Vision

Question 1

Light hyperpolarizes highly sensitive photoreceptors in the retina (rods) - T/F

Answer 1

True

Question 2

Light changes the shape of which protein in the rod photoreceptor?

Answer 2

Rhodopsin

Question 3

Why do rods depolarize with light? (clue: what closes?)

Answer 3

Because membrane sodium channels close

Question 4

Where is the blind spot and why is it called that way?

Answer 4

The blind spot where the nerve fibers and blood vessels leave the eyeball, and it is called that way because it does not have any photoreceptors -> cannot see light -> cannot see anything

Question 5

Where is the fovea and what distinguishes it?

Answer 5

The fovea is roughly at the centre of the retina. The fovea is full of cone receptors -> it’s where you see better

Question 6

why is the organization of the retina counterintuitive?

Answer 6

because the photoreceptors are in the very back

Question 7

Why is the retina in the human eye “inverted”? (2 reasons)

Answer 7

Closeness. 1. The Choroid (blood vessels -> energy suplly) is closer to the photoreceptors 2. The RPE (REtinal Pigment Epithelium), reponsible of regenerating new photoreceptors, is also closer to them

Question 8

How many levels of neurons are involved in lateral inhibition?

Answer 8

4 or 3 and a half

Question 9

When I say 3 and a half levels of neurons involved in lateral inhibition, what do I mean with the half?

Answer 9

The half are the INHIBITORY NEURONS. They can be considered half a level because the excitatory neurons send the info they receive from receptors both to them and both directly to ganglion cells

Question 10

What does lateral inhibition do?

Answer 10

It allows us to see the edges of things

Question 11

Which path does the information take once it has reached the receptors? (name the levels)

Answer 11

Receptor -> excitatory bipolar cell -> info goes two ways:

1. directly to ganglion cell (all the info received from receptor, or almost all depending on the efficiency of the cell)
2. to inhibitory cells of the next ganglion cell(all the info received from recepto r, or almost all depending on the efficiency of the cell)
   - > Ganglion cell, which receives three information streams:
3. directly from “its” bipolar cell
4. from the inhibitory cell from the right
5. from the inhibitory cell from the left