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Anatomy and Physio Final > RPE > Flashcards

Flashcards in RPE Deck (79):
1

How is the RPE and photoreceptor outer segment aligned?

apex to apex

2

What is in the neural retina?

photoreceptors, bipolar, ganglion, horizontal and amacrine cells

3

Where is the ocular ventricle?

The potential space between the RPE and POS

4

After lens induction begins, the _____ _____ collapses back onto itself. The inner invagination becomes the _______ while the outer part becomes the _______

After lens induction begins, the *optic vesicle* collapses back onto itself. The inner invagination becomes the *neural retina* while the outer part becomes the *RPE*

5

The basement membrane of the RPE becomes ____ ____ during development. The basement of the neural retina becomes the ____ ____ ____

The basement membrane of the RPE becomes *Bruch's membrane* during development. The basement of the neural retina becomes the *inner limiting membrane*

6

Where would you find microvilli on the RPE?

the apical portion. Microvilli envelope the photoreceptors

7

The epithelial cells of the Blood Retinal barrier are bound together by _____ _____ and divide the cells into apical halves that face the _______ and basal halves that face the ______

The epithelial cells of the Blood Retinal barrier are bound together by *tight junctions* and divide the cells into apical halves that face the *receptors* and basal halves that face the *choroid*

8

What gives the RPE its black appearance?

Pigment granules

9

What is proliferative vitreoretinopathy?

Pigment granules separate from the RPE as free cells and appear as "tobacco dust" in the vitreous. Cells then settle and form contractile fibrocellular membranes

10

What part of the retina uses the most energy?

The outer segments

11

Photoreceptor survival depends on having _____ and _____ in large quantities

blood and glucose

12

What are the four extreme properties that the choroid has developed to meet the demands of the photoreceptors?

1. High permeability
2. High throughput of blood - more blood faster
3. High oxygen levels
4. No auto-regulation

13

Name the two problems created by the thin and sparse central retinal circulation (made necessary since it lies in the path of light)

1. Very little oxygen reserve
2. Small vessel diameter

14

What are the five functions of the RPE? (RPEAM)

Retinal barrier
Photoreceptor renewal and light absorption
Environment protection against superoxides
A... Vitamin A metabolism and storage
Matrix synthesis

15

What are the two aspects of the blood-retinal barrier?

1. Tight junctions of the endothelial cells of the CRC
2. Tight junctions of the RPE keeping blood out of the retina

16

The fenestrated choriocapillaries permit leakage of _______

protein

17

Protein concentration in front of the RPE is ____ while the concentration in the ECS behind the RPE is ____

Protein concentration in front of the RPE is *low* while the concentration in the ECS behind the RPE is *high*

18

The RPE can absorb up to ___% of the aqueous secretion in a day

50%

19

What are the factors preventing RPE/retina detachment?

1. Oncotic fluid gradient
2. Finger-like folds of the RPE
3. Interphotoreceptor matrix

20

Due to the high membrane fluidity required by the retina, the ____ bonds of the _____ _____ _____ make the retina highly susceptible to superoxide attack.

Due to the high membrane fluidity required by the retina, the *double* bonds of the *unsaturated fatty acids* make the retina highly susceptible to superoxide attack.

21

Hurler's syndrome is the buildup of _____ molecules due to an improperly functioning degrading _____

Hurler's syndrome is the buildup of *GAG* molecules due to an improperly functioning degrading *enzyme*

22

Photoreceptors are degraded by _____ and ____

Photoreceptors are degraded by *phagocytosis* and *autophagy*

23

A single RPE cells is responsible for phagocytosing ____ or more rods

10

24

Define autophagy

Self-digestion by a cell through the action of enzymes of the same cell

25

What are the two patterns of photoreceptor replacement?

1. Membrane replacement
2. Molecular replacement

26

All structures in the rod turnover during membrane replacement except for ____

DNA

27

What two molecules are replaced independent of the discs in rods?

transducin and PDE

28

Where would the disc accumulate if photoreceptor renewal did not take place?

subretinal space

29

Phagocytosis of the photoreceptor outer segment is carried out by the ____

RPE

30

In order to digest the outer segment portion of a photoreceptor, a _____ fuses with the ____ ____.

In order to digest the outer segment portion of a photoreceptor, a *lysosome* fuses with the *RPE phagosome*

31

In embryogenesis up till 6 months, growth of photoreceptors is ______ than phagocytosis. From Age 6 months until adulthood, growth is ______ to phagocytosis. Disease is observed when growth is ______ than phagocytosis.

In embryogenesis up till 6 months, growth of photoreceptors is *greater* than phagocytosis. From Age 6 months until adulthood, growth is *equal* to phagocytosis. Disease is observed when growth is *less* than phagocytosis.

32

What can radioautography do?

Allows the researcher to follow the synthesis of a molecule by administrating a "pulse" of radiolabeled molecule into the molecule.

33

A radiolabeled molecule is referred to as ____

"hot"

34

An unlabeled molecule seen during radioautography is referred to as _____

"cold"

35

Photoreceptor renewal is _______ in cones than in rods

Slower

36

What do the proteins incisin and peripherin do in photoreceptors?

control the spacing of the discs

37

Where are polysaccharides found in a photoreceptor?

Between the discs. Acts as a cushion

38

The label in radioautography is found in a lipid-surrounded vesicle known as a _______

Schleppersome

39

Rods are phagocytosed 1.5 hours after _____ and the cones are phaocytosed 1.5 hours after _____

Rods are phagocytosed 1.5 hours after *dawn* and the cones are phaocytosed 1.5 hours after *nightfall*

40

The circadian rhythm runs on a ___ hour cycle

12

41

True / False. Seeing and circadian control rely on the same receptor

Fuck no

42

Constant light results in the ______ of the outer segments while constant darkness results in _____ of the outer segments

Constant light results in the *shortening* of the outer segments while constant darkness results in *elongation* of the outer segments

43

What two methods has the cornea developed to act again oxidation by superoxides?

Chemical mechanism - superoxide dismutase
Anatomical mechanism - replacement of tissue

44

Oxidation takes place across what type of bond?

double bonds

45

Why can't the lens replace its own tissue?

Cells are sloughed off towards the center

46

Shorter wavelength light is ______ destructive than longer wavelength light

more

47

Why is the retina the weakest tissue of the body?

Retina has highly fluid membranes

48

Macular pigments surround the macula and absorb _____ light in order to fight off free radicals.

blue light

49

The lens protects the retina by absorbing most of the incoming _____ light

UV light

50

Superoxides can be broken down to hydrogen peroxide and oxygen in the presence of ____, ____, ___, and _____ ______

Zn, Cu, Mn, and superoxide dismutase

51

Hydrogen peroxide may revert back to superoxide in the presence of ____

Fe ions

52

The Glutathione peroxidase pathway (the predominant retinal pathway) requires ____

Se++

53

As lipids become crosslinked, the super destructive element ________ is kicked out

malonaldehyde

54

Vitamins __ and __ are used to get rid of malonaldehyde

Vitamins C and E

55

When lipofuscin accumulates in the RPE, it becomes _____

Drusen

56

Early accumulation of lipfuscin is seen in _____ and _____

Stargardt's and ARMD

57

Each RPE cell ingests more than any other phagocytic cell at __% of its own volume

7%

58

11-cis-retinal + aporhodopsin -> ____ + _____

Rhodopsin + water

59

When exposed to light, rhodopsin breaks down into ______ + ______

aporhodopsin + all-trans-retinal

60

Humans typically begin with _______ photoreceptors

100,000,000

61

Retinal detachment = starvation due to a lack of ____ and ____

oxygen and glucose

62

______ _____ is the basement membrane of the RPE

Bruch's membrane

63

What happens when Bruch's membrane is stretched?

neovascularization

64

Fatty acid deficiency in the choroid results in the inability to delivery ____ _ to the retina. This may lead to ____ ____

Vitamin A. Night blindness

65

_____ ____ is a generice name for a group of inherited disorders that cause progressive loss of photoreceptor and RPE function

Retinitis Pigmentosa (RP)

66

RP prevalence is about

1:4,000

67

Damage to the ___ is predominant in RP

rods

68

In the oxygen toxicity hypothesis: as the outer segments are lost, oxygen use by the ____ diminishes and the ___ ___ is flooded with oxygen.

In the oxygen toxicity hypothesis: as the outer segments are lost, oxygen use by the *photoreceptors* diminishes and the *outer retina* is flooded with oxygen.

69

photoreceptors that survive oxygen toxicity are damaged and upregulate expression of _____ _____ which slows degeneration

protective factors

70

What are the two types of ARMD?

dry and wet

71

In Dry ARMD, drusen appears which can either be ____, ____, or _____

soft (acute), hard (chronic), or calcified (under repair)

72

Why does drusen accumulate in the macula more than the fovea?

the fovea is protected by pigment

73

Accumulation of Drusen can lead to

retinal detachment

74

How does Wet ARMD differ from Dry ARMD?

neovascularization in Wet ARMD

75

Aging changes may cause _____ blood flow

decreased

76

What transport mechanisms are used to pump ions in and out of the RPE?

Na/K
Na/K/Cl co-transport
Na/2HCO3 co-transport
Na/H2O:Lac

77

Most potassium in the retina exist through the ____ ____

retinal membrane

78

HCO exits the retina through the ____ _____ in the RPE choroidal membrane

Cl/HCO3 exhangers

79

The retinal barrier creates a retina ____ transepithelial potential as a result of transepithelial transport of ion

The retinal barrier creates a retina *positive* transepithelial potential as a result of transepithelial transport of ion