Module 4.2 - The Visual System Flashcards Preview

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Flashcards in Module 4.2 - The Visual System Deck (60)
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1

light travels in waves that vary in terms of 2 different properties. what are these 2 properties?

length and amplitude

2

true or false: different species see different wavelength

true

3

what are the 3 characteristics of light

wavelength, amplitude, purity

4

in what 3 ways are the characteristics of light experienced by us?

hue, intensity and saturation

5

hue

colour of the spectrum

6

intensity

brightness

7

saturation

colourfullness or density

8

sclera

the white, outer surface of the eye

9

cornea

the clear layer that covers the front portion of the eye and also contributes to the eyes ability to focus

10

pupil

regulates the amount of light that enters by changing its size; it dilates (expands) to allow more light to enter and constricts (shrinks) to allow less light into the eye

11

iris

a round muscle that adjusts the size of the pupil; it also gives the eyes their characteristic colour

12

lens

a clear structure that focuses light onto the back of the eye

13

how does the lens focus light onto the back of the eye?

through the process of accommodation

14

retina

lines the inner surface of the eye and consists of specialized receptors that absorb light and send signals related to the properties of light to the brain

15

true or false: the retina consists of a single layer

FALSE: the retina contains a number of different layers

16

photoreceptors

specialized receptors found at the back of the eye; they send information to biopolar and ganglion cells

17

optic nerve

a dense bundle of fibres that transmit activity from the ganglion cells to the brain

18

optic disc

an area on the retina with no photoreceptors

19

blind spot

area on the retina with no photoreceptors

20

why are we not aware of our blind spot?

because the mind "fills in" the blind spot

21

rods

photoreceptors that occupy peripheral regions of the retina; they are highly sensitive under low light levels

22

what colours are rods most responsive to?

black and grey

23

what is the ratio of rods to ganglion cells?

10:1

24

cones

photoreceptors that are sensitive to the different wavelengths of light that we perceive as colour

25

where are the cones clustered?

around the fovea

26

fovea

the central region of the retina

27

what is the ratio of cones to ganglion cells

1:1

28

dark adaptation

the process by which the rods and cones become increasingly sensitive to light under low levels of illumination

29

trichromatic theory/young Helmholtz theory

colour ion is determined by 3 cone types that are sensitive to short (blue), medium (green) and long (red) wavelengths of light

30

what 3 colours are all other colours derived from?

red green and blue