The Retina

Question 1

What does light travel through before it reaches photoreceptors

Answer 1

ganglion and bipolar cells

Question 2

What absorbs light that has passed through the retina

Answer 2

pigmented epithelium

Question 3

What do ganglion cells receive

Answer 3

output from the retina

Question 4

What do amacrine cells influence

Answer 4

ganglion cells, bipolar cells, other amacrine cells

Question 5

What do amacrine cells recieve

Answer 5

input from bipolar cells

Question 6

What is the function of bipolar cells

Answer 6

connect to photoreceptors to ganglion cells

Question 7

What do horizontal cells receive

Answer 7

input and output from photoreceptors, output to bipolar cells

Question 8

What are photoreceptors

Answer 8

sensory transducers

Question 9

Describe the structure of photorecetors

Answer 9

membrane invaginations, membranous disks

Question 10

What do the membranous disks in photoreceptors contain

Answer 10

light sensitive photopigments

Question 11

What is the function of photopigments

Answer 11

absorb light

Question 12

TRUE or FALSE - monochrome and colour can be detected by the same system

Answer 12

FALSE

Question 13

What do rod photoreceptors detect

Answer 13

light

Question 14

What is the more numerous photoreceptor

Answer 14

rods

Question 15

Describe the characteristics of rod photoreceptors

Answer 15

low visual acuity/resolution

Question 16

What is the function fo rod photoreceptors

Answer 16

enable vision in low light

Question 17

What is the photopigment associated with rods

Answer 17

rhodopsin

Question 18

What are cone photoreceptors used for

Answer 18

colour

Question 19

Describe the characteristics of cone photoreceptors

Answer 19

high visual acuity/resolution, lower sensitivity

Question 20

Where is the concentration of cone photoreceptors highest

Answer 20

fovea

Question 21

What are the cone photopigments

Answer 21

three varieties of opsin - S, M, L

Question 22

Describe the characteristics of the fovea

Answer 22

low convergence, low sensitivity, high resolution

Question 23

Describe the connection of cones in the fovea

Answer 23

each cone connected to ONE ganglion

Question 24

Describe the characteristics of the peripheral retina

Answer 24

high convergence, high sensitivity, low resolution

Question 25

What is the connection to ganglion cells in the peripheral retina

Answer 25

lots of rods to one ganglion

Question 26

Describe the receptive field of ganglion cells in peripheral retina

Answer 26

large receptive field

Question 27

What is the retinal ganglion photopigment

Answer 27

melanopsin

Question 28

What is the effect of light on photoreceptors

Answer 28

hyper-polarisation

Question 29

What is the resting potential of photoreceptors

Answer 29

-35mV

Question 30

What channels are open in the dark

Answer 30

cGMP gated non selective cation channels

Question 31

Describe the movement of ions in photoreceptors in the dark

Answer 31

Na+ moves in - depolarisation

Question 32

How does light affect cGMP levels

Answer 32

increased light decreases cGMP levels

Question 33

Describe the movement of ions into photoreceptors in presence of light

Answer 33

X Na+ influx - hyper polarisation

Question 34

What activates rhodopsin

Answer 34

light

Question 35

What does active rhodopsin stimulate

Answer 35

G protein transducin into transducin GTP

Question 36

What enzyme reduces cGMP levels

Answer 36

enzyme phosphodiesterase

Question 37

What does light adaptation of photoreceptors require

Answer 37

calcium

Question 38

What does calcium block in the dark

Answer 38

guanylyl cyclase

Question 39

Describe the effect of NO calcium on cells

Answer 39

more cGMP is produced - channels open

Question 40

What is the function of retinal ganglion cells

Answer 40

detect ambient light levels

Question 41

What do retinal ganglion cells respond to

Answer 41

photons

Question 42

What are retinal ganglion cells important for

Answer 42

circadian rhythm