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The Visual System > The Retina > Flashcards

The Retina Flashcards

1
Q

How many layers does the retina consist of?

A

9

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2
Q

Light passes through the entire layer of the retina prior to what?

A

stimulating rods and cones.

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3
Q

What are rods and cones for?

A

To perceive light.

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4
Q

What is the macula?

A

An oval shaped and highly pigmented yellow spot in the central portion of the retina.

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5
Q

What does the macula surround?

A

The fovea, parafovea, and perifovea.

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6
Q

What does the macula serve as?

A

A protective filter over the fovea.

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7
Q

What does the macula contain?

A

xanthophylls, carotenoids, lutein

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8
Q

What does the macula observe?

A

Excess light entering the eye including UV rays.

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9
Q

Where is the fovea?

A

A small indented area of the center of the retina.

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10
Q

What does the fovea contain, in terms of rods and cones?

A

it has only cones and a few or NO rods.

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11
Q

What is in the central portion of the fovea or foveola?

A

Has exclusively cones that are more tightly packed than other areas.

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12
Q

What are characteristics of the cones in the foveola?

A

They are uniquely long and slender.

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13
Q

What characteristics do cones in the peripheral area contain?

A

They are usually wide

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14
Q

What surrounds the fovea?

A

The parafovea and the perifovea

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15
Q

The structure of the fovea prevents what?

A

significant reduction of visual acuity.

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16
Q

Where is the pigment epithelium?

A

The outermost layer of the retina.

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17
Q

The pigment epithelium is not apart of what?

A

The neurosensory of the retina.

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18
Q

What does the pigment epithelium contain?

A

single layer of hexagonal cells densely paced with dark or brown granules.

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19
Q

What do the granules of the epithelium contain?

A

Melanin and lipofucsin.

20
Q

What is lacking in albines in the retinal pigment epithelial?

A

pigment granules.

21
Q

How are the pigment epithelial cells arranged?

A

extend straight threadlike processes between the rods and cones.

22
Q

What does the cytoplasm of the pigment epithelial cells contain?

A

Vitamin A .

23
Q

What vitamin is present in the cytoplasm of rods and cones as well?

A

Vitamin A

24
Q

What does the pigment epithelium prevent?

A

Light reflection throughout the eyeball

25
Q

What does the pigment epithelium absorb?

A

Excess light at the back of the retina and prevents the reflection of the light back inwards.

26
Q

What does the reflection of light back inward of the pigment epithelium prevent?

A

image degradation.

27
Q

What does the pigment epithelium nurture?

A

Rods and cones by supplying nutrients such as amino acids, ascorbic acid, and glucose.

28
Q

What does the pigment epithelium remove?

A

The outer segment of rods and cones that are worn out by phagocytosis.

29
Q

What serves as a physical barrier between neurosensory retina and substances in choroidal blood?

A

Pigment epithelium

30
Q

How does the pigment epithelium maintain homeostasis?

A

Uses a delicate transport exchange system to maintain ionic homeostasis.

31
Q

In a defective retinal pigment epithelium will result in what?

A

Night blindness

32
Q

What is the clinical name for night blindness?

A

Nyctalopia

33
Q

What is night blindness/ nyctalopia?

A

very difficult to see in low light environment and will result in insufficient adaptation of dark.

34
Q

Tunnel vision and blindness are associated with what?

A

Defective retinal pigment apithelium

35
Q

All rods and cones share some features which are what?

A

outer segment, inner segment , nucleus and synaptic body.

36
Q

What do the outer segments of the rods and cones contain?

A

Photopigments/ Photoreceptors

37
Q

What do the photopigments contain?

A

conjugated proteins containing opsin and a vitamin A derivative.

38
Q

What is the name of the vitamin A derivative?

A

Retinal

39
Q

Where are the photopigments of the outer segments inserted?

A

in the membranous discs as transmembrane proteins.

40
Q

What are the membranous discs made up out of?

A

infolded membranes.

41
Q

What are the membraneous disks lined with?

A

Photopigments that contain opsin and vitamin A derivative.

42
Q

What does opsin activate?

A

G protein.

43
Q

The outer segment interdigitates with what?

A

membrane extensions of cells in the retinal pigment epithelium.

44
Q

What does the inner segment contain?

A

organelles similar to other somatic cells and have abundant mitochondria.

45
Q

Why is abundant mitochondria necessary for inner segments of the rods and cones?

A

For high energy required by both rods and cones.

46
Q

What is the synaptic body?

A

It connects with other cells in the neurosensory retina with bipolar and horizontal cells.

The Visual System (9 decks)

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