lecture 1 intro/lect 2 duplex retina Flashcards

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1
Q

Horizontal cells stretch horizontally and synapse with which type of retinal cell? and in which retinal layer

A

rods and cones in the outer plexiform layer

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2
Q

Amacrine cells stretch horizontally and synapse with which type(s) of retinal cell? and in which retinal layer

A

presynaptic connections with bipolar and post-synaptic with bipolar and ganglion cells in the inner plexiform layer

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3
Q

What causes retinol-11-cis to convert to retinal-11-trans?

A

light

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4
Q

What causes retinol-11-trans to convert to retinal-11-cis?

A

recoverin

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5
Q

Glutamate in the retina is…

a) excitatory
b) inhibitory
c) both excitatory and inhibitory
d) neither, Glutamate is not a neurotransmitter

A

c) both

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6
Q

The “duplex retina” refers to what?

A

dual functioning of light and dark/rod and cone property of the retina.

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7
Q

True or False: Rods are sensitive to bright light and cones are sensitive to dim light

A

False-its the opposite

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8
Q

true or false: rods are more sensitive to light than cones

A

true-rods get overstimulated in light and have a large surface area with more discs than cones.

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9
Q

What is the rod/cone threshold in (cd/m2)?

A

0.03cd/m2–rods detect light below this value, cones detect light above this value

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10
Q

true or false: rods do not function in bright light because they are overstimulated and cones do not function at all in the dark.

A

true

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11
Q

scotopic vision includes:

a) cone function
b) rod function
c) both cone and rod function

A

b) scotopic=rods

photopic=cones
mesopic=both rods and cones

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12
Q

moonlit paper is an example of:

a) photopic vision
b) mesopic vision
c) scotopic vision

A

b)mesopic

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13
Q

starlit paper is an example of:

a) photopic vision
b) mesopic vision
c) scotopic vision

A

c) scotopic

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14
Q

sunlit paper is an example of:

a) photopic vision
b) mesopic vision
c) scotopic vision

A

a) photopic

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15
Q

opsins are found in _____ segments of rods and cones, this is also where light is absorbed.

A

outer,

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16
Q

Of the discs found in cones and rods, which are free floating and which are bound by a membrane?

A

discs in rods=free floating

discs in cones=bound by a membrane

17
Q

humans are trichromatic because we have 3 types of ____.

A

cones–s,m,and l

18
Q

S cones peak and color:

a) 534nm and green
b) 420nm and blue
c) 564nm and red

A

b) 420nm and blue

S=420=”blue”=peak color is also blue
M=534=”green”=peak color is blue-green
L=564=”red”=peak color is yellow-green, however, it is the only cone that stretches absorbency into the red range.

19
Q

true or false: you can detect 1 photon

A

False, you need 100’s to 1000’s of photons to get above threshold (5-14 photons per rod and many many rods). however 1 photon can stimulate electrical activity at the picoamp level, but not enough to relay an image.

20
Q

percentage of total retinal cones found in the fovea

A

5%

21
Q

percentage of total retinal rods found in fovea

A

0%, only cones in fovea

22
Q

Are there more cones or more rods in the retina?

A

more rods overall

23
Q

what type of photoreceptors are found in the optic disc?

A

none, its a blind spot

24
Q

true or false: differences in cone density ratios account for differences in color vision.

A

false- color vision among different people are not due to differences in cone density. cone densities can be 1:1 or even 16:1 and vision is the same.

25
Q

normal lit paper has a luminance of 1000 cd/m2 and is _____ _____ for rod saturation

A

optimal acuity

26
Q

rod wavelength sensitivity peaks at ____nm

A

505nm (495-507…some variance)

27
Q

it takes ___ to ___ minutes to dark adapt

A

25-30

28
Q

most vision happens within ___ to ___ degrees of the fovea

A

20-30

29
Q

where in the retina will you find the highest density of any photoreceptors?

A

fovea

30
Q

which 2 cones are predominately found in the fovea?

A

M and L

31
Q

Most non-primate animals do not have a macula or fovea or any area containing a high concentration of cones. what works in place of this?

A

a tetrad arrangment of 4 cone types, red, blue, green, and UV.

32
Q

what is a photochromatic interval?

A

the difference between rod and cone plateaus on a dark adaption graph of “log threshold” vs “time

33
Q

name the 5 factors that determine the time when dark adapting

A

1) light intensity 2) light duration 3) wavelength 4) location of light on the retina 5) rhodopsin regeneration

34
Q

a measurement of how much light gets into a certain diameter pupil is called:

A

a troland (cd/m2)

35
Q

rod monochromats should wear ____ tinted glasses

A

red

36
Q

what color is has the lowest threshold of sensitivity, making it easier to see?

A

violet

37
Q

true or false: rhodopsin has a faster regeneration time than conopsin

A

false-rhodopsin regeneration time is slower