Lecture 78 Flashcards

1
Q

_______ is the visual field of a prey animal

A

320 degrees

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2
Q

_______ is the visual field of a predator

A

250 degrees

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3
Q

_______ is the depth perception?

A

binocular field

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4
Q

_______ is the simple term for refraction

A

light bends

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5
Q

each visual field represented in the _______ optic tract

A

contralateral

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6
Q

The closer together the eyes the more input each eye gets from _______

A

BOTH visual fields

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7
Q

If an animal has an increased medial eye placement (predators) they have an increased _______?

A

Binocular vision

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8
Q

If an animal has an increased binocular vision they have a _______ percent of decussation at optic chiasm

A

decreased

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9
Q

Predators have a _______ percent of cross over/decussation

A

less

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10
Q

_______ are the three layers of the eye?

A

Fibours, Vascular (Uvea) and Nervous

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11
Q

_______ is apart of the fibours portion of the eye?

A

cornea and sclera

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12
Q

_______ is apart of the vascular (uvea) portion of eye

A

Choroid, ciliary body, iris

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13
Q

_______ is apart of the nervous portion of the eye

A

retina

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14
Q

Light is _______ as it passess through the the cornea and lens

A

refracted

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15
Q

light passing through the center of the cornea is _______ bent

A

NOT

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16
Q

Light is upside down and _______ on retina

A

reversed

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17
Q

_______ reflects light more than lens does

A

Cornea

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18
Q

lens _______s the image

A

Fine-tunes

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19
Q

to accommodate light the _______ of the lens can be altered

A

shape

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20
Q

to accommodate light _______ and _______ also help

A

suspensory ligaments and ciliary muscles

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21
Q

Lens can change shape and become rounder to _______ refraction for near vision or _______ for distance vision

A

Increase, thinner

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22
Q

_______ layer in choroid that increases light detection in dark conditions

A

Retroreflective

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23
Q

_______ is the retroreflective layer

A

tapetum lucidum

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24
Q

_______ layer is this: Absorbs light and prevents light scatter between photoreceptors; Convert trans-retinal to cis-retinal needed by photopreceptors

A

Pigment cell layer

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25
Q

_______ layer is this: Outer portion of rods and cones that contain light sensitive pigments

A

Photoreceptor layer

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26
Q

_______ layer is this: Cell bodies and nuclei of rods and cones

A

Outer nuclear layer

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27
Q

_______ layer is this: Synapses of photoreceptor cell axon terminals with dendrites of retinal interneurons (bipolar and horizontal cells

A

Outer plexiform layer

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28
Q

_______ layer is this: Cell bodies of retinal interneurons; Bipolar cells (B), Horizontal cells (H), Amacrine cells (A)

A

Inner nuclear layer

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29
Q

_______ layer is this: Synapses of retinal interneuron axon terminals with dendrites of ganglion

A
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30
Q

cells

A

Inner plexiform layer

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31
Q

_______ layer is this: Cell bodies of ganglion cells (G); These are the ‘output’ cells of the retina

A

Ganglion cell layer

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32
Q

_______ layer is this: Axons of ganglion cells traversing, the inner retina on their way to, the optic disk to the optic nerve

A

Optic nerve layer

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33
Q

Reflective layer in choroid thatincreases light detection in darkconditions

A

Tapetum lucidum

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34
Q

Retinal pigment epithelium lacks _______ overlying tapetum

A

melanin

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35
Q

Tapetum lucidum: Allows light to pass through and reflect back to stimulate _______

A

photoreceptors

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36
Q

Outer segment: contains photopigments specialized toabsorb light

A

Rod cell

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37
Q

_______ is involved in the rod cells that help absorb light?

A

Rhodopsin

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38
Q

Low threshold; Contains Retinal (Vit A derivative) in combination with anopsin (G-protein coupled receptor)

A

Rhodopsin

39
Q

(color, photopic, or day vision)

A

Cone cell

40
Q

_______ are the outer segment tapers of the cone cells

A

Photopsins or Iodopsins- higher threshold

41
Q

_______ is the pathway for conscious perception of vision?

A

Optic nerve, Optic chiasm, optic tract

42
Q

the optic chiasm is the _______

A

Cross over (double decussation)

43
Q

this nucleus is located in the Diencephalon in the thalamus and is the 3rd order neuron

A

lateral geniculate nucleus

44
Q

The lateral geniculate nucleus (LGN) is needed for?

A

Vision

45
Q

The dicephalon has the LGN and the

A

Subcortical

46
Q

Axons of LGN neurons in optic radiation is in the

A

cerebral cortex

47
Q

Axons of LGN in cerebral coretx: Visial cortex in _______

A

occipital lobe

48
Q

Cerebral cortex: Axons of LGN neurons in optic radiation to visual cortex in occipital lobe to visual association areas of the _______ lobes

A

parietal and temporal

49
Q

_______ work best in dim light/dark conditions

A

Rods

50
Q

One photon of light can activate a rod, many needed to activate a cone due to ?

A

greater sensitivity and amount ofphotopigment in rods

51
Q

Light causes rods and cons to become _______

A

Hyperpolarized

52
Q

Many rods converge on one _______

A

bipolar cell

53
Q

Bipolar cell more likely to be activated by low levels of light due to _______

A

convergence of rod

54
Q

One cone or just a few cones converge onone bipolar cell, so there is _______ of cone pathway to light

A

less sensitivity

55
Q

Optic tract contains a mixture of _______

A

‘PLR’ and ‘vision’ fibers

56
Q

PLR’ (Pulpillary light response) fibers (20%) go to midbrain pretectal nucleus and move to _______

A

rostral colliculus (bypass the LGN)

57
Q

Vision fibers (80%) goes to the _______ in the thalamus

A

LGN

58
Q

PLR is subcortical (midbrain) reflex inducing _______ pupil constriction

A

parasympathetic induced

59
Q

Phototransduction: Conversion of cis to trans-retinal changes shape of _______

A

G-protein

60
Q

Phototransduction: Conversion of cis to trans-retinal changes shape of G-protein. _______ happens next?

A

PDE degrades cGMP

61
Q

Light stimulates _______ on R receptors to activate phototransduction

A

Rhodopsin

62
Q

Phototransduction: Once PDE degrades cGMP _______ happens next?

A

cGMP gated Na+ channels close

63
Q

Phototransduction: cGMP gated Na+ channels close. _______ happens next?

A

Hyperpolarize the cell and decrease glutamate release (NT)

64
Q

Photon activates phosphodiesterase so Na cannot come in (no depolarizing) causes a _______ bc there is still active K+ channels

A

hyperpolarizing

65
Q

Light activates _______ in photoreceptors

A

Pigment molecules

66
Q

Phototransduction: Light converted to

A

electrical signal

67
Q

In the dark, rhodopsin contains _______

A

cis-retinal

68
Q

Light absorption causes transformation to _______, which dissociates from opsin(bleaching reaction

A

trans-retinal

69
Q

Light absorption causes transformation to trans-retinal, which dissociates from _______

A

opsin (bleaching reaction)

70
Q

_______ converts 11 cis-retinal to all trans retinal when light is seen

A

photoisomerization

71
Q

11 cis-retinal is convert to all-trans retinal by photoisomerizes _______ is turned into all-trans retinal

A

Metarhodopsin II

72
Q

When all-trans retinal is created GPCR tranducin is activated which activated ?

A

PDE (phosphodiesterase)

73
Q

PDE once activated changes _______

A

cGMP

74
Q

So when there is more light there is more PDE which means there is _______

A

LESS cGMP

75
Q

Light indirectly decreases _______?

A

cGMP

76
Q

When there is PDE _______

A

cGMP-gated channels close

77
Q

When the cGMP-gated channels close there is a decrease in Na and a decrease in glutamate which causes?

A

Hyperpolarization

78
Q

There is an increased _______ release at rest (no light) so there is more cGMP so the cells are depolarized

A

Glutamate

79
Q

Steady _______ hyperpolarizes cell

A

K+

80
Q

Photoreceptor membrane potential changes when there is a decrease in cGMP. The more light the _______

A

less cGMP

81
Q

During a dark current (-40mv) there is a steady _______

A

inward Na+

82
Q

The cells are _______ in the DARK

A

depolarized (bc Na is coming in)

83
Q

In the dark there is an increase in _______ release

A

glutamate

84
Q

When do rods work the best?

A

Dark/dim rooms

85
Q

Why are bipolar cells more likely to be activated by low levels of light?

A

Due to convergence of rods (scotopic vision)

86
Q

_______: Tranduction (one rhdopsin molecule can activate 100s of transuction molecules0 each of which stimulate PDE

A

Amplification

87
Q

_______ protein blocks the ability of activated rhodopsin to activate transduction

A

Arrestin

88
Q

cGMP is outer segments is modulated by

A

light and Ca2+

89
Q

Ca2+ has _______ on guanylate cyclase

A

Inhibitory effects

90
Q

During blinding bright light all cGMP channels are _______ and photoreceptors are _______

A

CLOSED, Saturated

91
Q

The _______ tests the retina goes to optic nerve (II) then to optic chiasm then optictract then to visual cortex then to facial nerve(VII) nucleus in medulla

A

menace reflex

92
Q

The menace response is a learned response and is a

A

cortical response

93
Q

Initiates compensating eyemovement to keep vision fixedwhen head turns

A

Vestibulo-ocular reflex

94
Q

Rostral colliculus in midbrain; Decussates; Descends cord in tectospinal tract; Contraction of neck muscles to turn towards stimulus

A

Visual startle reflex