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38 Cards in this Set
- Front
- Back
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What type of light is scotopic vision sensitive to? |
Little to no light (night time) |
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What photoreceptors are stimulated in scotopic cinditions? |
Rods |
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Describe scotopic conditions in terms of colour |
Cannot discriminate between colours |
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Scotopic vision in terms of visual acuity |
Poor 20/200 |
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How many candelas/m^2 is scotopic vision? |
10^-6 to 10^-3 |
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What type of light is photopic vision sensitive to? |
Bright Day light |
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What photoreceptors are stimulated by photopic vision? |
Cones |
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Photopic vision in terms of colour |
Good colour discrimination |
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Photopic vision in terms of visual acuity |
20/20 |
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Duplex retina |
When 2 photoreceptors operate under different lighting conditions |
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Mesopic vision |
Twilight conditions Both rods and cones |
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How nany rhodopsin molecules per disc |
10,000 |
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1 molecule of rhodopsin can absorb how many photons of light? |
1 rhodopsin molecule can absorb 1 photon of light |
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What happens when rhodopsin absorbs a photon? |
Rod becomes activated and begins to bleach |
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What is the half-life of rhodopsin |
5 minutes |
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What wavelength has the highest probability of absorption? |
507nm |
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What is the law of univariance? |
Once the photon is absorbed, all wavelength information is lost |
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How many rods does it take to activate 1 ganglion cell? |
10 rods to 1 ganglion cell |
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What happens when a ganglion cell is activated? |
The stimulus is detected |
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Why isn't all the light absorbed by rhodopsin? |
Some light becomes reflected |
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What % of light is absorbed by rhodopsin? |
20% |
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How long does it take for dark adaption? |
30-45 mins |
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What is achromatic light? |
Light that is non-colour producing |
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What light condition is achromatic light? |
Photopic (high luminance) |
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Where are cones most dense? |
In the fovea |
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What type of lights do rods absorb? |
Scoptopic (low light) = monochromatic |
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How many rods in retina? |
120 million |
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What does uv light cause? |
Pain |
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What effect does infrared light have on the retina? |
It is warm Does not have an effect on retina |
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What is the purkinje shift? |
When light conditions change from photopic to scotopic |
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As lighting conditions change, what effect does it have on wavelength? |
The wavelengths were most sensitive to changes from 507-555 |
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What is the max wavelength that rhodopsin can absorb? |
507nm |
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Which wavelengths are most sensitive to photopic conditions? |
More sensitive to longer wavelengths |
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Which cones make little contribution to the purkinje shift? |
S cones |
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What is the photochromatic interval? |
The difference in sensitivity between the scotopic and photopic systems at a given wavelength |
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Which wavelength is equally sensitive to rods and cones? |
Red- L cones |
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After which wavelength is photopic most sensitive? |
650nm |
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For what wavelengths is the photochromatic interval close to 0? |
For long wavelengths around the red region of the spectra |
