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Human Neuroscience > Lecture 13: Visual System > Flashcards

Lecture 13: Visual System Flashcards

1
Q

_____: A mechanism for protecting the retina from excessive light

A

Pupillary Light Reflex

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2
Q

In testing for the pupillary light reflex, illumination in one eye produces ___ constriction of pupils. Illuminated eye gives the ___ response and contralateral eye gives ___ response.
A. unilateral; direct; consensual
B. bilateral; direct; consensual

A

B. bilateral; direct; consensual

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3
Q

____ is the central aperture of iris

____ is pigmented disc

_____ is anterior most, avascular and transparent portion of sclera

____ is tough, outermost CT layer

A

Pupil
Iris
Cornea
Sclera

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4
Q

What are the three layers of the eye?

A

Outer: sclera and cornea
Middle: uvea, choroid, cil body, iris
Inner: retina

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5
Q

True or False: Sclera and Cornea are found in outer eye layer while the Retina is found in the inner most layer

A

True

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6
Q

True or False: Cornea and Lens are avascular while Uvea is vascularized

A

True

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7
Q

Which of the following is attached to lens via suspensory ligaments and aids in lens accommodation?
A. Choroid
B. Iris
C. Ciliary Body

A

C. Ciliary Body

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8
Q

____ is suspended from ciliary body by zonular fibers (suspensory ligaments).
A. Corena
B. Sclera
C. Lens
D. Uvea

A

C. Lens

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9
Q

True or False: The zonular fiber that suspend lens from ciliary body helps maintain ellipsoidal shape of lens

A

True

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10
Q

The thickness of the lens is controlled by what?
A. Action of zonular fibers
B. Action of muscle in ciliary body

A

B. Action of muscles in ciliary body

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11
Q

True or False: Iris is an extension of the choroid

A

True

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12
Q
A
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13
Q

What maintains the shape of the eye?

A

Intraocular pressure

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14
Q

_____ is made by body and pushed into anterior and posterior chamber
A. Vitreous humor
B. Aqueous humor

A

B. Aqueous humor

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15
Q

____: a gelatinous mass between lens and retina; slow equilibrium
A. Vitreous humor
B. Aqueous humor

A

A. Vitreous humor

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16
Q

___ work to accommodate (bring objects into focus)

A

Lens

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17
Q

If the ciliary muscles are relaxed and the zonula fibers are under tension, is the lens relaxed or accomodated?

A

Relaxed

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18
Q

If the ciliary muscles are contracted and the zonular fibers are relaxed, is the lens relaxed or accomodated?

A

Accomodated

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19
Q

True or False: When we are looking at a structure in the distance, our lens is flat; if we are looking at an object up close, our lens is fat

A

True

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20
Q

True or False: Iris affects brightness and quality of light entering eye

A

True

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21
Q

____: Pigmented disc with central aperture. It contains smooth muscle fibers that regulate size of pupil and, therefore, among of light that reaches retina.

A

Iris

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22
Q

True or False: The pupillary sphincter is innervated by parasympathetic fibers from ciliary ganglion and constricts pupil; pupillary dilator is innervated by SYMPATHETIC fibers and contracts muscles to enlarge pupil

A

True

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23
Q

True or False: ANS controls pupillary dilation and constriction

A

True

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24
Q

Where does optic nerve exit retina?

A

Via optic disc

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25
Q
A
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26
Q

Which structure improves quality of central vision?
A. Optic Disc
B. Macula
C. Retina

A

B. Macula

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27
Q

True or False: Retina is thicker than fovea

A

False - retina is thinner

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28
Q

True or False: Fovea is associated with greatest acuity, as it has highest concentration of cones

A

True

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29
Q

Why is the optic disc called a blind spot?

A

Lacks photoreceptors

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30
Q

____ is found in the nasal retina while ____ and ___ are found in temporal retina

A

Optic Disc = Nasal Retina
Fovea and Macula Lutea = Temporal

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31
Q

True or False: The outermost layer of the retina contains the rods and cones

A

True

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32
Q

___: Last link in retinal component of visual pathway. Receive impulse from bipolar cells; its axons join to form optic nerve
A. Bipolar Cells
B. Muller Cells
C. Ganglion Cells

A

C. Ganglion Cells

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33
Q

____: Dendrites that receive impulse transmission from rods and cones, and axons of these cell synapse with ganglion cells
A. Bipolar Cells
B. Muller Cells
C. Ganglion Cells

A

A. Bipolar Cells

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34
Q

True or False: Ganglion cell layer is found in innermost retinal layer while photoreceptors are found in outermost retinal layer

A

True

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35
Q

Light path through retina during
visual transduction?

A

True

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36
Q

True or False: While both rods and cones contain light absorbing photopigments, cones contribute to night vision while while rods contribute to day vision

A

False - although both do contain light absorbing photopigments, rods contribute to NIGHT vision while cones work during DAYTIME

37
Q

True or False: Rods are scotopic and more numerous while cones are photopic and less numerous

A

True

38
Q

True or False: Pigments are found in outer segment of rods and cones

A

True

39
Q

___ are specialized for acuity at the expense of sensitivity. Therefore: we do not see color at low illumination

A

Cones

40
Q

Three types of cone pigments?

A

RBG

41
Q

Since rods are sensitive to lower levels of light and response for night vision, at lower levels of illumination, we only see ___ and ___

A

black and white

42
Q

True or False: The fovea is rich in rods

A

False - rich in cones

43
Q

True or False: There are fewer rods and cones in periphery

A

False - there are more

44
Q

True or False: Fovea specializes in high light vision, periphery in low light vision

A

True

45
Q

True or False: Optic nerve is ensheathed in only 2/3 meninges

A

False - in 3/3

46
Q

True or False: Rods are absent from central fovea but increase in periphery of retina

A

True

47
Q

How does one acquire papilledema?

A

Increased intracranial pressure (cerebral edema) causes CSF to compress opthalmic vessel, impede venous drainage, leading to bulge of fluid at optic disc

48
Q

___ projection carries visual info from eyes to internal structures

A

Retinofugal projections

49
Q

When optic nerves join, they create ___ ___

A

optic chiasm

50
Q

True or False: Fibers from temporal visual fields (nasal retinas) cross to opposite side

A

True

51
Q

What is the net result of this partial decussation of the optic nerve/chiasm?

A

Left field of vision projects to right side of brain and vice versa

52
Q

True or False: Both eyes share a visual field

A

False - each have own

53
Q

True or False: Since light travels in straight line, there is complete inverse relationship between visual and retinal field

A

True

54
Q

True or False: Image in visual field is inverted and reversed onto retina

A

True

55
Q

____: center of visual field with image transmitted to fovea of both retinas

A

Fixation point

56
Q
A
57
Q

Vertical division of retina produces ___ and ___ visual fields
A. superior, inferior
B. nasal, temporal
C. right, left

A

B. nasal and temporal

58
Q

Horizontal division of retina produces
___ and ____ visual fields
A. superior, inferior
B. nasal temporal
C. right, left

A

A. superior, inferior

59
Q

Right visual field projects to….
A. Right temporal retina/right nasal retina
B. Right temporal retina/left nasal retina
C. Left temporal retina/right nasal retina

A

C. Left temporal retina/right nasal retina

60
Q

Optic nerve fibers partially decussate in
___ ____

A

optic chiasm

61
Q

Fibers from temporal retina stay ___ while fibers from nasal retina decussate in chiasm

A

Ipsilateral

62
Q

True or False: The entire right visual field
projects to the left side of
the brain

A

True

63
Q

Which condition would you expect to see in one with right monocular field deficit (e.g damage to right optic nerve)?
A. Ipsilateral Blindness
B. Bilateral Hemianopsia
C. Homonymous Hemianopsia

A

A. Ipsilateral Blindness

64
Q

Damage to the optic chiasm/pituitary can lead to which condition?
A. Ipsilateral Blindness
B. Bilateral Hemianopsia
C. Homonymous Hemianopsia

A

B. Bilateral Hemianopsia (loss of lateral visual fields)

65
Q

Damage to optic tract can lead to which condition?
A. Ipsilateral Blindness
B. Bilateral Hemianopsia
C. Homonymous Hemianopsia

A

C. Homonymous Hemianopsia (left temporal visual field and left nasal visual field)

66
Q

Axons of LGN leave LGN to form ____ tract

A

Geniculocalcarine

67
Q

What is the relay station for visual info?

A

Lateral geniculate nucleus of dorsal thalamus

68
Q

True or False: Striate cortex is the primary visual cortex

A

True

69
Q

Incoming LGN axons terminate almost exclusively in layer __ of 6 layered striate cortex. This forms a white line, known as ____

A

IV (4); Line of Gennari

70
Q

Fibers from upper visual fields project to cortex __ to calcarine sulcus

Fibers from lower visual fields project to cortex ___ to calcarine sulcus

A

inferior
superior

71
Q

What is the function of the ventral pathway that runs from striate cortex to temporal lobe?

A

High resolution form vision and object recognition

72
Q

A dorsal pathway runs from striate cortex to parietal lobe. This system is response for…

A

Spatial aspects of vision (analysis of motion)

73
Q

True or False: 80% of fibers sweep laterally and caudally to synapse in LGN of thalamus while 20% enter brachium of superior collicululus

A

True

74
Q

____ ____: orients movements of head and eyes

____: reflex control of pupil and lens

A

Superior Colliculus
Pretectum

75
Q

How do optic radiations (geniculocalcarine tract) maintain retinotopic organization?

A
76
Q

Which limb of the pupillary light reflex arc occurs when retinal relays from photoreceptors => bipolar => ganglion cells

A

Afferent Limb

77
Q

When cells in pretectal nucleus send axons to both Edinger-Westphal nuclei, which limb of the reflex arc is this?
A. Afferent
B. Association

A

B. Association

78
Q

True or False: Projection to contralteral Edinger-Westphal nucleus decussates in posterior commisure

A

True

79
Q

Cells in Edinger-Westphal nuclei send axons via CN III to postganglionic neurons in cilliary ganglia. Which limb of reflex arc is this?
A. Afferent
B. Association
C. Efferent

A

C. Efferent

80
Q

Where does the afferent limb terminate?

A

Tectum

81
Q

True or False: Pretectum sends axons to both EW nuclei

A

True

82
Q

Shining light into one eye causes constriction of both pupils because its ___

A

consensual

83
Q

In the efferent limb of reflex arc, ciliary ganglion cells innervate ___ ____ in iris, which results in b/l pupil constriction

A

sphincter pupillae

84
Q

If an affected eye shows no direct or consensual response to pupillary light reflect, this suggests lesion to which part of the reflex arc?

A

Efferent Limb

85
Q

____: The brain “sees” an out of focus object and reflexively binds it into focus; this reflex requires cerebral cortex

A

Accommodation Convergence Reflex

86
Q

Three features of accommodation convergence reflex (aka: near reflex)?

A
  1. Lens thickening
  2. Pupillary constriction
  3. Ocular convergence
87
Q

True or False: Argyll-Robertson pupils accommodate and react to light

A

False - they accommodate but do not react to light

88
Q

Argyll-Robertson pupils suggest lesion to…. and is specific sign of….

A

Pretectum; neurosyphillis

89
Q

What do the mneumonics ARP and PRA mean for Argyll-Robertson pupils?

A

ARP = Accommodation Reflex present
PRA = Pupillary reflex absent

Human Neuroscience (29 decks)

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