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OPT 531 - Ocular A&P + Biochem > Retina A&P > Flashcards

Retina A&P Flashcards

1
Q

RPE Intercellular junctions

A

Between RPE cells

  • Gap Junctions
  • ZA and ZO: Terminal Bar
  • Makes the RPE part of the blood-retinal barrier

Between RPE and Photoreceptors
-None! This creates a potential space, and is the location of retinal detachment. When a retinal detachment occurs, the photoreceptors are separated from nutrients supplied by the choroid, and can necrose

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2
Q

Location and consequences of retinal detachment

A

Location: between RPE and photoreceptor layer

Consequence: necrosis of the neural retina due to loss of access to choroidal nutrition

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3
Q

Rods vs. Cones: Pigment

A

R: rhodopsin

C: opsin’s for specific wavelengths

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4
Q

Rods vs. Cones: Disks

A

R: 600-1000, seperate from membrane

C: 1000-1200, folds of membrane

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5
Q

Rods vs. Cones: Terminations

A

R: spherules

C: pedicles, with lateral expansions called telondendria

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6
Q

Rods vs. Cones Renewal System

A

Rods
Disks are constantly produced at the base (inner segment). Disks move through the cilium and enter the outer segment. Disks move progressively towards the tip. Disks are sloughed in the morning and pagocytosed by the RPE

Cones

  • Same process
  • Disks continuous, not easily separated
  • Disks sloughed in the evening
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7
Q

How many disks are pagocytosed by an RPE cell every day?

A

1000-2000 disks

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8
Q

Myoid

A

Area of the photoreceptor inner segment that contains the golgi apparatus and endoplasmic reticulum

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9
Q

Ellipsoid

A

Area of the photoreceptor inner segment that contains mitochondira

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10
Q

Triad

A

Specialized junction consisting of a bipolar cell dendrite, flanked by two horizontal cell processes within an invagination of a photoreceptor terminal

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11
Q

Fiber baskets (of Schultze)

A

Apical villi of Muller Cells that terminate between inner segments of photoreceptors

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12
Q

Destination of P-type and M-type ganglion cells

A

P-type: parvocellular layers of the LGN

M-type: magnocellular layers of the LGN

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13
Q

Extent of Muller Cells

A

Extend from photoreceptor layer (apical) to internal limiting membrane (basal)

Basically, the entirety of neural retina

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14
Q

Muller Cells function

A
  • Provide structural support
  • Metabolize and store glycogen
  • Buffer by absorbing ions and neurotransmitters
  • Secrete factors that influence local blood flood and blood retina barrier
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15
Q

Microglia function

A

Phagocytic, roam the retina. Increase in response to inflammation or injury

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16
Q

Astrocytes

A

Absorb neurotransmitters in ganglion and nerve fiber layers

17
Q

Locations of Parafoveal and Perifoveal layers

A

Parafoveal: 0.5mm wide. Begins where INL is 12 cells thick and ganglion layer is 7 cells thick

Perifoveal: Begins where ganglion layer is 4 cells thick, and ends where it becomes 1 cell thick

18
Q

In clinic, the structure referred to as the fovea is histologically the

A

foveola

19
Q

In clinic, the structure referred to as the macula is histologically the

A

fovea

20
Q

Macular reflex results from

A

Walls of the macula (clinical definition)

21
Q

Foveal reflex results from

A

Floor of the macula (clinical definition)

22
Q

Macula Lutea diameter, location of center

A

Diameter: 5.5mm
Center Location
-3.5mm lateral
-1.0mm inferior

23
Q

Fovea diameter

A

1.5mm

24
Q

Foveola diameter, thickness

A

Diameter: 0.35mm
Thickness: 0.13mm

25
Q

Rod-Free-Area diameter

A

0.57mm

26
Q

Capillary-Free-Zone diameter

A

0.4-.05mm

27
Q

Parafoveal Area width

A

0.5mm

28
Q

Perifoveal Area width

A

1.5mm

29
Q

Optic Disk diameter

A

Horizontal: 1.7mm
Vertical: 1.9mm

30
Q

Blood supply to retina layers

A

Outer layers: choriocapillaris

Inner layers: retinal vessels

Outer plexiform layer is thought to be fed by both

31
Q

Location of blot-and-dot hemorrhages

A

Inner Nuclear Layer

32
Q

Location of flame-shaped hemorrhages

A

Nerve Fiber Layer

33
Q

Components of the blood-retina barrier

A

Fenestrations in the choriocapillaris allow large molecules to exit into choroidal tissue, which easily pass through Bruch’s membrane. ZO in the RPE prevent them from entering the retinal tissue

Retinal capillaries are non-fenestrated, and have ZO in their endothelium, preventing large molecules from entering the retina

34
Q

Sequence of filling in choroidal and retinal vessels in fluorescein angiography

A

Dye is injected, series of photos are begun

Within seconds, choroidal flush
–> If RPE is defective, dye seeps into retina now

6-8 seconds: retinal arteries fill, core first, then outer wall

Next retinal capillaries

10sec-1min: retinal veins fill, wall first, then core

Leakage of vessels will be evident with dye

35
Q

Number of cones, rods, and ganglion cells in the human retina

A

Cones: 4-5 million
Rods: 80-110 million
Ganglion Cells: 1 million

OPT 531 - Ocular A&P + Biochem (4 decks)

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