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OPTM 5032 - Ocular Physiology > The Retina > Flashcards

The Retina Flashcards

1
Q

Ten Layers of the Retina

A
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2
Q

The retina extends over what portion of the globe?

A

posterior 2/3 of the globe

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3
Q

The retina is internally bound by?

A

the vitreous body

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4
Q

The retina is externally connected to?

A

Bruch’s membrane

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5
Q

When does the retna lose the reddish color and turn gray/opacify?

A

~ 1 hour after death

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6
Q

What detects light and movement in the retina?

A

Rods

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7
Q

What provides color and form vision in the retina?

A

Cones

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8
Q

What is the internal background of the eye?

A

Fundus Oculi

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9
Q

What color is the fundus oculi?

A

Orange-red color derived from the choroidal blood vessels and the retinal pigment epithelium

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10
Q

In fair subjects is the fundus oculi lighter or darker? Darker subjects?

A

Fair - Lighter fundi

Darker - Darker, grayish fundi

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11
Q

When looking at the fundus oculi in albinos what is seen?

A

White scleral tissue is exposed, one sees choroidal vessels through the retina

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12
Q

Where does the optic nerve leave the eye?

A

At the optic disc or papilla

located 3mm medially to and slightly above the posterior globe

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13
Q

What is the optic disc completely devoid of causing the blind spot?

A

Photoreceptors

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14
Q

Where is the fovea centralis located and how big is it?

A

Temporal to and below the posterior pole

1 - 2 mm in diameter

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15
Q

At the fovea centralis retinal (thinning/thickening) produces a _____ _____ in the surface where the nerve elements are heaped to formed _____ ____

A

Thinning

Shallow Depression

Henle’s Layer

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16
Q

How big is the foveola?

A

0.35 mm in diameter, within the fovea

17
Q

Where are the cones contained?

A

In the foveola

18
Q

Where is the macula lutea found?

A

Around the fovea centralis

(yellow spot - yellowish pigment xanthophyll)

19
Q

The ora serrata separates what?

A

Separates the neural part of the retinal periphery from the ciliary body

20
Q

Where does the ora serrata lie?

A

8.5 mm behind the limbus

6 mm in front of the equator

21
Q

What are thinner and lighter in the retina (veins/ arteries)?

A

Arteries

22
Q

Are anastomoses found in the retina?

A

No

23
Q

Does the fovea contain any vessels?

A

The fovea is free of obstruction from blood vessels

24
Q

What are the four subdivisions in the retina?

A
  1. Pigment Epithelial Layer
  2. Photorecepter Layer
  3. The Intermediate Layer
  4. The Ganglion Cell Layer
25
Q

What does the the pigment epithelial layer (RPE) form?

A

Forms a single stratum of epithelial cells attached to Bruch’s membrane

(There are about 5 million in each eye)

26
Q

Pigmented projections intrude where in the pigment epithelial layer? What do they do?

A

between adjacent rods and cones

Protect receptors from excessive and scattered light

27
Q

Is mitosis demonstrated in the pigment cells?

A

No

28
Q

Each pigment epithelium cell is in contact with an average of up to how many photoreceptors?

A

45 photoreceptors

29
Q

What are the functions of the pigment epithelial layer?

A

FUNCTIONS:

  1. Absorption of light and removal of heat
  2. Restricts stray light; protects receptors from undesirable effects of light
  3. Provides photoreceptors with nutrients/ O2
  4. Reservoirs of useful substances (ex. Vit A)
  5. Provide slow disintegration, a role in phagocytotic activity
30
Q

Is there a connection between the RPE and receptors? Why?

A

No anatomical connection exists

Leads to the ease with which two layers can be deteched

31
Q

What are photoreceptors?

A

Sensory cells that transform light into electrical energy by chemical processes

32
Q

What type of arrangement do photoreceptors have?

A

Palisade arrangment (parallel pickett fence appearance)

Held in position by the external limiting membrane

33
Q

What is the size of rods?

A

Long (40-60 um)

Slender (2 um)

34
Q

Where is the photosensitive part of the rods?

A

The outer segment

35
Q

What is contained in the outer segment?

A

Rhodopsin (photopigment)

600 - 1000 loosely stacked disc units (lamellae)

36
Q

Lamellae are formed at what rate?

A

1-5 per hour at the bottom of the segment

37
Q

When do rods slough?

A

In the morning or in the light after long dark periods

(in a group of 30 from top of segment)

38
Q

How long does it take for rod lamellae to be completely renewed?

A

1-2 weeks

39
Q
A

OPTM 5032 - Ocular Physiology (9 decks)

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