Alright. So, like we talked about, the retina contains those photosensitive or light-sensitive cells. We have two types of photosensitive cells. The first type is called rods. If you're looking at our zoom-in of the retina here, the rods are all of these gray, literally rod-shaped cells, and rods are going to be responding to dim light.
So if you were in a dark or dimly-lit room your rods are going to be working really hard and they basically allow us to have monochromatic vision or our ability to see in kinds of blacks and whites and grays. This is why if you wake up in the middle of the night and your room is dark, everything almost looks like it's in grayscale. It's because in that very dimly-lit environment your rods are responding, and rods allow us to see in a monochromatic palette. Now, rods are located mainly along the periphery of our retina. If we're looking at our image here, the rods are going to be mainly located in these regions that I'm highlighting in purple.
We have relatively fewer of them located in the center of the retina and we have a lot of rods. Each of your eyes is going to have between 80 to 120 million of these cells, so they are very, very numerous. Now our other type of photosensitive cells are called cones. I'm going to pop off the screen just for a second so that you can see this a little bit better. But if we're looking at our image, our cones are these little rainbow colored cells there.
Again, they're literally going to be cone-shaped just like how our rods are rod-shaped, and cones respond to bright light. Anytime you are in a well-lit environment, your cones are going to be working really hard and cones basically give us color vision. So cones allow us to see in color. Now cones are going to be located mainly in the center of our retina so they are very densely packed right into the center of the retina and then we have relatively fewer of them along the periphery.
So basically the opposite of what we see with rods. And compared to rods, we have relatively few cones. Each eye has between 5 to 7 million cones. And again, they're going to be very densely packed into the center of the retina. Now, speaking of the center of the retina, as I mentioned previously, that is a very important part of the eye.
This region is actually called the fovea. The fovea, which you can see here, we kind of illustrated it with like a little bump in the retina. The fovea is the center of our retina and because of that, it's going to contain a lot of cones of course because cones are located mainly in the center. And the fovea has very high visual acuity. It's basically the region of our retina where vision is the sharpest.
So that's why every time I was kind of tracing the path of light as it entered the eye, I was always having it hit, like, right there in the center of the retina because we want light to be hitting there for optimal visual acuity. Alright? So that is the fovea. Now we know we're talking about these photosensitive cells responding to light, but that signal has to actually get to our brain somehow. Right?
So, it's going to be getting to our brain via the optic nerve, but that is actually going to create a blind spot in our eye. So our blind spot is basically going to be the location where the optic nerve leaves the eye, and in this location because we have the optic nerve literally exiting the eyeball, we have no receptors in that region. So we have no rods and no cones in that area, and so because of that, we literally can't see. It's a little tiny blind spot in our eye.
Now, you basically never notice this blind spot and it rarely causes problems. Your eye does certain things to kind of make up for it and your brain does as well. So, we basically never notice it, but it is there, which is kind of cool to think about. So just to kind of sum everything up, just as a kind of memory tool, It might be helpful to think about how cones see in color. Cones are near the center, so all those kind of c words going together, and they are scarce.
I know scarce is a bit of a stretch, but think of that kind of c sound that we have going on there. So cones that see in color, they are in the center and they are scarce. And if you know what cones do, you know that rods are basically the opposite of all of those things. Right? Alright.
So those are our photosensitive cells, and I will see you guys in our next video. Bye bye.