BOVINE EYE DISSECTION INTRO

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BOVINE EYE DISSECTION INTRO
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Can humans or non-human animals see in the dark?
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NOYou need light!
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• Light?
• Waves of electromagnetic energy
• Photons discrete particles of energy
• ?Travel in space at high speeds (186,000/second!)
• ?Measure in length nanometers (billionth of a
  meter)

So, we call these wavelenths Visable to humans ?
380 760 nm
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Visible Spectrum of Wavelength - Humans
snakes see infrared (too long for humans)
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1. Sclera covering of eye
Anatomy of the Eye
2. Cornea covers iris pupil focusing begins
(80)
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2.
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3. Anterior Chamber (aqueous) clear fluid?
nutrients/shape
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3.
4. Iris muscle, control of light intake, color
(melanin)
5. Pupil hole in iris --dilates/contract based
on available light
1.
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6. Lens adjusts the eyes focus (20)
accomodation
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7. Vitreous Humor gives eyeball shape
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8. retina transduction rods cones
10. Optic Nerve
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9. Fovea acuity, cones
11. choroid
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Anatomy of the Eye
Light entering the eye
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Normal Vision
Problem in lens ? Cataracts protein clumping
together
Problem in the macula (fovea) Macular
Degeneration loss of acuity and center vision
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The visual system is like a Camera
Lens of the eye inverts the visual image
Upper half of visual field projects onto the
ventral portion of the retina Lower half of
visual field projects to the dorsal portion of
the retina Thank God (or whomever) that the
visual cortex inverts it back to its original
orientation!
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Anatomy of the Eye - Retina
Retina Photoreceptors Transduction of light
Into electrical chemical Message Instead of NT
Binding to receptor Light cause cascade of
Intercellular messages
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Ganglion Cell Axons form optic nerve
Cell Layers in the Retina
notice anything funky about the set up?
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• Duplexity Theory
• Rods (scotopic)
• -responsible for night vision
• very sensitive to light (low levels)
• found in the periphery of retina
• more than cones
• Provide monochromatic info
• (Achromatic)
• - Provides poor acuity
• Night blindness
• Cones (photopic)
• -responsible for day vision (sensitive to
  
• mod-hi light)
• - found in fovea
• - provides greater acuity
• - trichromatic color vision
• - legally blind (day blindness)

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Anatomy of the Eye Blind Spot
blind spot
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The blind Spot
1 million nerve fibers
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IPSI CONTRALATERAL PATHWAYS
Optic Tract 1/2 axons go to right side of the
brain 1/2 go to left side of brain Not the same
in all animals depending on location of
eyes Ex Rabbits Guinea Pigs
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How does the signal get to the Visual
Cortex? VIA the Retinal Ganglion Cell Axons


OPTIC TRACT
OPTIC TRACT
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Damage to the optic nerve Glaucoma
Glaucoma problem in the Anterior Chamber ? fluid
there doesnt drain correctly which puts pressure
on the back of the eye especially the optic nerve