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Ocular Biology 2 > Retinal Biochemistry > Flashcards

Retinal Biochemistry Flashcards

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1
Q

What are the 4 major functions of the retina?

A

Phototransduction, Light and Dark Adaptation, Separation of Signals, Initial info processor

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2
Q

This nuclei of the brain aids in visual perception

A

Lateral Geniculate Nucleus

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3
Q

This nuclei of the brain aids in pupillary reflex

A

Pretectal Area of Midbrain

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4
Q

This nuclei of the brain aids in eye movement

A

Superior colliculus

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5
Q

This nuclei of the brain aids in control of diurnal rhythms and hormonal changes

A

Suprachiasmatic Nucleus of the Hypothalamus

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6
Q

Mueller cells provide _____ and _____ support to the neurons of the sensory retina

A

Structural and Metabolic

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7
Q

Mueller cells regulate the extracellular space by _______ off potassium into the vitreous, blood and subretinal space.

A

Siphoning

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8
Q

Potassium is increased during _____ activity.

A

Neuronal

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9
Q

What are the functions of the RPE?

A
  • Synthesize Extracellular Materials
  • Phagocytosis of OS discs
  • Contain hydrolyzing enzymes to digest discs
  • Absorption of scattered light
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10
Q

What material is synthesized from the apical portion of RPE?

A

Proteoglycans

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11
Q

What material is synthesized from the basal portion of the RPE?

A

Bruch’s Membrane

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12
Q

What cell in the RPE absorbs scattered light not captured by the photoreceptors?

A

Melanosomes

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13
Q

By absorbing scattered light, the RPE protects the eye from ___ _____ damage.

A

free radical damage

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14
Q

The outer segment of photoreceptors are specialized for ____.

A

photoreception

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15
Q

How does the outer segment detect light?

A

A photon is absorbed by visual pigment molecules on the outer segment discs

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16
Q

How does the phototransduction cascade work?

A

Light is converted into an electrical signal, which changes the membrane potential

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17
Q

What are the 2 main proteins found in OS discs?

A

Peripherin and Rom-1

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18
Q

What is the function of Peripherin and Rom-1?

A

To regulate disc membrane fusion events in disc morphogenesis

19
Q

What is the main visual pigment protein found in OS discs to help detect light? this aids in what pathway?

A

Opsin, 80% of OS protein

Phototransduction

20
Q

What’s the significance of have polyunsaturated fatty acids in the rod OS?

A
  • aids in the fluidity of the disc membrane
21
Q

What’s the major fatty acid found in retinal rod OS?

A

DHA

22
Q

What are the 3 characteristics of photoreceptors

A

Post-mitotic
Terminally Differentiated
Undergo membrane renewal

23
Q

Why do membranes go through membrane renewal?

A

allows the PR to replace old or damaged outer segment discs

24
Q

In disc morphogenesis, discs are formbed by _______ of the ______ outer segment plasma membrane

A

evagination, basal

25
Q

Disc shedding occurs as a ____ process.

A

daily process

26
Q

In rods, onset of light in the morning triggers phagocytosis for how many hours?

A

1-2 hrs

27
Q

Human OS discs are replaced in how many days?

A

10

28
Q

Outer Segments of PR are susceptible to oxidative damage due to what 3 things?

A

High oxygen content, High concentration of PUFAs, Light stimulation (photooxidation)

29
Q

What are the 2 actions of free radicals

A

Membrane damage and Lipid Peroxidation

30
Q

How does Lipid Peroxidation work?

A

Free radicals attach to PUFAs and induce a chain rxn that breaks down membranes

31
Q

Name the 5 defense mechanisms to free radical damage.

A

Absorption of Light, filtration of light, Antioxidants, Enzymes, RPE,

32
Q

what 3 antioxidants can be used as a defense mechanism?

A

Beta-Carotene, Vitamin C and E

33
Q

What enzymes can be used as a defense mechanism against free radicals?

A

Superoxide dismutase
Glutathione peroxidase
Catalase

34
Q

What are the 2 xanthophylls used to help filter light? How?

A

Lutein and Zeaxanthin

Form an optical filter that helps filter damaging blue light

35
Q

Which xanthophyll filters the most blue light?

A

Lutein

36
Q

What cells help with the absorption of light?

A

melanosomes

37
Q

What 2 components make up the visual pigment?

A

Chromophore (11-cis-retinal) and Opsin

38
Q

What is the derivation and structure of Chromophore?

A

Vitamin A

Aldehyde

39
Q

The RPE acquires Vitamin A from what 3 areas?

A

Circulation
Ingested Discs
Any released during phototransduction

40
Q

What is the structure of Opsin?

A

Glycoprotein, an integral membrane protein

41
Q

How many alpha helices is found in opsin? Which one does chromophore attached to?

A

7 alpha helices, chromophore is attached to the 7th one

42
Q

Scotopsin is for which photoreceptor?

A

Rod

43
Q

Photopsin is for what photoreceptor?

A

Cone

Ocular Biology 2 (5 decks)

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