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Neuroscience > Retinal Transduction Lec11 > Flashcards

Retinal Transduction Lec11 Flashcards

1
Q

what is the fovea? the small depression at center of macula with the ___

A

highest spatial acuity

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2
Q

what enters and leaves the optic disk?

A

blood vessels enter and retinal axons leave the eye

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3
Q

: ant. ciliary and long post. ciliary arteries supply blood to the

A

iris and ciliary body

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4
Q

Uveal tract consists of three structures:

A

choroid, the ciliary body and the iris.

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5
Q

Delivery of metabolic substrates and oxygen to the retina is accomplished by (2)

A

the inner retinal and choroidal.

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6
Q

what is the posteriro chamber

A

Region between the vitreous and the lens.

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7
Q

what produces aqueous humor?

A

the vascular component of the ciliary body.

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8
Q

where is the vitreous humor

A

the space between the back of the lens and the surface of the retina.

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9
Q

what pigment does the macula contain?

A

a yellowish pigment (xantophyl). Supports high acuity.

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10
Q

The ocular vessels are derived from the

A

all from the ophthalmic artery (OA),

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11
Q

what are the two distinct vasciualr systems that supply the eye

A

a) the anterior segment (iris and ciliary body)
b) the retinal systems.

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12
Q

Focusing Power of a lens =

A

Curvature of surface + differences in Refractive Indexes

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13
Q

focal length - how strongly a lens ___

A

converges light.

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14
Q

Greater lens curvature = Greater converging power = __ focal length

A

Shorter

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15
Q

diopters - measure of

A

optical power.

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16
Q

dipopeter =

A

1/focal length

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17
Q

emmetropic eye - is

A

elaxed, unaccommodated, focused on object at “infinity”

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18
Q

what is responsible for most of the refraction in the eye

A

Cornea - 80%

lens does 20%

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19
Q

Refractive index of cornea =

A

1.37

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20
Q

accommodation - the___ to focus on near objects

A

curvature of the lens increases

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21
Q

what muscles contract to increase the curvature of the lens? which relax?

A

ciliary muscles contract, zonule fibers relax

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22
Q

when the curvature of the lens increases the focal length

A

decreases

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23
Q

Accommodative triad/near reflex:

A

eye accomm. + pupil constriction + eye convergence

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24
Q

eye accomm. + pupil constriction is mediated by the

A

parasymp. nerves from Edwin Westphal nucleus of pretectum

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25
Q

The ___ lens is transparent, has crystallins, with high refractive index of 1.42,

A

crystalline

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26
Q

• cataract - disorder of___ that destroys lens transparency,

A

lens cell fibers or aggregation of crystallin

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27
Q

___ is the leading cause of blindness worldwide.

A

cataracts

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28
Q

risk factors for cataracts

A

aging, diabetes, sunlight, smoking

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29
Q

sx of cataracts

A

hazy vision, poor night vision, glare, faded colors

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30
Q

tx of cataracts includes

A

surgical replacement with an artificial lens

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31
Q

presbyopia - inability to focus on _____ objects

A

near

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32
Q

Refractive errors prevent light from

A

focusing on the retina

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33
Q

myopia / nearsightedness is caused by the

A

cornea too curved or eyeball too long

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34
Q

with myopia the light is focused ___

A

in front of the retina

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35
Q

nearsightedness is called

A

myopia

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36
Q

with -hyperopia / farsightedness the cause is the

A

cornea not curved enough or eye too short

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37
Q

with hypoerpopnia the light is focused

A

behind the retina

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38
Q

you correct hyperopia with

A

(+)/convex lens

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39
Q

you fix myopia with a

A

concave lens

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40
Q

Aqueous humor nourishes the__ and ___

A

cornea and lens

41
Q

aqueous fumor is secreted by the

A

epihtelium

42
Q

Aqueous humor

flows from anterior chamber angle of eye
to…

A

Leaves the eye by passive flow at the anterior chamber angle

43
Q

Flow of aqueous humor against resistance generates ___.

A

intraocular pressure (IOP) of ~15 mmHg

44
Q

Glaucomas = damage to the ___ that can result in vision loss and blindness

A

optic nerve

45
Q

risk factors for glycoma

A

high IOP, thin cornea, abnormal optic nerve, HTN, cardiovascular disease, diabetes

46
Q

glaucoma causes loss of ___ fields

A

peripheral

47
Q

tx of gluacoma?

A

treat with

  1. eyedrops to decrease aqueous production or increase drainage

or

  1. surgery
48
Q

where are photoreceptor cell bodies found?

A

outer nuclear layer

49
Q

order light passes through to get to the photoreceptor

A
  1. ganglion cell layer
  2. inner plexiform laer
  3. inner nuclear layer
  4. outer plexiform layer
  5. out nuclear layer
50
Q

cells in inner plexiform layer

A

bipolar / amacrine / ganglion cells synapse

51
Q

cells in inner nuclear layer

A

bipolar / amacrine / horizontal cell bodies

52
Q

cells in outer plexiform layer

A

photoreceptor / bipolar / horizontal cells

53
Q

function of pigment epithelium?

A

backstop for light, regenerate pigment, nourish and regenerate photoreceptors

54
Q

pigment epithelium in the back of the eye contains ___ pgiment

A

melanin

55
Q

a lens with a short focal length has ___ focal power

A

greater

56
Q

Focal distance is ___ proportional to the curvature of the lens.

A

inversely

57
Q

loss of ___ with cage causes presbyopia

A

lens elasticity

58
Q

A diopter of accommodation is defined as

A

1/distance to the object

59
Q

. A near object at 1 m requires accommodation of ___

A

1 D

1/ ( distance to object)

60
Q

___ requires a positive lense

A

hypermetropia (positive is a convex lens)

61
Q

Myopic correction using the excimer laser is based on a graded removal of____ tissue to decrease the central anterior corneal curvature.

A

central anterior corneal

62
Q

___ correction is based on a graded removal of a peripheral and paracentral anterior corneal curvature.

A

Hyperopic

63
Q

glaucoma

Open angle: Slow development of pathology caused by obstruction of the___

A

drainage canals

64
Q

glaucoma

Close angle: Sudden increase in intraocular pressure. Closed or___

A

narrow angle between the iris and cornea.

65
Q

where does phototransduction occur

A

in the outer photoreceptor segments

66
Q

photic input is transmitted to the brain by the spiking discharge pattern of the____ via the optic nerve.

A

ganglion cells

67
Q

Retinal glia cells include

A

astrocytes

microglioa

mueller cells

68
Q

Vertical information flow:

A

photoreceptorsbipolar cellsganglion cells

69
Q

Lateral information flow:
Is mediated by

A

horizontal cells and amacrine cells

70
Q

Cells along the vertical path (photoreceptors, bipolar and ganglion cells) release ___

A

glutamate

71
Q

Cells mediating lateral information transmission (horizontal and amacrine cells) release mostly

A

GABA or glycineric

72
Q

rods and cones are ___

A

photoreceptors

73
Q

rods and cones use what NT

A

glutamate

74
Q

Photoreceptors in the ___ have a standing/circulating current

A

Dark

75
Q

Dark

__ and ___ influx at outer segment: depolarization

A

Ca and Na

76
Q

Dark

___ at inner segment: hyperpolarization

A

K efflux

77
Q

in the dark, the photoreceptor is constantly

A

staying depoalrized and -40 and releasing glutamate

78
Q

Photoreceptors respond to Light by suppressing the ___

A

inward, cationic current

79
Q

rhodopsin = pigment in ___

A

rods

80
Q

cone opsin = pigment in ___

A

cones

81
Q

Photon absorption makes 11-cis retinal to

A

all-trans

82
Q

11-cis retinal to all-trans, activates –>

A

rhodopsin (rods) or opsin (cones)

83
Q

Rhodopsin* initiates signal cascade (via transducin and PDE) that___

A

decreases cGMP

84
Q

1 Rhodopsin ___ lots of cGMP –> closes 200+ cGMP channels

A

hydrolyzes

85
Q

↓ cGMP in outer segment –>

A

Na and Ca gates close

86
Q

how does light cuase less Glu release?

A

Rhodopsin dec cGMP > Na and Ca gates close -

-> ↓ Na and Ca influx (but K efflux continues) –> h

yperpolarization –> ↓ Glu release & ↓ intracellular Ca

87
Q

____ is the ability of photoreceptors to adjust to the ambient level of light

A

Light Adaptation

88
Q

light adaption occurs in Occurs in __ and ___

A

photoreceptors & in postsynaptic retinal cells

89
Q

what happens at saturation?

A

all cGMP-gated channels are closed, photoreceptors cannot respond to further light

90
Q

rods are cones are very senstiive to light

A

rods

91
Q

mutation in rod proteins causes ___

A

retinitis pgimentosa

92
Q

night blindess, tunnel vision, often legally blind by 40 are sx of

A

retinitis pgimentosa

93
Q

1 cone to __ bipolar cell

A

1

rods have a much higher convergence

94
Q

rods or cones mediate high acuity vision?

A

cones

95
Q

wet
blood vessels behind retina grow and leak
dry
degeernation of epithelium and photorceptors, causing dursen build

A

age related macular degeration

96
Q

lose: central vision and acuity

A

age related macular degeration

97
Q

LGN enters V1 and terminates in___

A

layer 4

98
Q

Ouputs to higher areas of v1 is by ___

A

pyramidal cells

99
Q
A

Neuroscience (35 decks)

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