our fourth learning objective is to describe the role of rods and cones in Vision rods and cones are the two different types of photo receptors which are the specialized receptors which detect light so in this image here we have a section of the retina with a rod and a cone highlighted the retinal pigment epithelium is up the top here which is the very back of the eye and the light comes through in this direction when the light hits that retinol pigment epithelium it's absorbed by melanin and this causes a receptor potential or a graded potential to occur in the outer segments of our rods and our cones in case you hadn't already guessed our rods and our cones are named because of their shape so rods are the more numerous photo receptor and you can see that in this representative image down the bottom rods operate in dim light so at night or when you walk into a dark room without a light on and they can't discriminate color so you know when you walk outside at night and it's dark and you can see Shadows or outlines of things but it's all gray or black and white now as we very briefly mentioned earlier rods and cones feed into bipolar cells and then gangan cells before those gangan cells converge and exit the eye through the optic nerve with rods several rods will feed into a small number of bipolar cells before they feed into a single gangan cell for this reason rods produce quite a fuzzy and indistinct image because the image being received by the brain is a bit of an average of all of the stimuli coming from those multiple Rod cells with our cones they are less numerous and in contrast to rods they operate in bright light and can discriminate between color we actually have specific cones for red green and blue colors as all of these colors are represented by different wavelengths of light and therefore can be detected by a specific receptor or a specific cone the variation that we can see in color so we don't only see in red blue and green comes from a combination of these receptors being activated also in contrast to rods one single cone feeds into a single bipolar cell and a single gangan cell and because there is no fusing or mushing together of images from different stimuli the vision that we get from cones is really sharp and detailed and of a high resolution