Our example tells us that in the following image, four important structures of the eye are labeled. Based on their location, identify which layer of the eyeball they are part of, then identify how each structure primarily interacts with light. And for interaction with light, we have 3 options. It says if the structure transmits light, mark it with a "t." If the structure controls light entering the eye, mark it with a "c." If the structure absorbs and responds to light, mark it with an "r."
Alright. So before we look at these very specific structures, let's remember those general layers that we learned: We had the fibrous layer, the vascular layer, the inner layer, and then filling up the eye with the clear optical components. Alright. So with that in mind, let's see what we got here. First up, we have the cornea, and we have this image of the eye here, and this arrow is pointing to the very front of the eye. So which layer is that? That outer very front layer. Well, that was the fibrous layer. The fibrous layer, remember, that's the entire outside of the eye, the cornea, the clear part in front, and the sclera, the white of the eye all around the back.
Alright. So how does the cornea interact with light? Well, as light hits the eye, it's got to go through the cornea. So I'm going to say the primary function or the primary way that the cornea interacts with light is to transmit light. I'm gonna mark it with a "t."
Next up, we have the iris. So we have arrows right here pointing to the iris right here. Do you remember which part of the eye or which layer of the eye the iris is part of? Well, that would be the vascular layer. The vascular layer, sometimes also called the uvea, right, had the blood vessels in it. But in the front here, it had that iris, which is the color of your eye, and its job is to block light coming in the eye. The only way that light can get in the eye is through the pupil, the hole in the middle of the iris. So thinking of it that way, how would you say that the iris interacts with light? Well, I would say that it controls the light entering the eye. I'm going to mark it with a "c."
Next up, we have the lens. Alright. The lens is right here. This structure right here in the eye. Do you remember which layer of the eye the lens is part of? Now, the lens is part of those clear components inside the eye, and we refer to those as the optical components. And now when you think of the lens, how would you say that it interacts with light? Does it transmit, control, or respond to light? Well, I'm going to actually mark it with two things, right, because the lens is definitely clear. So light goes through it, so it definitely transmits light. So I'm going to mark it with a "t," but it's also focusing the light. So when it focuses the light, I'm going to say it also sort of controls the light. It bends the light, so that you can focus it and have a clear image on the retina.
That brings us to the fovea centralis. The fovea centralis is going to be the center of the retina. So, the retina, what layer did we say the retina was? No. We said the retina was the inner layer. And how does the retina interact with light? Well, of these three options, there's one we haven't chosen. The retina responds. It absorbs and responds to the light, sends it in a message to your brain to perceive an image.
Okay. Now these are structures that are more detailed than you need to know quite yet. We're going to learn all of these in a lot more detail coming up. Right now, you just want to sort of organize this structure in your head and sort of think in grand schemes, how do these different things work and work with each other. Alright. More practice problems to follow. I'll see you there.