which part of the eye is in control of light and how does it do it?
the iris by the contraction and relaxation of circular and radial muscles
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what is the definition of accomadation and which two components cause refraction?
the ability to focus light from objects at different distances into the retina. The cornea and lens
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what are the name of the light receptor cells and were are these found?
Rods, spread evenly across the whole retina. Cones concentrated to the fovea but a few scattered in the retina.
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How are rod cells adopted for dark adoption?
contain rhodopsin. in light it remains broken down as opsin and retinal. in darkness it takes 30 minutes for it to be resynthiezed to rhodopsin. Person can now see effectively.
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How do rods have good visual sensitivity?
Convergence of rods allows for summation of low light
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How do cones have good visual acuity?
Each part of the image falls on a differetn cones ceel, so a single impulse is sent along a seperate neurone to the brain
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what is iodopsin and how many forms is there?
its found in cone cells. 3 different forms each sentive to either red, blue or green. possible to see diferetn colours by stimulating a combination of cone cells.
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why do rods have poor visual acuity?
due to the large number of rods synapsed to one bipolar cell. images falling in rods can no be seen as seperate by the brain. all impulses arrive at the brain as one single impulse
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why do cone have poor visual sensitivity?
in a dim light there is insufficent stimulus from a cone to generate an impulse
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Other cards in this set
Card 2
Front
what is the definition of accomadation and which two components cause refraction?
Back
the ability to focus light from objects at different distances into the retina. The cornea and lens
Card 3
Front
what are the name of the light receptor cells and were are these found?
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