1. The Eye and Sight

2. Orbital Cavity– Overview
Structures
Eye
Eye Lids
Lacrimal Apparatus
Extrinsic Muscles
Functions
vision
protection
lubrication, kill bacteria
eye movement and focus

3. Eye Structure Regions of the eye Outer Layer Inner Layer
Anterior Cavity
Ciliary Body
Posterior Cavity

4. Eye Regions – Outer Layer
Structures
Functions
Cornea (transparent tissue)
Sclera (white tissue)
Optic Nerve
Protection, focus light entering the eye
Protection, site of attachment of extrinsic muscles
Carry impulses from the eye to the brain

5. Eye Regions – Anterior Cavity
Structures
Functions
Aqueous Humor
Iris
Pupil
Transports nutrients, maintains eye shape
Controls amount of light entering the eye
Allows light to enter the eye
pupil contraction and dilation video

6. Eye Regions – Ciliary Body
Structures
Functions
Lens
Suspensory Ligaments and Ciliary Muscles
Focus light entering the eye
Hold lens and adjust its shape
video of ciliary body changing lens shape

7. Eye Regions – Posterior Cavity
Structures
Functions
Vitreous Humor
Retina (cones and rods)
Choroid Coat
Optic Disk
Maintain eye shape
Receive light and convert it into nerve impulses
Nourish the retina, absorb light
Point of attachment of retina and optic nerve

8. Vision– Light Refraction
Light waves change speed and direction as they pass through media of different optical densities
Refraction: bending of light waves as they pass through a lens.

9. Vision- Pathways Object reflects light Light through aqueous humor
Cornea refracts light
Light focused on the retina. Photoreceptors convert light into nerve impulse
Iris adjusts amount of light entering the eye. Light enters through the pupil.
Light through vitreous humor
Ciliary body adjusts lens shape. Lens refracts light

10. Visual Nerve Pathways Nerve impulses transmitted by the optic nerve
Cross over at the optic chiasma
Carried to the visual cortex in the occipital lobe
visual cortex interprets impulse as image: sight!

11. Vision: Photoreceptors
Photoreceptors on the retina include:
Cones: sensitive to different wavelengths of light. Allow color vision.
Rods: sensitive to light/dark. Allow black and white vision and night vision.