Ch. 4.1 - The Structure of the Eye

Question 1

sclera

Answer 1

white outer layer of eye

Question 2

cornea

Answer 2

clear layer that covers the front of the eye

Question 3

pupil

Answer 3

regulates amount of light let into eye

Question 4

iris

Answer 4

round muscle that adjusts the size of the pupil

Question 5

lens

Answer 5

clear structure that focuses light onto back of eye

Question 6

cones (2)

Answer 6

• photoreceptors sensitive to wavelengths of light, we perceive as colour; active in normal lighting conditions
• fovea: cone rich region in centre of retina on which light is focused

Question 7

rods

Answer 7

photoreceptors on periphery if retina that are highly sensitive to low light levels

Question 8

dark adaptation

Answer 8

process by which rods and cones gain sensitivity to low light levels

Question 9

bipolar neurons

Answer 9

synapse onto photoreceptors

Question 10

ganglion cells

Answer 10

transmits signals from bipolar neurons to brain

Question 11

optic disc

Answer 11

area on retina lacking rods and cones

Question 12

optic nerve

Answer 12

axon tracts from ganglion cells leading to brain

Question 13

two common vision disorders

Answer 13

nearsightedness and farsightedness

Question 14

trichromatic theory

Answer 14

maintains that colour vision is determined by three different cone types that are sensitive to short, medium, and long wavelength light

Question 15

colour blindness (2)

Answer 15

• dichromatism most common

- dichromatism vs. trichromatism vs. tetrachromatism

Question 16

opponent-process theory (2)

Answer 16

• states that we perceive colour in terms of opposite ends of the spectrum (red to green, yellow to blue, white to black)
• ganglion cells provide three colour ‘channels’

Question 17

evidence from negative afterimages

Answer 17

after prolonged fixation, residual image seem with opposite colours

Question 18

evidence from colourblindness

Answer 18

if only based on trichromatic theory, colour blind individuals should not see yellow

Question 19

retinal neurons

Answer 19

interact to organize visual info

Question 20

horizontal cells (2)

Answer 20

• laterally connection inhibitory interneurons (GABA releasing)
• mach band effect