Retina

Question 1

Retina 5 layers

Answer 1

Outer nuclear layer
Outer plexiform layer
Inner nuclear layer
Inner plexiform layer
Ganglion cell layer

Question 2

Where in the eye does light travel to and from?

Answer 2

Travels through the cornea through the retina into the fovea

Question 3

What are discs

Answer 3

Discs occur on photoreceptors and are free floating containing

Question 4

What is disc shedding

Answer 4

Disc shedding is the process by which photoreceptors in the eye are renewed.

Question 5

What is muller cells?

Answer 5

Act as optical fibres in the retina from the front of the retina to the back

Question 6

How bipolar cells link to cones and rods

Answer 6

1 bipolar cell links to 15-30 rods(Convergent)

1 bipolar cell links to 1 cone(One to one)

Question 7

What’s different in the retina synapse compared to a normal synapse

Answer 7

Retina synapses are always on

Question 8

Phototransduction

Answer 8

Phototransduction is the conversion of light into a change in the electrical potential across the cell membrane.

Question 9

What happens to photoreceptors in the dark

Answer 9

Constant release of glutamate

Question 10

What happens when light hits a photoreceptor

Answer 10

Light switches on photoreceptors which decreased the response

Question 11

What is the molecular process of photransduction in the dark

Answer 11

When dark cGMP excites sodium gated channels leading to an increases in calcium and sodium

Question 12

What is the molecular process of photransduction when in light

Answer 12

A G protein is switched on and fewer cGMP is produced closing the cGMP sodium gated channel leading to less sodium and calcium ions and then less glutamate

Question 13

What does calcium and sodium promote in photoreceptors

Answer 13

Depolarisation

Question 14

What does 4th or 5th order process mean

Answer 14

Dependent on a factor such as calcium ions on a synapse

Question 15

Cooperativity

Answer 15

Cooperativity is a phenomenon displayed by systems involving identical or near-identical elements, which act dependently of each other,

Question 16

Why is phototransduction always on

Answer 16

Give a linear response(to give dynamic range) to see a range of visual activity
To give peak intracellular calcium ions and never goes over 500nM

Question 17

Why can’t we use normal synapses in the retina

Answer 17

Too much calcium causing non linearity would be present and cause too much damage(excitotoxic)

Question 18

What is an opsin protein?

Answer 18

Contains retinal and each has a specific light frequency sensitivity

Question 19

What is rhodopsin?

Answer 19

Transduction in rods where light breaks double bond and coverts it from cis to trans activates the break up of cGMP

Question 20

Functional specialisation of rods and cones

Answer 20

Rods have low spatial high sensitivity
Cones have high spatial low sensitivity
These function cover the whole colours

Question 21

Why do we move our heads and eyes so much

Answer 21

Density of cones in the fovea is big so moving our head and eyes maintains our retinal image on the foveal

Question 22

What are the 3 wavelengths are eyes respond to

Answer 22

445nm-blue
508nm-green
565nm- red

Question 23

Rhodopsin

Answer 23

Rhodopsin is the light receptor in rod photoreceptor cells of the retina that initiates scotopic vision.