 Hey everybody Dr. O here and this is where we're going to cover your two types of photoreceptors your rods and cones. So as you can see the bottom half of them looks the same so it makes them different as what's called their outer segment. So the rod in its outer segment contains the photosensitive pigment rhodopsin and your cones are each going to contain photosensitive pigments called opsins and they're going to differ based on their wavelength. We'll show you that. So your cones they can they perceive the three different primary colors red green and blue. We'll show that a little bit more here. So each of these opsins are going to be sensitive to a limited wavelength of light. So you see rods there the peak sensitivity of that rhodopsin is going to be 498 nanometers for your three color opsins. Opsins for red it's going to be 564 nanometers for green 534 and then for blue it's going to be 420 nanometers. So each of these cones can see about a hundred shades of color that are that are within those wavelength ranges and because we have three so a hundred times a hundred times a hundred. That means that normal human eyes can register about a million different colors. There are some people that can see more and then obviously if your color blind and you're missing one or more of these cones you would be able to see a lot less. Some people see the whole world basically in grayscale which is what your what your rods would be able to see. So rods they do they do not register you know these different colors but they're very sensitive to vision in low light. So your rods are really good in low light at showing you the world in grayscale. You can still see diffuse edges. You can still see movement but you're not going to see much of that fine detail. So if you're in the dark looking at something and you think you see color it's not it's actually your brain is relying on memories of what color you think things are. It's pretty cool. So we do kind of see the world in grayscale. So here we see that we have your photoreceptors your rods and cones and they're connected to those special sense neurons the bipolar neurons that are connected to ganglion cells. So one last thing to say about rods and cones because the actual ganglion cells that monitor them are different too. So the ganglion cells that monitor your rods are called m cells or magno cells. They have they're large they they they so they they're not very localized which means you just get general information about the general form of something motion shadows but not clear vision. The ganglion cells that are linked to your cones are going to be called p cells or parvo cells. They have basically smaller areas they're responsible for. There's more of them. You're going to get a lot more precise information about fine detail edges and then obviously the color we talked about. So if you want to see something turn the lights on and look at it right that's the way you look at things. So your rods are really good in low light environments and with peripheral vision but if you really want to look at something or see something look right at it and make sure you have plenty of light. All right that's your photoreceptors your rods and cones next we'll cover the entire visual physiology process. I hope this helps have a wonderful day be blessed.