lecture 1 intro/lect 2 duplex retina

Question 1

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

Answer 1

rods and cones in the outer plexiform layer

Question 2

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

Answer 2

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

Question 3

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

Answer 3

light

Question 4

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

Answer 4

recoverin

Question 5

Glutamate in the retina is…

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

Answer 5

c) both

Question 6

The “duplex retina” refers to what?

Answer 6

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

Question 7

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

Answer 7

False-its the opposite

Question 8

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

Answer 8

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

Question 9

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

Answer 9

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

Question 10

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

Answer 10

true

Question 11

scotopic vision includes:

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

Answer 11

b) scotopic=rods

photopic=cones
mesopic=both rods and cones

Question 12

moonlit paper is an example of:

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

Answer 12

b)mesopic

Question 13

starlit paper is an example of:

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

Answer 13

c) scotopic

Question 14

sunlit paper is an example of:

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

Answer 14

a) photopic

Question 15

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

Answer 15

outer,

Question 16

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

Answer 16

discs in rods=free floating

discs in cones=bound by a membrane

Question 17

humans are trichromatic because we have 3 types of ____.

Answer 17

cones–s,m,and l

Question 18

S cones peak and color:

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

Answer 18

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.

Question 19

true or false: you can detect 1 photon

Answer 19

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.

Question 20

percentage of total retinal cones found in the fovea

Answer 20

5%

Question 21

percentage of total retinal rods found in fovea

Answer 21

0%, only cones in fovea

Question 22

Are there more cones or more rods in the retina?

Answer 22

more rods overall

Question 23

what type of photoreceptors are found in the optic disc?

Answer 23

none, its a blind spot

Question 24

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

Answer 24

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.

Question 25

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

Answer 25

optimal acuity

Question 26

rod wavelength sensitivity peaks at ____nm

Answer 26

505nm (495-507...some variance)

Question 27

it takes ___ to ___ minutes to dark adapt

Answer 27

25-30

Question 28

most vision happens within ___ to ___ degrees of the fovea

Answer 28

20-30

Question 29

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

Answer 29

fovea

Question 30

which 2 cones are predominately found in the fovea?

Answer 30

M and L

Question 31

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?

Answer 31

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

Question 32

what is a photochromatic interval?

Answer 32

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

Question 33

name the 5 factors that determine the time when dark adapting

Answer 33

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

Question 34

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

Answer 34

a troland (cd/m2)

Question 35

rod monochromats should wear ____ tinted glasses

Answer 35

red

Question 36

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

Answer 36

violet

Question 37

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

Answer 37

false-rhodopsin regeneration time is slower