Bio221TheSenses

Thefluidfromthecanalsdrainsintothelacrimalsacwhichdrai

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Unformatted text preview: s b. Lacrimal secretion ­ "tears"; a dilute salty solution that moistens and cleans the surface of the eye c. when the tears reach the medial edge of the eye, they enter holes called lacrimal punctum d. the tear fluid goes into the lacrimal punctum and into lacrimal canals e. the fluid from the canals drains into the lacrimal sac, which drains into nasal cavity 4. Extrinsic eye muscles a. control eye movement b. There are two basic eye movements i. saccades ­ small, jerky movements ii. scanning movements B. The Eye (eyeball) 1. Posterior eye a. the outer layer is sclera, which is white and opaque b. the middle layer is choroid; located beneath the sclera, it is dark brown and filled with blood vessels c the inner layer is the retina, which contains the nerve endings which register light i. cones ­ register color ii. rods ­ register B&W iii. blind spot ­ place where the retina enters the optic nerve; also called the optic disc iv. fovea centralis ­ pit in the back of the retina d. the posterior chamber of the eye is filled with vitreous humor (a clear jelly) 2. Front of the eye a. cornea ­ clear outside layer b. aqueous humor ­ clear jelly­like fluid between the cornea and the lens c. lens ­ focuses the light onto the retina d. ciliary bodies ­ hold the...
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This note was uploaded on 01/15/2014 for the course BIO 221 taught by Professor Profmendes during the Fall '13 term at SUNY Brockport.

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