lecture 1 intro/lect 2 duplex retina Flashcards
Horizontal cells stretch horizontally and synapse with which type of retinal cell? and in which retinal layer
rods and cones in the outer plexiform layer
Amacrine cells stretch horizontally and synapse with which type(s) of retinal cell? and in which retinal layer
presynaptic connections with bipolar and post-synaptic with bipolar and ganglion cells in the inner plexiform layer
What causes retinol-11-cis to convert to retinal-11-trans?
light
What causes retinol-11-trans to convert to retinal-11-cis?
recoverin
Glutamate in the retina is…
a) excitatory
b) inhibitory
c) both excitatory and inhibitory
d) neither, Glutamate is not a neurotransmitter
c) both
The “duplex retina” refers to what?
dual functioning of light and dark/rod and cone property of the retina.
True or False: Rods are sensitive to bright light and cones are sensitive to dim light
False-its the opposite
true or false: rods are more sensitive to light than cones
true-rods get overstimulated in light and have a large surface area with more discs than cones.
What is the rod/cone threshold in (cd/m2)?
0.03cd/m2–rods detect light below this value, cones detect light above this value
true or false: rods do not function in bright light because they are overstimulated and cones do not function at all in the dark.
true
scotopic vision includes:
a) cone function
b) rod function
c) both cone and rod function
b) scotopic=rods
photopic=cones
mesopic=both rods and cones
moonlit paper is an example of:
a) photopic vision
b) mesopic vision
c) scotopic vision
b)mesopic
starlit paper is an example of:
a) photopic vision
b) mesopic vision
c) scotopic vision
c) scotopic
sunlit paper is an example of:
a) photopic vision
b) mesopic vision
c) scotopic vision
a) photopic
opsins are found in _____ segments of rods and cones, this is also where light is absorbed.
outer,
Of the discs found in cones and rods, which are free floating and which are bound by a membrane?
discs in rods=free floating
discs in cones=bound by a membrane
humans are trichromatic because we have 3 types of ____.
cones–s,m,and l
S cones peak and color:
a) 534nm and green
b) 420nm and blue
c) 564nm and red
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.
true or false: you can detect 1 photon
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.
percentage of total retinal cones found in the fovea
5%
percentage of total retinal rods found in fovea
0%, only cones in fovea
Are there more cones or more rods in the retina?
more rods overall
what type of photoreceptors are found in the optic disc?
none, its a blind spot
true or false: differences in cone density ratios account for differences in color vision.
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.
normal lit paper has a luminance of 1000 cd/m2 and is _____ _____ for rod saturation
optimal acuity
rod wavelength sensitivity peaks at ____nm
505nm (495-507…some variance)
it takes ___ to ___ minutes to dark adapt
25-30
most vision happens within ___ to ___ degrees of the fovea
20-30
where in the retina will you find the highest density of any photoreceptors?
fovea
which 2 cones are predominately found in the fovea?
M and L
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 tetrad arrangment of 4 cone types, red, blue, green, and UV.
what is a photochromatic interval?
the difference between rod and cone plateaus on a dark adaption graph of “log threshold” vs “time
name the 5 factors that determine the time when dark adapting
1) light intensity 2) light duration 3) wavelength 4) location of light on the retina 5) rhodopsin regeneration
a measurement of how much light gets into a certain diameter pupil is called:
a troland (cd/m2)
rod monochromats should wear ____ tinted glasses
red
what color is has the lowest threshold of sensitivity, making it easier to see?
violet
true or false: rhodopsin has a faster regeneration time than conopsin
false-rhodopsin regeneration time is slower
