VISION.The cornea and lens help produce a clear image of the visual world on the retina, the sheet of photoreceptors and neurons lining the back of the eye. As in a camera, the image on the retina is reversed: Objects to the right of the center project images to the left part of the retina and vice versa. The eye’s 125 million visual receptors — composed of rods and cones — turn light into electrical signals. Rods are most sensitive to dim light and do not convey the sense of color; cones work in bright light and are responsible for acute detail, black-and-white vision, and color vision. The human eye contains three types of cones that are sensitive to red, green, and blue but, in combination, convey information about all visible colors. Rods and cones connect with a middle cell layer and third cell layer (see inset, above). Light passes through these two layers before reaching the rods and cones. The two layers then receive signals from rods and cones before transmitting the signals onto the optic nerve, optic chiasm, lateral geniculate nucleus, and, finally, the visual cortex.
Author: Danny Version: 1 Language: English Category: Science Views: 145 Grades: 5-8
Picture: Brain Facts
Audio: Carlos Gardels: Bach's Book I: Prelude and Fugue No. 8 in E Flat Minor Source: http://freemusicarchive.org/music/Carlos_Gardels/Bachs_Book_I_Prelude_and_Fugue_No_8_in_E_Flat_Minor/Bach_-_Book_I_Prelude_and_Fugue_No_8_in_E_Flat_Minor_BWV_853_Prelude