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The human eye, unlike invertebrates is capable of detecting many variations of colors as well as form images of objects that are located at a distance. It is also capable of responding to as few as a single photon of light
The human eye, unlike invertebrates is capable of detecting many variations of colors as well as form images of objects that are located at a distance. It is also capable of responding to as few as a single photon of light (Campbell, 1999). The basic parts of the eye, particularly, the iris, lens, pupil and cornea, function to manipulate and focus the light to the retina, which houses the photoreceptor cells Cornea is located at the front of the eye and functions by getting light into the eye, acting as a fixed lens; the iris changes size to regulate the amount of light that enters the pupil. The photoreceptors function by receiving information transmitted in the form of light. This information is then transferred to the optic nerves, to the brain through the optic disc, the spot on the lower outside of the retina.The eye has two major cavities filled with clear water liquid. One, is located between the lens and the cornea, which is filled by the aqueous humor. The other is located behind the lens within the eyeball itself, just touching the retina. This is filled by the jellylike vitreous humour which constitutes the bulk of the eye. These liquids function as liquid lenses. Similar to the cornea and most parts of the eye, their function is to focus the light into the retina as liquid lenses. As said earlier, the retina houses the photoreceptors so that information can then be transferred to the brain for interpretation (Vander, et. Al, 2001). ...
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