The eye is a complex optical and a very interesting sense organ. They are at work from the moment you wake up to the moment you close them to go to sleep! Eyes take in tons of information about the world around you; shapes, colors, movements, and more! Throughout reading chapter three, I have learned so much about the eye and how it works! There are three aspects to the perception of light. One of these aspects is brightness, which is determined on how high or low the wave actually is. When the wave is higher, the brighter the light becomes or appears to be. The length of the wave determines the color. The long wavelengths are originated at the red end of the visible spectrum. The shorter ones appear at the blue side. The last aspect to perception is saturation. This refers to the clarity of the color people observe. A less-saturated red may contain a mixture of wavelengths, but a highly saturated red will only include red wavelengths. The eye is like a camera. The external object is seen like the camera takes the picture of any object. Light enters through a small hole called the pupil. It changes size depending on the amount of light there is. Light waves are bent by the cornea and focus the image on the retina, which is like a camera film that consists of photoreceptor cells. Fovea is the central area of the retina, which is the greatest density of photoreceptors. The image formed on the retina is transmitted to the brain by the optic nerve. When the optic nerve leaves the eye, the blind spot is developed. The colored ring of the eye is the iris. This controls the size of the pupil and the amount of light entering the eye. The eye also has a focusing lens, which focuses the object and changes to do so. Rods and cones are located in the retina and are responsible for different aspects of vision. There about 120 million rods in each eye! They see only black, white, and shades of gray, because rods do not cause changes to wavelengths. Rods work well in limited light and allow the eyes to adapt to that low light. When the eye adapts from bright to dark light, dark adaption occurs. The opposite process occurs when going from dark to bright light. The light adaption uses cones, which adapt to the increased level of light a lot more quickly than the rods adapt to darkness. Our eyes work in such amazing ways, and there is so much more information about them! This is only some of the basics about the eyes that I learned about this unit. I love learning about the brain and how it works with the major sensory systems! Not only is this good information to know, but it will also help me in my future, as I become a nurse!