L4 Retinal Processing

Question 1

What is the main purpose of the sclera?

Answer 1

light reflection

Question 2

What is the main purpose of the retina?

Answer 2

It is where light perception takes place

Question 3

What is accommodation?

Answer 3

It is changes in the lense shape to refract light @ the correct angle in distance and near vision

Question 4

Where is the focal point in emmetropia (normal vision)?

Answer 4

at the retina

Question 5

Where is the focal point in myopia (near sighted)?

Answer 5

ahead of the retina

Question 6

Where is the focal point in hyperopia (farsighted)?

Answer 6

behind the retina

Question 7

Where is the region of high visual acuity?

Answer 7

fovea

Question 8

Where is the fovea located?

Answer 8

w/in the macula lutea

Question 9

What is the blind spot of the eye?

Answer 9

the optical disk or papilla

Question 10

Why don’t we notice the blind spot in our eyes?

Answer 10

Our eyes are always moving the make up for the blind spot

Question 11

What is the visual field ?

Answer 11

what you are actually looking at in space

Question 12

What is the retinal field?

Answer 12

How visual field is projected on to the retina

Question 13

What is the relationship b/n the retinal and visual field?

Answer 13

the retinal field is the visual field upside down and backwards

Question 14

Why does the inf. field require more peripheral monocular vision?

Answer 14

b/c our vision is partially blocked by our nose

Question 15

Where does optical cross over occur?

Answer 15

at the optic chiasm

Question 16

What are the 2 types of photorecptors?

Answer 16

rods and cones

Question 17

What would cause complete vision loss?

Answer 17

damage to the optic nerve

Question 18

Where are the photoreceptive components located?

Answer 18

in the the epithelial cells

Question 19

T/F photoreceptive aspects of rods and cones don’t need to be recycled

Answer 19

False, they do need to be recycled

Question 20

What is the chem. in rods that abs. light?

Answer 20

Rhodopsin

Question 21

What are the two diff. b/n rods and cones?

Answer 21

1. Which chem is present
2. what wavelength of light they respond to

Question 22

When are photoreceptors depolarized?

Answer 22

in the dark

Question 23

What happens when photoreceptors are depol?

Answer 23

Glutamate is released
Na+ chnls are open

Question 24

What causes photoreceptors to hyperpol?

Answer 24

Light

Question 25

What happens when photoreceptors are exposed to light?

Answer 25

No glutamate prod. Na+ chnls close

Question 26

what % of vitamin A is stored in the liver?

Answer 26

50-85%

Question 27

T/F Vit A is essential for signaling an recycling

Answer 27

true

Question 28

What is the major structural diff b/n rods and cones?

Answer 28

Rods have a larger photoreceptive area

Question 29

What type of ganglion are NMDA receptors assoc w?

Answer 29

Off-center

Question 30

What type of ganglion are mGLU receptors assoc w?

Answer 30

On center

Question 31

What are functional ganglion responses due to?

Answer 31

bipolar cell responses via glutamate

Question 32

T/F glutamate is only inhibitory

Answer 32

false, it is inhibitory and excitatory

Question 33

What variables determine receptive fields of retina?

Answer 33

duration of spot illlumin. size of spot illumin. background light intensity

Question 34

Where are cones located?

Answer 34

macula zone

Question 35

Comparing rods and cones, which is more abundant overall?

Answer 35

Rods

Question 36

What do rods sense?

Answer 36

light

Question 37

What do cones sense?

Answer 37

color and detail

Question 38

what are luminance units?

Answer 38

candela (cd) / unit area (m^2)

Question 39

What is most active during scotopic function?

Answer 39

only rods

Question 40

What is most active during mesopic function?

Answer 40

rods and cones are equally active

Question 41

What is most active during photopic function?

Answer 41

only cones

Question 42

What is protanopia?

Answer 42

loss of red opsins

Question 43

What is deuteranopia?

Answer 43

loss of green opsins

Question 44

What is trichromat?

Answer 44

having all three opsins

Question 45

What types of synapses are in the retina?

Answer 45

chemical and electrical

Question 46

Amacrine cells have lateral receptors. Why?

Answer 46

for identification of motion and shape

Question 47

What cells release GABA in lateral information flow?

Answer 47

horizontal cells

Question 48

What is the point of lateral inhibition?

Answer 48

promotes contrast enhancement and edge detection

Question 49

What type of signaling does lat. inhibition rely one?

Answer 49

Gap junctions

Question 50

What is retinal prosthesis?

Answer 50

inserting a computer chip directly in the retina to relay to the nerve

Question 51

What is the difference b/n retinal and cortical prosthesis?

Answer 51

retinal is in the retina cortical is from the visual cotex

Question 52

What encodes the visual scene?

Answer 52

retinal ganglion cells which are processed in the visual cortex