Human visual system Essay Example | Topics and Well Written Essays - 1250 words

Human visual system - Essay lessonHowever, for one to see, the human eye has to convert the visible light vital force into neural activity, a carry out that normally takes place in the retina part of the eye (Atchison and Smith 2000, P.11). The retina contains neurons, enable it to transduce light energy into neural activity. However, the process does not take place in a vacuum, rather with the help of rods and cones demonstrate in the retina according to Atchison and Smith (2000, P.11). Rods and cones argon photoreceptors that argon responsible for the conversion of visible light energy into neural activity (Bernstein et al. 2007, P.45). These photoreceptors usually contain chemicals, which are sensitive to light energy. As such, when light strikes the retina, the chemicals in the rods and cones immediately break apart, generating signals, which are relayed to the brain for interpretation. However, Bernstein (2010, p.91) notes that the process of rebuilding the chemicals broken apart in the rods and cones usually takes some time, which explain why a person usually find it hard seeing when incoming a dark room when coming from a bright light. Nonetheless, as one continues to stay in the dark, the rods quickly build up the chemicals thereby enabling the person to start seeing things normally. This process of adjusting to phantasm overtime is usually referred to as dark adaptation where one becomes approximately 10,000 times more light-sensitive after being in the darkness for quite awhile according to Atchison and Smith (2000, P.12). Cones, on the otherwise hand, contain three light-sensitive chemicals that help in determining the color being seen by an individual. Cones are usually found at the middle of the retina in an study known as the fovea. The fovea is the area where the incoming light is focused. Bernstein (2010, p.91) notes that the density of cones in the fovea differs from one person to another, which explains the differences in visual keen ness among different people. What is note that cones usually works best at high light intensities, where the ability to identify colors become active (Bernstein et al. 2007, P.46). For instance, it is possible for one to pick two different socks in a dark room thinking that they resemble each other and only learn later that the socks are actually different in color. From the retina, signals are transferred to the brain, where the information is translated before an individual is able to see something. However, as Bernstein (2010, p.91) points out, the eye does not just transfer the images it focused on the retina directly to the brain as this ordain make one see blurred pictures. Instead, the visual images are first sharpened by the eye, a function, which hugely depends on the interaction between the rods and cones, found in the retina of the human eye as noted by Atchison and Smith (2000, P.12). Bernstein (2010, p.91) reveals that rays of light usually pass through numerous stru ctures of the retina before striking the cones and rods. in one case the rods and cones have been struck, they generate signals that are again relayed back to the surface of retina, thereby allowing the ganglion cells and the bipolar cells to connect enabling the eye to start the process of information analysis. Bipolar cells are part of the neurons capable of sending every positive or negative signals