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Organ systems > Retina > Flashcards

Retina Flashcards

1
Q

What is the nervous coat of the orbit called?

A

Retina

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2
Q

What must light pass through to reach retina? 4

A

cornea, aqueous humor, lense, vitreous body

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3
Q

What is the fovea centralis?

A

central point of retina with only cones

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4
Q

What does the abundance of cones in fovea do?

A

gives high level of visual aquity

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5
Q

Maculua lutea

A

Yellow area surrounding fovea

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6
Q

what gives maculua lutea its yellow color?

A

Accumulation of lutein and zeaxanthin, carotenoids

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7
Q

what do the carotinoids of the maculea do?

A

antioxidant activity, absorb excess blue/ultraviolet light.

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8
Q

why is there a blind spot?

A

The optic dist is where axons and central artery exit the orbit, there are no receptors.

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9
Q

What supplies blood to retina?

A

Brance of internal carotid, the central artery.

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10
Q

What surface of retina does central artery exit onto?

A

Central artery exits onto the inner surface of retina

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11
Q

What are the 4 retinal layers?

A

RPE retinal pigmented epithelium, Photo receptors, neural cells and ganglion cells

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12
Q

What do photo receptors do?

A

absorb visible light

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13
Q

What do neural cells due?

A

they integrate light information,

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14
Q

What form are neural cells?

A

bipolar, (horizontal and amarcrine)

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15
Q

Job of ganglion cells?

A

project visual information to thalamus, superior colliculus and more, their axon leaves the eye

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16
Q

What does the outer layer of rods and cones contain?

A

stacks of pigmented disks.

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17
Q

Pigmented disks in rods?

A

rhodopsin

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18
Q

Pigmented disks in cones?

A

iodopsin

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19
Q

what does the inner segment of photoreceptors, the part with the nucleus contain?

A

synaptic terminal that releases glutamate

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20
Q

Visable light is part of whats frequency spectrum

A

electromagnetic radiation

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21
Q

where are the pigments in photoreceptors located?

A

inside vescular disks on the terminal end

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22
Q

What spectrum of visable light do pigments respond to?

A

450 - 700 nm

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23
Q

What happens to photo receptor upon exposure to light?

A

Hyperpolarization that inhibits release of glutamate

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24
Q

What channels close to hyperpolarize cell?

A

Na and Ca++

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25
Q

what type of messenger signal closes the channels to cause hyperpolarization?

A

Opsin activates Phosphodiesterase PDE via a transducen

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26
Q

What type of messenger is transducen?

A

G protein

27
Q

Light converts retinal how?

A

from cis retinal to trans retinol

28
Q

Photopic

A

vision in bright light, low sensitivity

29
Q

Scotopic

A

vision in dim ligh, highly sensitivity, night vision

30
Q

What receptor is photopic?

A

cones, best in bright light

31
Q

What receptor is scotopic?

A

rods, good for ight vision

32
Q

What receptor gives the best acuity?

A

cones, because they are concentrated in fovea

33
Q

what gives best spacial resolution, ie acuity?

A

cones

34
Q

What receptor is achromatic?

A

cones,, color vision through 3 pigmented cells.

35
Q

What receptors are more sensitive to scattered light?

A

rods, good for ight vision

36
Q

What receptor is better at detecting visual motion?

A

rods.

37
Q

Where are cones in the retina?

A

everywhere but they are most abundant in the fovea

38
Q

Where are rods in the retina?

A

The are not in the fovea but are extreamly abundant everywhere else.

39
Q

Why would the fovea have the most cones?

A

because it is the center of the visual field. So wants the best visual aquity

40
Q

How are cells arranged in the fovea?

A

The shallower cells, the ganglion and bipolar cells are pressed away to the side allowing light more direct acess to the cones for increased acuity

41
Q

Why is it good that the photo receptors are so deep in the retina?

A

IT puts them closest to the choroid body

42
Q

Why do rods and cones need to be near blood supply, choroid body?

A

because pigment turnover requires lots of oxygen

43
Q

How does light get past the ganglion and bipolar cells?

A

light passes through them, they refract just like aqueous humor

44
Q

What is the layer deep to the photoreceptors?

A

retinal pigment epithelium RPE

45
Q

What are the 5 jobs of the RPE?

A

Visual acuity, antioxidant, maintain photoreceptor excitability, nutrients provider, phagocytosis of cell debries

46
Q

How does RPE effect visual acuity?

A

limits reflection of light back to receptors after the first pass, prevents blurred image

47
Q

Why would RPE absorbe blue light?

A

blue light increases free radical formation in retinal cells

48
Q

what brings retinol to photoreceptors?

A

RPE retinal pigmented epithelium, Photo receptors, neural cells and ganglion cells

49
Q

what would deficient uptake of membrane fragments cause?

A

separation of receptors from choroid.

50
Q

if receptors separate from RPE, what would happen?

A

anoxia and cell death

51
Q

why is fovea avascular?

A

improved acuity without vascular interference

52
Q

how does waste and water get transported from extracellular space at fovea to choroid?

A

Membrain transporters in the RPE

53
Q

Why is retinal detachment relatively easy?

A

Attachment of REP to photoreceptors is unstable, there is nothing physically keeping them together.

54
Q

What can cause retinal detachment, 2?

A

Buildup of cellular waste under the retina or leaking blood vessels under RPE

55
Q

What is detached retina called?

A

macular degeneration

56
Q

What does optic nerve consist of? 3

A

Axons of ganglion cells, GLIAL cells, central artery and vein

57
Q

Why should optic nerve be called tract?

A

Because it has menegies just like the CNS

58
Q

What type of CNS glia does optic nerve have?

A

Oligodendrocytes and astrocytes

59
Q

oligodendrocytes do what?

A

myleinate axons

60
Q

astrocytes do what?

A

surround cell bodies and dendrites, and also contract blood vessels.

61
Q

Papilledema

A

increased CSF pressure that limits venous return from retina causing edema under optic disc.

62
Q

how to idea papilledema?

A

blurred disk margin when viewed with opthalmoscope

63
Q

What does papilledema do in additon to edema under optic disk?

A

Expaned CSF space around CN II, More veins in eye, axoplasmic stasis of ganglion cells.

64
Q

why do we not notice our blind spot?

A

binocular vision, info within blind spot is interpolated from adjacent areas of retina during eye movements or by visual cerebral cortex activty.

Organ systems (14 decks)

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