The Retina Flashcards Preview

BMS109 Neuroscience > The Retina > Flashcards

Flashcards in The Retina Deck (42)
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1
Q

What does light travel through before it reaches photoreceptors

A

ganglion and bipolar cells

2
Q

What absorbs light that has passed through the retina

A

pigmented epithelium

3
Q

What do ganglion cells receive

A

output from the retina

4
Q

What do amacrine cells influence

A

ganglion cells, bipolar cells, other amacrine cells

5
Q

What do amacrine cells recieve

A

input from bipolar cells

6
Q

What is the function of bipolar cells

A

connect to photoreceptors to ganglion cells

7
Q

What do horizontal cells receive

A

input and output from photoreceptors, output to bipolar cells

8
Q

What are photoreceptors

A

sensory transducers

9
Q

Describe the structure of photorecetors

A

membrane invaginations, membranous disks

10
Q

What do the membranous disks in photoreceptors contain

A

light sensitive photopigments

11
Q

What is the function of photopigments

A

absorb light

12
Q

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

A

FALSE

13
Q

What do rod photoreceptors detect

A

light

14
Q

What is the more numerous photoreceptor

A

rods

15
Q

Describe the characteristics of rod photoreceptors

A

low visual acuity/resolution

16
Q

What is the function fo rod photoreceptors

A

enable vision in low light

17
Q

What is the photopigment associated with rods

A

rhodopsin

18
Q

What are cone photoreceptors used for

A

colour

19
Q

Describe the characteristics of cone photoreceptors

A

high visual acuity/resolution, lower sensitivity

20
Q

Where is the concentration of cone photoreceptors highest

A

fovea

21
Q

What are the cone photopigments

A

three varieties of opsin - S, M, L

22
Q

Describe the characteristics of the fovea

A

low convergence, low sensitivity, high resolution

23
Q

Describe the connection of cones in the fovea

A

each cone connected to ONE ganglion

24
Q

Describe the characteristics of the peripheral retina

A

high convergence, high sensitivity, low resolution

25
Q

What is the connection to ganglion cells in the peripheral retina

A

lots of rods to one ganglion

26
Q

Describe the receptive field of ganglion cells in peripheral retina

A

large receptive field

27
Q

What is the retinal ganglion photopigment

A

melanopsin

28
Q

What is the effect of light on photoreceptors

A

hyper-polarisation

29
Q

What is the resting potential of photoreceptors

A

-35mV

30
Q

What channels are open in the dark

A

cGMP gated non selective cation channels

31
Q

Describe the movement of ions in photoreceptors in the dark

A

Na+ moves in - depolarisation

32
Q

How does light affect cGMP levels

A

increased light decreases cGMP levels

33
Q

Describe the movement of ions into photoreceptors in presence of light

A

X Na+ influx - hyper polarisation

34
Q

What activates rhodopsin

A

light

35
Q

What does active rhodopsin stimulate

A

G protein transducin into transducin GTP

36
Q

What enzyme reduces cGMP levels

A

enzyme phosphodiesterase

37
Q

What does light adaptation of photoreceptors require

A

calcium

38
Q

What does calcium block in the dark

A

guanylyl cyclase

39
Q

Describe the effect of NO calcium on cells

A

more cGMP is produced - channels open

40
Q

What is the function of retinal ganglion cells

A

detect ambient light levels

41
Q

What do retinal ganglion cells respond to

A

photons

42
Q

What are retinal ganglion cells important for

A

circadian rhythm