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The Eye

The Eye. Splawn. Eye. The human eye is 1 inch in diameter. The Protected Eye. The eye is protected by the… Orbital cavity Eyebrows Eyelashes Eyelids. Tears. The eyes are continually bathed by tears secreted out of our lacrimal gland Tears cleanse and moisten. Lacrimal Ducts.

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The Eye

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  1. The Eye Splawn

  2. Eye • The human eye is 1 inch in diameter

  3. The Protected Eye • The eye is protected by the… • Orbital cavity • Eyebrows • Eyelashes • Eyelids

  4. Tears • The eyes are continually bathed by tears secreted out of our lacrimal gland • Tears cleanse and moisten

  5. Lacrimal Ducts • Tears flow across the into the lacrimal ducts • The lacrimal ducts empty tears into the nasal cavity

  6. Lubrication from eye lids • Along the border of the eyelid are glands that secrete an oily lubricant for the eyes • An infection here is called a stye

  7. Conjunctiva • A thin membrane that lines the eyelid and covers part of the eye • The conjunctiva secrete mucus which helps lubricate the eye

  8. The Wall of the Eye • The wall of the eye is made up of three layers • Sclera • Choroid • Retina

  9. Three wall layers

  10. Sclera • The outer layer of the wall of the eye • White of the eye • Tough strong protective layer that helps eye maintain shape • Muscles that move the eye in the socket are attached to the sclera

  11. Extrinsic Muscles • Those muscles attached to the sclera that are responsible for moving the eye within the orbital socket are called extrinsic muscles • 6 different extrinsic muscles the control different eye movements

  12. CLOSE YOUR EYES IF YOU DO NOT WANT TO SEE A REAL EYEBALL WITH REAL EXTRINSIC MUSCLES

  13. Cornea • In the front, center of the sclerotic coat lies a circular clear area called the cornea. • Window of the eye • Transparent to permit passage of light rays • Fed by lymph fluid as transparent due to lack of blood vessels

  14. Cornea (within the sclerotic coat) • Consist of 5 layers of flat cells arranged much like five sheets of glass • Cornea has pain and touch receptors which helps us protect our eyes

  15. Choroid Coat • The middle layer of the wall of the eye • Contains blood vessels that nourish the eye • Darker color to prevent light reflection that would distract from normal vision

  16. Pupil • In the front of the choroid coat there is a dark circular opening that allows for passage of light

  17. Iris • The pupil is surrounded by a colored muscular layer called the iris • Responsible for controlling the diameter and size of the pupil and the amount of light reaching the pupil • Muscles in the iris that control pupil size are called intrinsic muscles

  18. Pupil • Dilated by the contracting intrinsic muscles in dark light or when trying to see an object far away. • Constricted by bright light and close objects

  19. Lens • A crystalline (able to be seen through with clarity) structure located behind the iris and the pupil • Elastic, disc-shaped • Biconvex-curves outward on both sides • Posterior portion more curved that anterior surface • Flattens as we get older

  20. Lens • The lens is held in place by suspensory ligaments from a ciliary body • Ciliary body holds muscles that can change shape of lens • The loose their elasticity with age

  21. Lens • The lens changes shape to allow for near or distant vision • Accommodation

  22. Lens • The lens is situated between the ANTERIOR and POSTERIOR CHAMBERS • The anterior chamber is the space between the cornea and the crystalline lens • The posterior chamber is the space between the iris and the crystalline lens

  23. Lens • The anterior chamber is filled with aqueous humor, a watery fluid that helps maintains pressure in the eye. • The posterior chamber is filled with vitreous humor, jelly-like substance

  24. Retina • Inner-most or third coat of the eye • Between posterior chamber and choroid coat • Does not extend around front portion of eye • It is from this light-sensitive layer that light rays from an object form an image • After the image is focused on the retina, it travels to the optic nerve

  25. Lens • The lens will chan

  26. Positioning of the eye • The location of our eyes in front of the head helps us see stereoscopically • In three dimensions, 3-D • Length • Width • depth

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