Transduction

Question 1

Retina cells

Answer 1

Photoreceptors: Rods and Cones
■ One form of energy into another
■ EMF (light) to action potential

Question 2

Bipolar cells

Answer 2

receive input from photoreceptors

Question 3

Ganglion cells

Answer 3

Receive input from bipolar cells (output to brain)

Question 4

Amacrine cells

Answer 4

Connect with bipolar and ganglion cells
● Local neuron; inhibition

Question 5

Horizontal cells

Answer 5

■ Interconnect with photoreceptors
● Local neuron; inhibition

Question 6

Macula

Answer 6

○ 3mm X 5mm center of retina
■ Fovea, center of the macula
● All cones
● Each receptor has direct pathway to the brain
● One bipolar cell and one ganglion cell
■ Optic disk is blind spot

Question 7

Rods (scotopic vision): in the periphery

Answer 7

■ 120 million in each eye
■ Low light
■ Grayscale

Question 8

Cones (photopic vision): mostly in and around fovea

Answer 8

■ 6 million
■ Bright light
■ Color vision

Question 9

Periphery provides better sensitivity to dim light

Answer 9

■ Multiple receptors converge onto bipolar and ganglion cells
■ Poor acuity but good detection
■ Rangers make way in dark by using peripheral vision

Question 10

Young Helmholtz theory, Trichromatic theory

Answer 10

■ Cones respond to light via pigments [iodopsins]
● Long (“red”)
● Medium (“green”)
● Short (“blue”)

Question 11

Rods [rhodopsin]

Answer 11

● No color
● Not in fovea

Question 12

Opponent process theory

Answer 12

■ Opponent cells in ganglion layer
■ Turned “on” by one color and “off” by another
■ Opponent pairs:
● Red-green
● Blue-yellow
● black-white