Retina

Question 1

Two retinal pathways

Answer 1

Vertical and lateral pathways

Question 2

All synapses in the retina (vertical pathway) use this neurotransmitter

Answer 2

glutamate

Question 3

Retinal cell that fires action potentials

Answer 3

Ganglion cells. Rest do graded potentials only

Question 4

Mediate lateral inhibition between photoreceptors

Answer 4

horizontal cells

Question 5

Mediate connections between rod photoreceptors and ganglion cells

Answer 5

amacrine cells

Question 6

Where is the density of cones high in the retina

Answer 6

fovea

Question 7

Where is the density of rods high in the retina

Answer 7

peirphery

Question 8

What does convergence mean in the context of the retina?

Answer 8

Number of photoreceptors per ganglion cell. Greater convergence means more receptors per ganglion cell.

Question 9

Light causes photoreceptor to [depolarize/hyperpolarize]

Answer 9

hyperpolarize

Question 10

Photoreceptors [depolarize/hyperpolarize] in the dark

Answer 10

depolarize

Question 11

Na+ and Ca2+ permeable ligand gated channels on photoreceptors

Answer 11

cGMP gated channels

Question 12

Is cGMP concentration high or low inside photoreceptors in the dark?

Answer 12

High

Question 13

Why does cGMP concentration decrease in photoreceptors exposed to light?

Answer 13

light activates phosphodiesterase, converting cGMP to GMP

Question 14

Two components of photopigment

Answer 14

retinal and opsin

Question 15

Light absorbing chromophore

Answer 15

retinal

Question 16

Retinal binding protein

Answer 16

opsin

Question 17

Retinal’s conformation in absence of light

Answer 17

11-cis-retinal (bent)

Question 18

Retinal’s conformation with light

Answer 18

all-trans-retinal (straight)

Question 19

What stimulates phosphodiesterase after exposed to light?

Answer 19

transducin (g-protein) which is activated by conformation change in opsin

Question 20

Why are rods so sensitive to light

Answer 20

signal amplification

Question 21

What is the difference in cones for different colors?

Answer 21

types of opsin

Question 22

medical term for color blindness

Answer 22

dyschromatopsia

Question 23

What chromosome does loss of blue sight occur on?

Answer 23

chromosome 7

Question 24

What mainly regulates light sensitivity?

Answer 24

Cytoplasmic Ca2+

Question 25

Mechanism for Ca2+ regulating light sensitivity

Answer 25

Modulates affinity of CNG channels for cGMP and activity of guanylyl cyclase

Question 26

Other contributors to light adaptation (besides main Ca2+ mechanism)

Answer 26

1) Other biochemical processes not involving Ca2+ 2) bleaching -- conversion of all retinal to all-trans-retinal 3) pupillary light reflex

Question 27

Mechanism for creation of center-surround receptive fields

Answer 27

Lateral inhibitory connections of horizontal cells create the center-surround receptive fields

Question 28

Photoreceptor-bipolar cell synapses are always inhibitory

Answer 28

false. They can be either excitatory or inhibitory

Question 29

Horizontal cell-photoreceptor synapses are always inhibitory

Answer 29

true

Question 30

Do on-center bipolar cells hyperpolarize or depolarize in response to light?

Answer 30

depolarize

Question 31

Do off-center bipolar cells hyperpolarize or depolarize in response to light?

Answer 31

hyperpolarize

Question 32

Cones have both on-center and off-center bipolar cells. What about rods?

Answer 32

just on-center

Question 33

How rods communicate to the optic nerve?

Answer 33

They borrow cone bipolar cells via their amacrine cells

Question 34

Paraneoplasia

Answer 34

antibody against mGlu6 (glutamate receptor in rod-bipolar cell synapse)

Question 35

Cause of congenital stationary night blindness

Answer 35

several gene mutation affecting on-center bipolar cells (including mGlu6 receptor)

Question 36

Three types of retinal ganglion cells

Answer 36

M-type, P-type, NonM-NonP-type

Question 37

Most common type of retinal ganglion cell

Answer 37

P-type

Question 38

P-type vs M-type retinal ganglion cells: larger receptive field

Answer 38

M-type

Question 39

P-type vs M-type retinal ganglion cells: conduction velocity

Answer 39

P-type not as fast

Question 40

Functional role of M-type retinal ganglion cells

Answer 40

detect movement

Question 41

Functional role of P-type retinal ganglion cells

Answer 41

detect form and fine detail

Question 42

Two types of color-opponent ganglion cells

Answer 42

1) red-green | 2) blue yellow