalen: Like the 20 times you fell down the mountain, you didn't bruise at all from that?
Sophia: I don't think so. For those who don't know, Kalen can tell the story because it's one of his favorites.
Kalen: Over spring break, Sophia and I went to the Smoky Mountains in Tennessee. And on one of the days, we hiked up the mountain, and it was icy because the altitude was so high. On the way down, I held her hand for the whole time, and yet she still fell over 20 times! And at some point, I was really convinced that maybe she was just giving up. She had the look of defeat in her eyes. She would start to slip it would not even try to stay off anymore and just slam down.
Sophia: Okay, in my defense, it was March. I did not expect there would be ice on the mountain. So I wear sneakers.
Kalen: We’re Chicago, you should just be ready for anything at this point. Yes, it was in Tennessee, but you should just be ready for anything.
Sophia: Okay, look at my boots right now. These are my boots, and they still have horrible traction. I don't go outside, Kalen. But point is, I fell down out about 20 times, and I was sore, but I'm pretty sure I did not bruise.
Kalen: That's because you have enough vitamin K that you don't have to worry about bruising
Sophia: Or maybe I just have really strong skin.
Kalen: Maybe. How do you determine like whether you have stronger skin? What scientific thing is behind that?
Sophia: So basically as I mentioned before, as you get older, your skin does get thinner. So there's this part of the skin. There's a specific section called the dermis and that part sort of preserves…
Kalen: Is that the top layer of the skin?
Sophia: Yeah, it should be in the middle layer because the top is the epidermis and then you have the dermis and then you have the hypodermis which is the deepest part of skin.
Kalen: So much dermis, we love.
Sophia: Yeah. Probably a Latin root. I take Latin, I should know. Do I? Nope! So the dermis is the thickest part of your skin and there’s something in it called collagen and elastin. So as you get older, you aren’t able to produce collagen as well. So sometimes that's part of what causes your skin to become thinner.
Sophia: Okay, so just to recap back to the original question: why do hickeys change colors? So basically, a hickey goes from a reddish to a blue dark purple to pale green and then sort of a yellow or brownish color. That's for all bruises, just because that's sort of your body's way of healing itself after the capillaries break under the skin and the blood comes out. Hope you learned something! All of the references are linked in the transcript, so check that down below. Our intro and outro music is “Eve” by Dee Yan-Key, which is under a Creative Commons attribution license.
Kalen: I'm Kalen.
Sophia: And I'm Sophia, and see you next time. This is NBN Audio.