The Human Eye

2159 WordsOct 8, 19999 Pages
The Eye is the organ of sight. Eyes enable people to perform daily tasks and to learn about the world that surrounds them. Sight, or vision, is a rapidly occurring process that involves continuous interaction between the eye, the nervous system, and the brain. <br><br>When someone looks at an object, what he/she is really seeing is the light that the object reflects, or gives off. This reflected light passes through the lens and falls on to the retina of the eye. Here, the light induces nerve impulses that travel through the optic nerve to the brain, where it makes an image of the object, and then that image is passed on to muscles and glands.<br><br>The eye is well protected. It lies within a bony socket of the skull. The eyelids guard it…show more content…
The retina has several layers, one of which contains special cells named for their shapes - rods and cones. Light sensitive chemicals in the rods and cones react to specific wavelengths of light and trigger nerve impulses. These impulses are carried through the optic nerve to the visual center in the brain. Here, they are interpreted, and sight occurs.<br><br>Light must pass through the covering layers of the retina to reach the layer of rods and cones. There are about 75 to 150 million cones in the human retina. Rods do not detect lines, points, or color. They perceive only light and dark tones in an image. The sensitive rods can determine outlines of objects in almost complete darkness. They make it possible for people to see in darkness or at night. Cones are the keenest of the retina's receptor cells. They detect the fine lines and points of an image. The cones, for example, make it possible to read these words. There are three types of cones that receive color sensations. One type absorbs light best in wavelengths of blue-violet and another in wavelengths of green; a third is sensitive to wavelengths of yellow and red.<br><br><b>How Two Eyes Can Work Together</b><br>Most individuals use both eyes to see an object. This type of sensory perception is known as binocular vision. Thus, two images of the object are formed - one of the retina of each eye. Impulses from both images are sent to the brain. Through

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