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17 Cards in this Set
- Front
- Back
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What type of receptors are rhodopsin and cone pigments?
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G-protein coupled
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In the case of _____ and _______, the ligand of the receptor protein opsin rather than being a neurotransmitter or an odorant, is a vitamin A derivative (11-cis retinal) that enables photopigments to absorb visible light.
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rods and cones
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Vitamin A derivative 11-cis retinal is the ligand of the receptor protein opsin ---> opsin in its altered conformation activates nearby molecules of transducin (G-protein) ---> transducin activates ________________ which hydrolyzes cGMP (rapidly)
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phosphodiesterase
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Light induced hydrolysis of cGMP causes cation channels to (open or close?) thus causing the membrane to hyperpolarize toward the potassium equilibrium potential and transmitter release declines.
Rods and cones in the dark are relatively polarized or depolarized? What neurotransmitter do rods and cones release at a steady state onto processes of bipolar and horizontal cells? |
close
depolarized glutamate |
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Answer choices rods and cones.
_____ are less sensitive than ______, and their responses are faster and briefer. |
Cones are less sensitive than rods, and their responses are faster and briefer.
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Answer choices rods and cones.
______ fx in dim light. |
Rods
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Answer choices rods and cones.
Are more sensitive Can only respond in levels of light up to moonlight, and are saturated at room light Responses are slow Spatial resolution in dim light is relatively poor Contain rhodopsin Every photon absorbed sets in motion the same G-protein coupled cascade. |
Rods
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True or False
A dim 500nm stimulus causes the same receptor potential as a brighter 600nm stimulus. |
True pg 432 regarding Rods Fx in Dim Light
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True or False
Populations of Rods signal spatial detail and color |
False
Populations of cones signal spatial detail and color. |
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Answer choices rods and cones.
Less sensitive yet faster Require moonlight or greater to fx |
cones
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Scotopic vision - use only rods
Mesopic vision - use rods & cones Photopic vision - use only cones. |
Moonlight
Starlight Brighter than startlight |
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Answer choices rods and cones.
There is considerably less convergence in ______ pathway. |
cone
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In what part of the spectrum are Red cones (long-wavelength cones) most active?
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Yellow-green range
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What are the three kinds of cones?
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Long wavelength (red) {only 5% of cones)
Middle wavelength (green) Short wavelength (blue) Ratio of L:M in a person with normal vision can vary from 1:1 to 15:1 !!! |
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Even though cones, like rods can report only the number of _______ absorbed and not their wavelength, the relative activity levels of multiple populations of cones provide information about wavelength.
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photons
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The genes for the red and green cone pigments are loacted next to each other on the X chromosome, and unequal crossing over during meiosis can cause one X chromosome to wind up with a missing or defective red or green gene,....causing....
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red-green
color blindness in 2% of the male population. |
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A cell at any given level in the visual system, like a cell in the somatosensory system, can be characterized by its _________ ______, which in this case refers to the retinal area in which changing conditions of illumination produce an alteration of the cell's activity.
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Receptive field
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