SENSORY SYSTEM FUNCTION OF THE EYE

EYE Protected by orbit, eyebrows, eyelashes, eyelids Lacrimal glands – tears empty into nasal cavity and clean the eyes Conjunctiva – secretes mucous to lubricate eyes

SCLERA and CORNEA Sclera: Tough coating, helps maintain shape of eye Extrinsic muscles - responsible for moving eye attached to sclera Cornea: Transparent so light rays can pass through

CHOROID COAT Middle layer, contains blood vessels Intrinsic muscles – change size of iris to control amount of light entering through pupil Pupil constricts: Gets smaller (in bright light) Pupil dilates Gets larger (in dark light)

LENS Where light rays are refracted Accommodation: Change in the shape of the lens to allow for near and distant vision

RETINA Light rays focus image on retina Image travels to the cerebral cortex via optic nerve Rods – sensitive to dim light Cones – sensitive to bright light and color Optic disc – on retina, known as blind spot, nerve fibers that form optic nerve

PATHWAY OF VISION Image travels through cornea, then pupil, through lens, light rays are bent or refracted, hits retina, picked up by rods and cones and carried to optic nerve, then to occipital lobe where the brain interprets image Figure 10-7 pg. 193