Lecture 23

Question 1

where are photoreceptors

Answer 1

outer most layer of the retina

Question 2

hy is retina organized in the way it is

Answer 2

nutrient availability

Question 3

what cells send info away to the brain

Answer 3

ganglion cells

Question 4

what layer has synapses happening

Answer 4

plexiform layer

Question 5

rods

Answer 5

cylindrical
90 million
periphery of retina
night vision

Question 6

cones

Answer 6

conical
4-5 million
mostly in fovea
day vision
high acuity
colour vision

Question 7

cone density is highest

Answer 7

in the fovea

Question 8

rod density is highest

Answer 8

in the periphery

Question 9

where is the blind spot and why don’t we see a blindspot

Answer 9

the optic disk, brain fills it in

Question 10

rule of thumb

Answer 10

arms length away, thumb takes up 2 degrees of retina

Question 11

scotopic

Answer 11

rods activated at low light levels because rods are more efficient than cones at converting photon absorption to neural signals
darker than starlight

Question 12

mesopic

Answer 12

cones and rods activated

starlight to between moonlight and indoor lighting

Question 13

photopic

Answer 13

only cones activated at high light levels as they can prevent bleaching at high light intensities
between moonlight and indoor lighting and brighter

Question 14

where is photopigment made

Answer 14

inner segments of photoreceptors

Question 15

where is photopigment stored

Answer 15

outer segments of photoreceptors

Question 16

each photopigment contains ________+_________

Answer 16

protein + chromophore

Question 17

protein in photopigment

Answer 17

opsin

determines what wavelengths are absorbed

Question 18

chromophore in photopigment

Answer 18

retinal

determines colour selectivity

Question 19

what is spectophotometry

Answer 19

measure of how much of the incoming light is absorbed by a protein

Question 20

what is human peak sensitivity to light in dim conditions

Answer 20

500 nm

Question 21

how many types of cones is there, what is difference

Answer 21

3, opsin part

Question 22

dark adaptation experiment is run by

Answer 22

measuring detection threshold of light at various intervals after bleaching

Question 23

how long does it take cones to recover from bleaching

Answer 23

5 minutes

Question 24

how long does it take rods to recover from bleaching

Answer 24

20-25 minutes

Question 25

which photoreceptor needs more light to activate

Answer 25

cones

Question 26

midget bipolar cell

Answer 26

small bipolar cell in the central retina that receives input from a single cone