Exam 3 Koh- Vitreous Biochem Flashcards Preview

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Flashcards in Exam 3 Koh- Vitreous Biochem Deck (46)
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1

Vitreous is a highly hydrated gel-like _____ _____

Extracellular matrix

2

What is the vitreous made of?

99% water, gel like, virtually acellular apart from a few cells (hyalocytes) in the periphery

3

What does viteous regulate?

Eye growth and shape during development, a barrier to the cellular invasion/migration (transparency), lowers oxygen tensions

4

Vitreous degneration are central to ______ pathologies

Retinal

5

Asteroid hyalosis

A degenerative condition of the eye involving small white opacities in the vitreous humor

6

Synchysis scintillans

Resulting in liquefied vitreous humor and the accumulation of cholesterol crystals within the vitreous

7

What is the biochemical composition of the vitreous?

The main fibrillar proteins are collagen fibrils, the major GAG is is hyaluronan (HA), endows the tissue with shape, strength, flexibility, and resistance to tractional forces

8

Low-level postnatal _____ _____ does occur in vitreous

Collagen synthesis

9

How much collagen synthesis occurs in bovine eyes

About 60 mg/ml

10

How much collagen synthesis occurs in human eyes?

About 300 mg/ml

11

The concentration of collagen ______ as the eye grows

Decreases

12

What types of collagen in the vitreous?

2, 9, 5/11

13

Collagens can assemble into what types of structures?

Triple-helical structure (gly-X-Y), proline and hydroxyproline, lysine and hydroxylysine

14

What is collagen type 2 in the vitreous?

A fibril-forming collagen that accounts for 60-75% of the collagen in vitreous

15

What is Stickler's syndrome?

Premature vitreous degeneration and NSC

16

What is type 9 collagen in the vitreous?

Has a multiple-domain structure, up to 25%, synthesized in proteoglycan form having a single chondroitin sulphate

17

Type 5/11 collagen co-assembles with type ____ to form the core

2

18

How much type 5/11 collagen is in the vitreous?

10-25%

19

What is a ubiquitous component of extracellular matrices?

Type 6 collagen

20

What does type 6 collagen do?

Binds fibrillar collagens and HA, linking together the heterotypic collagen fibrils and HA

21

Marfan's syndrome is caused by mutations in _______

Fibrillin-1

22

Opticin binds what 2 things?

Growth hormone and GAGs

23

What is hyaluronan?

HA is the predominant GAG in mammalian vitreous, not covalently linked to a core protein

24

What is versican?

A large proteoglycan with a central domain that carries multiple CS chains

25

Mutation in ______ causes Wagner's syndrome

Versican

26

What is Wagner's syndrome?

Pre-retinal membranes and chorioretinal atrophy

27

The vitreous has how much more ascorbate than plasma?

10x (0.46 to 0.04)

28

What forms the bulk of the vitreous body?

Central vitreous

29

Collagen fibrils course in an ______ direction

Anterior-posterior

30

The lowest amount of collagen is within the _____ vitreous

Central