Vision Flashcards
1
Q
Retina
A
- Made up of photoreceptors
- Critical
- At the back of the eye
- Without it, we can’t see at all because we can’t convert light to action potentials
2
Q
Fovea
A
- A depression of the retina
- Contains one specific type of photoreceptor (cones)
3
Q
Retinal organization
A
- Ganglion cell layer
- Bipolar cell layer
- Photoreceptor layer
4
Q
How does light pass through the retinal layers?
A
Light bypasses the first two layers (ganglion and bipolar cell layers are not triggered by light), only the photoreceptor layer is stimulated by light
5
Q
Are there more rods or cones in the eye?
A
Rods
6
Q
Where are rods located?
A
Spread out over the retina, sans fovea
7
Q
Where are cones located?
A
Almost entirely in the fovea
8
Q
What light are rods sensitive to?
A
Low levels of brightness
9
Q
What light are cones sensitive to?
A
Bright light
10
Q
What is the specialization of rods?
A
Night vision and motion
11
Q
What is the specialization of cones?
A
Color vision and acuity
12
Q
Transduction in the absence of light
A
- In the dark, photoreceptors are depolarized; they are inhibitory (sending out IPSPs)
- This inhibits/hyperpolarizes the bipolar cell, which is usually excitatory but currently being inhibited
- This prevents action potentials in the ganglion cell
13
Q
Transduction in light
A
- Light hyperpolarizes the photoreceptors via G-protein coupled receptors
- This reduces inhibition of the bipolar cells (which are excitatory); they can now depolarize and fire
- This can now excite the ganglion cells, whose action potentials get sent to the brain
14
Q
Two types of retinal ganglion cells (RGCs)
A
- Magnocellular cells (M cells)
- Parvocellular cells (P cells)
15
Q
Which are larger, M cells or P cells?
A
M cells
