1. Special Senses
Visual Sense

2. Visual Sense
The Eye …
Video Clip

3. Visual Sense Eyes Eyelid Eyelashes Tarsal Glands Conjunctiva
Specialized organs designed for vision
Eyelid
Eyelashes
Tarsal Glands
Prevents eyelashes from sticking together
Lipid secretion
Conjunctiva
Mucous membrane covering inner surface of eyelid & surface of eye
Provides a fluid, which prevents friction

4. Visual Sense Nasolacrimal Duct Lacrimal Apparatus Lacrimal Puncta
Drains tears into nasal cavity
Lacrimal Apparatus
Produces tears in glands
Tears: Nutrients, Oxygen, Antibacterial enzymes (Lysozyme) & lubricants
Lacrimal Puncta
Pores that drain into medial canthus
Lacrimal Canaliculi
Collect tears from collect tears from lacrimal puncta
Lacrimal Sac
Collect tears from lacrimal canaliculi

5. Eye Anatomy Sclera Cornea 3 Layers: Iris Retina Choroid Pupil Sclera
Ciliary body
Lens
Choroid
Retina
3 Layers:
Retina
Choroid
Sclera

6. Eye Anatomy Video Clip Optic Nerve Optic Disk – Blind Spot
Vitreous Humor
Aqueous Humor
Retina contains photoreceptors:
Rods
Cones

7. Gaucoma Pressure builds up May cause damage to the Optic nerve
Aqueous humor is not drained effectively …

8. Eye Anatomy
Rods & Cones initiate the Nerve Impulse and send it towards the brain ….
Retina
Rods:
125 million
adapted to night vision
No color or detail
Cones:
6 million
Adapted for day vision
Provide color and detail
Bipolar cells – synapse with Rods & Cones
Ganglion Cells– synapse with Bipolar cells & merge to become optic nerve

9. Eye Anatomy Bipolar Cells Ganglion Cells Synapse with Rod & Cones
Synapse with Bipolar Cells
Merge to become Optic Nerve
Rods
Bipolar Cells
Ganglion Cells

10. Eye Anatomy Macula Fovea centralis Optic disk Concentration of cones
Visual image
Fovea centralis
High concentration of rods
Optic disk
Passes impulse on to Optic Chiasm

11. Visual Pigments – How do we actually see?
Visual pigments (in rods & cones) change shape when they absorb light
Rods -> pigment rhodopsin.
2 Proteins: rods & opsin
Rhodopsin changes shape due to light -> action potentials.
Cone cells contain other pigment molecules that are similar to rhodopsin.

12. Visual Pigments
Cones have proteins that are able to absorb 3 different wave length:
Blue
Green
Red
Combined those proteins give us Color Vision
Rhodopsin & similar Proteins are found in disks, which are frequently replaced.

13. Visual Pigments
Disk
Cone cell
Rhodopsin
Rod cell

14. Review - Eye Anatomy Bipolar Cells Ganglion Cells
Video Clip
Bipolar Cells
Synapse with Rod & Cones
Ganglion Cells
Synapse with Bipolar Cells
Merge to become Optic Nerve
Rods
Bipolar Cells
Optic Nerve
Impulse is passed on from Ganglion Cells to Optic Nerve to the Optic Chiasm
Ganglion Cells

15. Optic Chiasm –> 3 D- Vision