RETINA Flashcards

1
Q

Layers of the retina.

A
  1. RPE- retinal pigmented epithelium
  2. Photoreceptor layer.
  3. External limiting membrane.
  4. Outer nuclear layer.
  5. Outer plexiform layer.
  6. Inner nuclear layer.
  7. Inner plexiform layer.
  8. Ganglion cell layer.
  9. Optic nerve fiber layer.
  10. Internal limiting layer.
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2
Q

RPE

A

Retinal pigmented epithelium. The outermost retinal layer- creating the non-sensory retina. Lays between choroid and photoreceptor layer and contain melanin granules. It’s dark brown except for the part with tapetum. The main role of that layer is to provide nutrition for the neurosensory retina, recycling of the bleached ‘used’ photopigment, storage of the vitamin A, phagocytosis, absorb stray light and free radicals.

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3
Q

Photoreceptor layer.

A

Outer segments of rods and cones that contain stacked discs with photopigment, and part of the inner segments with mitochondria. Here’s where transduction of light stimulus happens.

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4
Q

Outer nuclear layer.

A

Cell bodies of rods and cones.

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5
Q

Outer plexiform layer.

A

Synaptic connections between photoreceptors and bipolar, amacrine and horizontal cells.

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6
Q

Inner nuclear layer.

A

Cell bodies of horizontal, bipolar, amacrine and Mullers cells.

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7
Q

Inner plexiform layer.

A

Is the second synaptic layer between axons of amacrine, bipolar, horizontal cells and retinal ganglion cells.

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8
Q

Ganglion cell layer.

A

cell bodies of the RGCs, usually one cell thick, axons of these cells run parallel to the retina and converge onto the optic disc.

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9
Q

Nerve fibre layer.

A

Axons of the RGCs that run parallel to the retina and converge onto the optic disc.

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10
Q

Internal limiting layer

A

Basement layer, the border between the retina and vitreous.

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11
Q

Types of cells that form neuro-retina.

A

Rods, cones, amacrine, horizontal, bipolar, interplexiform neurons, Muller’s cells, retinal ganglion cells.

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12
Q

Blood supply to the retina.

A

Dual blood supply (as the most metabolically active tissue in the body). 1- Choroid vessels that supply outer retina and 2- retinal vessels that supply mid and inner retina 2- in most mammals, they’re branches of posterior ciliary arteries called cilioretinal arteries and penetrate the sclera in a circle around the optic disc.

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13
Q

Patterns of retinal vasculature.

A

Holangiotic- whole retina is transversed with vessels.
Merangiotic- laterally and medially extending vessels.
Paurangiotic- short vessels, radiating around the optic disc.
Anangiotic- no vessels.

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14
Q

Holangiotic retina- pattern and which animals.

A
The whole inner retina receives a direct blood supply, either from a central artery (primates) or from cilioretinal arteries that emerge as several branches from or around the optic disc.
Most mammals (including dog, cat, sheep, cow, rat, mouse, primates and some marsupials)
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15
Q

Merangiotic retina- pattern and which animals.

A

Blood supply localized to the nasal and temporal parts of the inner retina.
Rabbit, pika.

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16
Q

Paurangiotic ratina- pattern and which animals.

A

The vessels are minute and extend only a short distance from the optic disc, leaving most of the inner retina avascular.
Horse, rhinoceros, elephant, guinea pig

17
Q

Anangiotic retina- pattern and which animals.

A

Devoid of vessels.
Most non-mammalian species: birds, reptiles, amphibians.
From mammals- most marsupials, beaver, chinchilla, porcupine, armadillo, sloth, bats.

18
Q

What is characteristic in avian retina.

A

The presence of pecten- structure that protrudes into the vitreous from the retina.

19
Q

What is characteristic in reptilian and amphibian retina.

A

The presence of conus papillaris arising from the optic disc.