Bilog Cow Eye

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The Cow Eye Dissection Lab What are the structures of the mammalian eye and how do they function? The mammalian eye consists of many specialized cells and tissues that make up several different structures. The structures have certain functions and together, they form images that are interpreted by the brain. In this investigation, you identify the structures of a cow eye and learn their functions. Materials • Safety goggles • Preserved cow’s eye • Forceps • Dissection probes • Dissection scissors • Dissection tray • Vinyl or latex gloves • Apron or tee-shirt • Paper towels • Plastic trash bag External features of the eye A. Locate the cornea, sclera, and optic nerve. a. The white part of the eye, the sclera, is a tough, outer covering of the eyeball. The sclera gives the eye its shape and helps to protect the delicate inner parts. b. The blue covering over the front of the eye is the cornea. When the cow was alive, the cornea was clear. Together with the lens, the cornea refracts light and helps the eye to focus. The cornea gives a larger contribution to the total refraction than the lens. The curvature of the cornea is fixed while that of the lens is changeable. In your cow’s eye, the cornea may be cloudy. c. You may be able to look through the cornea and see the iris, the colored part of the eye, and the pupil, the dark oval in the middle of the iris. At the back of the eye is the optic nerve. To see the separate fibers that make up the optic nerve, pinch the nerve with a pair of scissors or your fingers. If you squeeze the optic nerve, you may get some white goop. That is myelin, the fatty layer that surrounds each fiber of the nerve. It is the nerve that transmits visual information from the eye to the brain. 1. List two functions of the sclera. •___________________________
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