ECM Flashcards

1
Q

What is ECM

A

Acellular component of present in all tissues and organs

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2
Q

list the 2 main types of ECM

A

Interstitial connective tissue matrix

Basement membrane

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3
Q

What are the components of ECM

A

Fibres: elastin + collagen

Ground substance: Glycosaminoglycans + Proteoglycans + Glycoproteins

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4
Q

List places where ECM is found

A
Bone
Cartilage
tendons 
blood vessel walls
subcutaneous fat
basemen membrane
dermal layer of skin 
cornea
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5
Q

Describe what collagen is and its structure

A

a large, insoluble, fibrous protein

made up of 3 collagen polypeptides which form a triple helix structure

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6
Q

What assembles collagen molecules into its strong helical structure?

A

presence of Gly(cine)-X-Y repeat motif

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7
Q

what are the two types of collagen, what cartilage are they present in and what functional property do they have

A

Fibrillar: found in type 1 and 2, provides strength. Found in skin, tendon, bone

Sheet/network forming: found in type 4, provide support and filter. Found in basement membrane.

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8
Q

Where is type 1 collagen found?

A

bone, tendon, skin (dermis), ligaments

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9
Q

Where is type 2 collagen found?

A

Hyaline cartilage

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10
Q

Where is type 3 collagen found?

A

granulation tissue, liver, bone marrow, lymphoid organs

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11
Q

Where is type 4 collagen found?

A

basement membrane

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12
Q

Where is type 5 collagen found?

A

linker to Basement membrane, in cornea

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13
Q

describe elastin, how is it arranged and what property does it have?

A

elastin is a structural protein arranged as fibres.

It is found in tissues which need stretch and recoil properties

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14
Q

What is needed to assemble elastin?

A

A structural glycoprotein called Fibrillin

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15
Q

What organs in elastin found in?

A

Lungs, skin, blood vessels, bladder

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16
Q

what is ground substance?

A

An amorphous (shapeless), colour, gelatinous material. It is found in the space between cells and fibres.

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17
Q

What forms a proteoglycan

A

A core protein and many GAGs

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18
Q

what does ground substance consist mainly of?

A

water

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19
Q

what is another name for GAGs

A

mucopolysaccharides

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20
Q

list the four different types of GAG and where they are found

A

hyaluronic acid - found in synovial fluid
keratAn sulphate - found in cartilage
HeparAn sulphate - found in basement membrane
chondroitin sulphate - found in cartilage

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21
Q

what properties do GAGs have?

A

They are hydrophilic so absorb water.
They provide cushioning and have hydrating properties.
They enabled ECM to withstand high compressive forces.

22
Q

what are proteoglycans also known as?

A

mucoproteins

23
Q

proteoglycans are mostly what?

A

carbohydrates (90-95%)

24
Q

list 4 types of Proteoglycans

A

Aggrecan
perlecan
Syndecan
Decorin

25
Q

where is aggrecan found and what type of GAG is present?

A

In cartilage

Chondrotiin sulphate + KERATAn sulphate

26
Q

where is perlecan found and what type of GAG is present?

A

in basement membrane

HepAran sulphate

27
Q

where is syndecan found and what type of GAG is present?

A

in cartilage

Chondroitin sulphate + heparan sulphate

28
Q

where is decorin found and what type of GAG is present?

A

widespread in connective tissues

Chondrotiin sulphate
Dermatan sulphate

29
Q

list 5 glycoproteins

A
fibrillin
fibronectin
entactin 
tenascin
laminin
30
Q

what is the role of fibronectin?

A

found in basement membrane

attaches to integrins and creates a provisional matrix for keratinocytes to move along to close the wound

31
Q

what makes the protein/fibres in the ECM?

A

Fibroblasts

32
Q

what is collagen synthesised as, what post translational modification does it undergo and what is the protein assembly?

A

Procollagen

Glycosylation + hydroxylation

Triple helix

33
Q

what is elastin synthesised as, what post translational modification does it undergo and what is the protein assembly?

A

tropoelastin

hydroxylation

fibrillin scaffold
cross linked fibres

34
Q

how are proteoglycans synthesised?

A

core protein is made on rER
Addition of carbohydrates in Golgi apparatus
delivered to extracellular component by exocytosis
assembled with other ECM components by fibroblasts

35
Q

If the ECM is never static what may it be undergoing?

A

Deposition
Degradation
Modification

36
Q

how is ECM degraded when it is remodelled? wen may it need to be degraded for remodelling?

A

Broken down by proteases, MMPs, and elastase

Used for wound repair, embryogenesis and angiogenesis

37
Q

how do pathogens degrade ECM? give an example pathogen

A

pathogens secrete collagenase which enables them to invade the host.

e.g. bacillus cereus

38
Q

what are matrix metalloproteinases?

A

enzymes which break down proteins found in the ECM and need calcium and zinc to function

39
Q

what is the basement membrane

A

a thin tough sheet of ECM

40
Q

What are components of the busmen membrane ?

A
Collagen type 4
perlecan (PG)
laminin (GP)
entactin (gp)
fibronectin (gp)
41
Q

what are the 3 layers of the ECM?

A

Lamina lucida
Lamina densa
Lamina fibroreticularis

42
Q

list some BM disorders

A

cancer
epidermolysis bullosa
goodpasture syndrome
Diabetes mellitus

43
Q

Describe goodpastures syndrome

A

autoantibodies fo collagen type 4 destroy the BM in glomerulus and lung.

44
Q

What is osteoid, how is it made and degraded?

A

ECM in bone. It forms the organic, unmineralised portion of bone matrix

It is made by osteoblasts and degraded by osteoclasts

45
Q

what is the eCM in joints?

A

cartilage

46
Q

what is the ECM in joints (cartilage) composed of ?

A
collagen type 2
aggrecan
chondroitin sulphate
Keratan sulpahte 
hyaluronic acid
47
Q

give an example of a disease when elastin in ECM is damaged

A

Supravalvular Aortic Stenosis

48
Q

give an example of a disease when Fibrillin-1 in ECM is damaged

A

Marfan Syndrome: skeletal, ocular & cardiovascular abnormalities

49
Q

give an example of a disease when collagen in ECM is damaged

A

Ehlers-Danlos Syndrome: joint & skin abnormalities e.g. hypermobility, stretchy skin

50
Q

give an example of a disease when keratin sulphate in ECM is damaged

A

Macular corneal dystrophy: corneal transparency

51
Q

give an example of a disease when perlecan in ECM is damaged

A

Dyssegmental dysplasia Silverman-Handmaker : severe form of neonatal lethal dwarfism