Color Series | Christine Peters

Whitney Clay: Welcome to the West Valley College TEACH Center podcast.

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Whitney Clay: I'm Whitney Clay, Instructional Designer.

Michelle Francis: And I'm Michelle Francis, Professional Development Coordinator and Instructor in Child Studies.

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Michelle Francis: In this podcast, we discuss hot topics in teaching and learning. We interview educators about what they are doing in their fields, and we talk to learners about what inspires them.


Whitney Clay: Today, our guest is Professor Christine Peters, and she is a biology instructor. Our topic for today is color. And Christine, I wanted to ask you about how does color show up in biology?

Christine Peters: My specialty is I teach human anatomy and physiology, so I would say it's most fun. I think what I'm teaching physiology because it really gets you thinking about how our brains function and what is reality around us. I always start off this one lab where we are looking at our sensory system, asking that question of if a tree were to fall in a forest and no one was around to hear it. Would it make a sound? And the students are always perplexed. Of course, it would make a sound. And then when I am like, actually, it wouldn't, because sound is a perception that our brain manifest creates for us because the reality is the tree falls that makes vibrations. And so that then begins this little discussion of what is a perception and what is a stimuli that our bodies are sensitive to. And so color is sort of in that same realm is where we have this beginning discussion of how is it then that we use color? I ask students, know what colors do we see? And they list off all the colors of the rainbow and then they start adding in colors like pink and purple and violet. And a lot of them know already the sort of beginnings of how we see, like humans see visible light in the visible light spectrum. And I said, Well, how is it possible that you can see all the colors in the rainbow? Plus, we can see colors that are not in the rainbow. If what our eyes are seeing is visible light, a visible light doesn't have in it pink and magenta and those really fun colors. It's an interesting conversation that then begins how we really how our brains really work. And in our eyes, we have three cells that are photoreceptor so-called cones. The human eye has about six or seven million of them concentrated in the center of our field of view, and they are sensitive to just visible light, the light that has a particular wavelength that's in the visible light spectrum. And when light comes into our eye, if all three of them get stimulated at the same time, our brain interprets that energy, that light energy as white light. So if we stimulate all three consultancy, we see white, we stimulate one subpopulation of them. So, for example, the ones that are most sensitive to really low energy, which is red, then we see red. If our eyes are exposed to light that sees really high energy, then we see the violet like the the blues and violets.

Whitney Clay: So is it the same thing if there's a painting in a gallery and nobody's in there, there's no color in it?

Christine Peters: Well, it gives off wavelengths of energy, but the the way the brain perceives those wavelengths, it produces color.

Whitney Clay: Right. So there's no receiver. Then there's perceptions about happening.

Christine Peters: Correct. Yeah. If there's no way to interpret that information, then all it does is wavelengths of light. It's energy coming off of it.

Whitney Clay: So cool.

Christine Peters: It's really fun. You know, students always ask if you have only three cones, how do you see this amazing way of colors that if we only have three color receptors? And the answer is, it's really interesting the way that the brain differentially receives information from each of those that then creates a reality, which is why someone can look at a painting and see a color that looks blue and someone else can look at and say, Well, it looks green. The color that they see is how their brain is interpreting it.

Whitney Clay: So then that means color blindness – probably the majority of the population sees one way, and then there's a smaller amount of people that see in a different way. Can you explain that to me?

Christine Peters: Correct. So they do see color, but their brain is limited in the way that they can interpret. So we interpret with three sets of color receptors very similar to your TV screen. When you look at a TV like the old school TV, they had those big lights behind it. Right? You know, it's it's as though one of those is no longer working. So your ability to discriminate, the differences between those wavelengths of energy is now diminished, so they still see color, they just don't see the full array of color that a person who has three cones would see that are functional. The reality just looks different. And then we were talking the other day about that experiment. Oh yeah, it's exhausting their eyes and tell us about that So what kind of would be similar to colorblind in the sense that what you're doing is you are overstimulating One group of photo receptors, you can specifically stare at a particular color. So if you wanted to, you could stare at like a blue square. And if you were to stare at a blue square, you would basically fatigue those blue receptors. You would then move your gaze to a white screen, which is now giving you all the wavelengths, but it's not able to stimulate the blue cones. And so those blue receptors can't give the brain the information. And so the brain has created reality of what it sees minus that cones information. And so what you then see is yellow, which is really fun because the brain is trying to figure out what you're looking at minus that visual information, you're coming from those photoreceptors. I actually had a student. She was like, I was cleaning a pool, you know, pools They always have that aqua color. Looking at that aqua, you're actually going to call bleaching when that photo pigment turns over your bleaching, the blue and the green cones. And she said, when I was done clean, I got out of the pool and everything looked rose colored. Her view was all like pink. And that's because the brain was no longer receiving the information from the blue in the green. And so the whole world was just red. So much like was mentioned when you take a flash photo, if you stimulate all the cells and they don't have the ability to see anything. And so the absence of light is black, and that's why you see that black spot you should takes a few seconds and then that visual pigment is able to be gained its normal shape and you can see again.

Whitney Clay: So we were talking the other day also about your veins and how in textbooks and drawings, they always have red and blue. What's going on?

Christine Peters: That's probably the most confusing thing for our students as they come in, because every picture they probably seen about what blood that circulates in your body, you have arteries that are red and veins that are blue, and students should automatically assume that that's the color of your blood, especially because when you look at your skin, if you're fair skinned, it's much easier to see. You can see the vessels that are close to the skin surface and they look blue. So it sort of confirms the fact that, yes, my blood is blue when I tell them, no, it's not. Actually, they're shocked. It's interesting because it's again, >this whole idea of we're looking at wavelengths and energy of light and the brain creates and understand what it's seeing. Blood in your in your veins is actually like a dark, merlot color, like a red wine color when light travels through the skin. It then gets absorbed by the blood, the vessel, and then it reflects back and tries. What we see is actually what's not absorbed, but reflected. And so as that light hits the vessel and comes back, it has to travel back through the skin to come to our eyes. And the skin is really good at absorbing the lower energy of light, which is red. And so we don't see the red because the skin is like a filter. And so that gives the impression that the blood is actually that green kind of blue color because that's the color minus the red.

Whitney Clay: Does it look like – if you could, I don't know, get inside someone's vein, see in there – would it be the same color? Does it change color when you're bleeding?

Christine Peters: Well, I mean, many of us have had our blood drawn, and so you could see the blood as it comes out the coloration of blood. How red it is is dependent on how much oxygen is present. Oxygen is carried on a molecule called hemoglobin, which has iron. When iron oxidizes, that's called rust. Essentially, what happens is our blood is basically rusty when you need it, and it has that picture that bright red colored. Most of our blood is about 98-99 percent oxygenated. It's amazing how well our respiratory system works. When we allow that blood to travel in our body, our blood cells only really deliver about 15 to 20 percent of it to our body cells. It's usually about 75 percent oxygenated coming back. So it actually is a lot of oxygen, which is why it's not blue, and it's the reason why you can hold your breath for so long. It's amazing. You can hold your breath slowly for about four minutes before you see any real tissue damage.

Whitney Clay: I'm not going to try that experiment.

Christine Peters: Don't try.

Whitney Clay: Well, thank you so much. This was so fun and interesting to hear about color in your subject area.

Christine Peters: Yeah, fun to do.

Last Updated 5/20/22