Physiology of Vision

Question 1

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Answer 1

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Question 2

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Answer 2

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Question 3

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Answer 3

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Question 4

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Answer 4

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Question 5

how can the eye make distinctions between slightly different levels of light?

Answer 5

potential for huge differences in amount of sodium influx

Question 6

rods used in what light level?

Answer 6

low light

Question 7

cone cell function?

Answer 7

colour vision

not stimulated in low light, hence things are grey in the dark

Question 8

convergence?

Answer 8

number of photoreceptors converging on a single ganglion
more photoreceptors on a single ganglion = high convergence = increases sensitivity but low acuity (e.g rod cells - hence poor vision in the dark)
opposite also true

Question 9

3 types of cone cell?

Answer 9

short wave (blue)
middle wave (green)
long wave (red)

Question 10

processing of vision begins where?

Answer 10

in the retina via amacrine and horizontal cells?

Question 11

describe the off pathway?

Answer 11

responsive to the dark condition
in the light:
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in the dark:
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contains inotropic glutamate

Question 12

describe the on pathway?

Answer 12

responsive to the light condition
in the light:
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in the dark:
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contains metabotropic glutamate

Question 13

function of amacrine and horizontal cells in the retina?

Answer 13

lateral inhibition
horizontal = receive from photoreceptors and project to other photoreceptors and horizontal cells
amacrine cells = receive from bipolar cells and project to ganglion cells, bipolar cells and other amacrine cells
allows visual fields to be discriminated between photoreceptors

Question 14

what do horizontal cells release?

Answer 14

inhibitory neurones

release GABA on photoreceptors

Question 15

center-surround organization?

Answer 15

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Question 16

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Answer 16

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Question 17

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Answer 17

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