Vision and Eye movements Flashcards

1
Q

what is the coloured part of the eye?

A

the lens

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2
Q

what eye structure receives light from the lens?

A

the retina

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3
Q

what is analogous to the skin?

A

the retina

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4
Q

where are photoreceptors within the eye located?

A

in the peripheral retina

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5
Q

what are photoreceptors analogous to?

A

mechanoreceptors in the skin

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6
Q

what do photoreceptors respond to?

A

a change in light

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7
Q

what are the types of photoreceptors?

A

rods and cones

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8
Q

where are rods primarily found?

A

the peripheral part of the retina

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9
Q

what does it mean that rods are achromatic?

A

the don’t sense colour

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10
Q

what helps us to see in low levels of light?

A

rods

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11
Q

are there more rods or cones?

A

rods! 20:1 ratio

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12
Q

where are cones found in the retina?

A

centre of the retina (fovea)

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13
Q

what lets us see colour?

A

cones

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14
Q

what is the region of the retina where axons are leaving?

A

optic disk

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15
Q

where in the eye are there no photoreceptors?

A

in the optic disk (blind spot)

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16
Q

is the blind spot the same in both eyes?

A

no

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17
Q

where does most of our vision come from?

A

macula

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18
Q

what eye structure is responsible for detailed vision?

A

fovea

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19
Q

where does all the high acuity vision occur?

A

in the center of the retina

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20
Q

what are the 2 types of ganglia in the ganglion cell layer of the eye?

A

parasol ganglion cells

midget ganglion cells

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21
Q

what are characteristics of parasol ganglion cells?

A

large cell bodies, receptive fields, axons

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22
Q

what are the characteristics of the midget ganglion cells?

A

small cell bodies, receptive fields, axons

fine visual detail and colour

more numerous

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23
Q

what demographic often has macular degeneration?

A

people with diabetes
older individuals

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24
Q

what eye structure is impacted with macular degeneration?

A

macula

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25
Q

what does macular degeneration look like?

A

central vision affected

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26
Q

what causes diabetic retinopathy?

A

excess blood sugar damages retinal blood vessels

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27
Q

what does diabetic retinopathy look like?

A

patty vision loss throughout the visual field

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28
Q

what is cataracts?

A

blurring of the lens or a clear coating over the eye

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29
Q

what causes glaucoma?

A

increased intraocular pressure

30
Q

what eye structure is damaged in glaucoma?

A

the optic nerve so often peripheral deficits (looks like a spot light)

31
Q

once information leaves the eye where does it end up in the brain?

A

primary visual cortex

32
Q

as visual information comes into the eye, what happens to it?

A

it gets reversed and flipped upside down

33
Q

where do 60% of fibres cross?

A

optic chiasm

34
Q

what does the optic nerve turn into after the optic chiasm?

A

optic tract

35
Q

does the left optic tract contain fibres from the left or right eye?

A

both! optic tracts have information from both eyes

36
Q

where is the visual system going through the thalamus?

A

lateral geniculate bodies

37
Q

what are the magnocellular layers of the thalamus responsible for?

A

motion and spatial analysis

(information received from the parasol ganglion cells)

38
Q

what are the parvocellular layers responsible for?

A

detailed form and colour

(information from the midget ganglion cells)

39
Q

what is the conscious visual system?

A

retina-geniculate pathway

40
Q

why are the extrageniculate pathways named that?

A

because they do not go to the thalamus

41
Q

what are the subconscious visual systems?

A

extrageniculate pathway

42
Q

what is the purpose of the pretectum subcortical region?

A

controls the pupillary light reflex

43
Q

what is the function of the superior colliculus subcortical region?

A

controls orienting eye movements?

44
Q

what is the function of the hypothalamus subcortical region?

A

regulates circadian rhythms

45
Q

what artery supplies the occipital lobe?

A

posterior cerebral artery

46
Q

where is the primary visual cortex located?

A

in the occipital lobe

47
Q

what does the where pathway do?

A

analyses where something is in space

48
Q

where does the where pathway go?

A

up to the parietal lobe

49
Q

where does the what pathway go?

A

to the temporal lobe

50
Q

what happens at the what pathway?

A

information about form and colour is processed

51
Q

a lesion in what area of the brain can result in an inability to recognize faces?

A

right inferior temporal lobe

52
Q

what is the medical term for the inability to recognize faces?

A

prosopagnosia

53
Q

what muscles move the eyes laterally or medially?

A

lateral and medial rectus

54
Q

what muscles move our eyes up and down?

A

superior and inferior rectus

55
Q

what muscles turn our eyes in the socket?

A

inferior oblique (extorsion: turn our eyes out)

superior oblique (intorsion: turns the eyes in)

56
Q

what is the key difference between skeletal muscles and eye muscles?

A

skeletal muscles are controlled by spinal nerves, eye muscles are controlled by cranial nerves

57
Q

what are the brainstem gaze centres?

A

responsible for the automatic control of our extra ocular muscles

58
Q

what do the brainstem gaze centers do?

A

direct the movement of the eyes (they coordinate the left and right eyes to move together)

59
Q

what does conjugate gaze mean?

A

both eyes move at the same time in the same direction

60
Q

what is the actual name of the horizontal gaze center?

A

PPRF

61
Q

what is the main function of the MLF?

A

it is yoking the two eyes together

62
Q

what does it mean that saccadic eye movements are ballistic?

A

once you start a saccade in a direction, you don’t stop until you’ve rested on the object of interest

63
Q

what are the purpose of saccadic eye movements?

A

to bring targets of interest into our central vision

64
Q

what are saccades directed by?

A

our gaze enters

65
Q

what controls our saccades?

A

superior colliculus
frontal eye fields

66
Q

what communicates with the PPRF to set off the horizontal eye gaze?

A

superior colliculus and frontal visual fields

67
Q

how do we track an object that’s moving?

A

smooth pursuits

68
Q

can we do a smooth pursuit without a moving stimulus?

A

no

69
Q

smooth pursuits occur via which pathway?

A

the ‘where’ pathway

70
Q

what is optokinetic nystagmus a combination of?

A

saccade and smooth pursuit

71
Q

what is another term for optokinetic nystagmus?

A

“train nystagmus”