5 - Vision Flashcards

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1
Q

What does wavelength show

A

colour

short wavelength: violet, blue

longer wavelength: red, orange

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2
Q

What does amplitude show

A

brightness

high amplitude: very bright
low amplitude: dim

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3
Q

What does purity show

A

saturation

high purity/completely saturated: vibrant colours
low purity/desaturated: dull colours

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4
Q

Describe the visual pathway of the eye ball

A
  1. cornea
  2. pupil
  3. lens
  4. vitreous humor
  5. retina
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5
Q

What does the iris do

A

controls the amount of light that enters the eye

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6
Q

What does the pupil do

A

allows light through

low light: large pupil (dilate)
lots of light: small pupil (constrict)

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7
Q

What does the cornea do

A

focuses light

transparent, curved outermost region

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8
Q

What does the lens do

A

final “fine-tuning” focusing

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9
Q

What does the sclera do

A

white region covered by a tough membrane

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10
Q

What is the vitreous humor

A

clear jelly like substnace in main chamber of the eye

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11
Q

What is the retina

A

neural tissue

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12
Q

What is accomodatino

A

when the lens changes shape

close focus: rounder lens
far focus: elongated lens

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13
Q

Describe the cells/layers that light goes through in the retina

A
  1. ganglia cells
    - relays signal to the brain
  2. bipolar cells and amacrine cells
    - processes signal further and passes on to
  3. photoreceptor layer
    - detext light and pass info to the next layer
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14
Q

Describe the photoreceptor cells

A

rods
- low light vision (b/c contains rhodopsin)
- 125 million
- night vision
- poor visual acuity
- concentrated in periphery
- no colour

cones
- high light vision (b/c contains iodopsin)
- 6 million
- day vision
- good visual acuity
- concentrated in fovea
- colour
- smaller receptive fields

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15
Q

What is the retinal pigment epithelium

A

rpe
provides nutrients to photoreceptors

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16
Q

what are horizantal and amacrine cells

A

allow cells in the retina to communicate to each other

some amount of visual processing done in retina before signal sent to the brain

17
Q

What is the blind spot

A

optic disc

area where optic nerves exit the retina

no photoreceptors there

brain makes up what we’re missing

18
Q

where is there a smaller and more precise receptive filed

A

center of retina (fovea)

19
Q

Where is there a larger and coarser receptive field

A

in the periphery of retina

20
Q

What are the streams of the primary visual cortex (V1)

A

ventral stream: “what” pathway
- colour and form
- temporal lobe

dorsal stream: “where” pathway
- depth and motion
- parietal lobe

21
Q

What is topographic organization

A

neighbouring regions in the retina correspond to neighbouring regions in the visual cortex

22
Q

which cells combine into which cells

A

photoreceptors –> ganglion cells –> LGN cells –> visual cortext cells (V1 cells)

23
Q

Describe the evolution of the eye

A
  1. light sensitive patch –> presence or absence of light
  2. curved “cup” eye –> direction of light
  3. pinhole eye –> can resolve detail of image by changing light in the eye
  4. crude lens –> lens and cornea and spherical shape –> relatively solid, shape changes very little
  5. adjustable lens –> flexible and allows for accommodation –> can focus at varying distances
24
Q

What is cumulative selection

A

an evolutionary process whereby new adaptations are layered upon old adaptations

25
Q

What are the factors affecting variance across species

A
  • geographic location
  • where their food comes from
  • movement, shape and colour of prey
26
Q

What are the eye types

A

simple eyes
- eyeball, lens, retina
* crude lens and accommodating lens

compound eyes
- detect movement at close distances
- retina, lens and ommatidium (each point in a slightly different direction to gather the light that lays directly in front of it)

27
Q

What are the functions of the eye
Which eye shape increases the functions

A
  1. resolution: acuity
    - clarity and sharpness
  2. sensitivity: ability to get enough light
    - spotting a far star at night (night vision)

bigger eyes = increase acuity and sensitivity

28
Q

Hoe do human/hawk eyes differ from cat/horse/owl eyes and deep sea animal eyes

A

humans/hawks:
- acuity = excellent
- low-light vision = poor

cat/horse/owl:
- acuity = poor
- low-light vision = excellent

deep sea animals:
- acuity = excellent
- low-light vision = excellent

29
Q

What are laterally directed eyes

A

wide total view
2 separate fields of view
poor depth perception

  • prey animals continually scan environment for predators
30
Q

What are front-facing eyes

A

predators

narrow total view
essentially single field view
excellent depth percetion

31
Q

TF vision is the most developped system in fetuses

A

False
- a lot of additional work that has to be done b/f fully functional

32
Q

What happens at the second prenatal month

A

eyes formed

33
Q

what happens at the 6th prenatal month

A

fetus reacts to light
random firing of retinal cells

34
Q

Describe the eyes of a newborn

A

weak lens muscle (limits how well they can focus)

inconsistent pupil rxn (can’t react properly to changes in light –> blurry images)

low cell density

cells are immature (especially fovea –> matures at 4 years)

35
Q

Describe the eye at 3 months

A

almost adult-like focusing

36
Q

Describe the eye at 11 years

A

visual brain area development complete

37
Q

When is visual acuity fully developed

A

1 year