Cartilage Flashcards

1
Q

what is cartilage?

A
  • a semi rigid connective tissue
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2
Q

what is cartilage made up of?

A

chondrocytes and a vast gel-like extra-cellular martix

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3
Q

what does cartilage provide?

A

mechanical stability, strength, rigidity and some elasticity

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4
Q

what does cartilage resist?

A

compression

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5
Q

is cartilage vascular or avascular?

A

avascular

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6
Q

what are the 3 main types of cartilage?

A

hyaline, white fibrocartilage and elastic cartilage

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7
Q

what are chondrocytes?

A

the cellular component of cartilage- mature cartilage cells

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8
Q

chondrocytes occupy how much of total cartilage tissue?

A

1-10%

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9
Q

are chondrocytes metabolically active or inactive?

A

inactive- absence of vascular supply and innervation

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10
Q

what is a chondron?

A

functional unit composed of a chondrocyte and its pericellular covering

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11
Q

progression from mesenchymal stem cells go to what?

A

chondroblasts

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12
Q

chondroblasts mature and go to what?

A

chondrocytes

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13
Q

mesenchymal tissue is derived from what?

A

paraxial and lateral plate mesoderm, posterior to the primitive streak

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14
Q

undifferentiated mesenchymal cells do what?

A

migrate and undergo condensation

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15
Q

chondroprogenitors proliferate and do what?

A

differentiate to form chondroblasts

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16
Q

chondroblasts further differentiate and do what?

A

mature to form chondrocytes

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17
Q

chondrocytes undergo what?

A

a terminal differentiation and hypertrophy to become specialised to a specific type of cartilage; hyaline, fibrous or elastic

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18
Q

what is the development of chondrocytes called?

A

chondrogenesis

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19
Q

what are the stages in the development of chondrocytes?

A

condensation, proliferation and differentiation, differentiation and maturation, terminal differentiation

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20
Q

if chondrocytes continue to differentiate what occurs?

A

continue to differentiate tot chondrogenesis processes to endochondral ossification which only occurs at epiphyseal growth plates

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21
Q

what are some roles of chondrocytes?

A

important for both structure and function of cartilage

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22
Q

chondrocytes proliferate and secrete what?

A

components of the extracellular matric – collagen, glycoproteins, proteoglycans, hyauronan.

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23
Q

chondrocytes regulate what?

A

cartilage synthesis and cartilage degradation.

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24
Q

chondrocytes can produce what?

A

enzymes that degrade components of the extracellular matrix – collagenase, neutral proteinases, cathepsins.

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25
Q

chondrocytes have a dual function doing what?

A

where they can both regulate synthesis and degradation of cartilage.

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26
Q

potential damage to the extracellular matrix means what?

A

matrix is replaces and so cartilage is maintained

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27
Q

what is the superficial zone of chondrocytes?

A

collagen types II, IX, X, aggrecans, lubricin

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28
Q

what is the middle zone of chondrocytes?

A

collagen types II, IX and X, biglycan, decorin, greater amounts of aggrecans

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29
Q

what is the deep zone of chondrocytes?

A

collagen type X, biglycan, decorin, aggrecans, MMP13

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30
Q

how many types of collagen are present in vertebrates?

A

28

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31
Q

what kind of protein is collagen made from?

A

elastic proteins

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32
Q

what kind of resilience does collagen have?

A

90%, not permanently deformed

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33
Q

what do all collagen contain?

A

1 triple- helical domain

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34
Q

where is collagen present?

A

in the Extra cellular matrix

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35
Q

what does collagen provide in the ECM?

A

stability, shape, mechanical

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36
Q

type I collagen is found where?

A

bones, skin and tendons

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37
Q

type II collagen is found where?

A

main collagen of cartilage

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38
Q

type I collagen is present in what?

A

present in fibrocartilage

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39
Q

type II collagen is present in what?

A

in all cartilage

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40
Q

what cartilage is most abundant ?

A

type I

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41
Q

which is a thinner cartilage?

A

type II

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42
Q

what do type I and type II cartilage form?

A

fibrils

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43
Q

Glycoprotein chondronectin promotes what?

A

adherence of chondrocytes to the type II collagen matrix

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44
Q

what does the extracellular matrix in cartilage consist of?

A

ground substance & fibrous proteins

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45
Q

what kind of matrix is the extracellular in cartilage?

A

pericellular, terrirotrial interterritorial matrix

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46
Q

cartilage can resist what?

A

deformation through water absorption.

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47
Q

glycosaminoglycans become attached where?

A

to a core protein module which will then be attached and stabilised by a link protein to the hyaluronan strand.

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48
Q

major structural component in ECM in cartilage are what?

A

hyaluronan

link protein

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49
Q

hyaline cartilage makes up what?

A

the majority of cartilage in the body

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50
Q

what type of collagen is hyaline cartilage?

A

type II collagen

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51
Q

what is present in hyaline cartilage?

A

perichondrium

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52
Q

where is hyaline cartilage found?

A

present at articular surfaces

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53
Q

cartilage in ECM contains what?

A

70% water

25% organic material (60% type II collagen, 40% protein aggregates)

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54
Q

fibrocartilage contains what?

A

Type I collagen

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55
Q

what is the strongest cartilage?

A

fibrocartilage

56
Q

where is fibrocartilage found?

A

in soft tissue- to-bone attachments

57
Q

does fibrocartilage contain perichondrium?

A

no

58
Q

what percentage of collagen does the IV disc contain?

A

same quantities

59
Q

what type of fibrocartilage is in IV discs?

A

connecting fibrocartilage

60
Q

what type of fibrocartilage is in menisci?

A

intra articular fibrocartilage

61
Q

what type of fibrocartilage is in tendons of muscles?

A

stratiform fibrocartilage

62
Q

what type of fibrocartilage is in acetabular labrum?

A

circumferential fibrocartilage

63
Q

what is the only type II collagen?

A

elastic cartilage

64
Q

what does elastic cartilage contain?

A

elastic fibres in matrix

65
Q

does elastic cartilage contain perichondrium?

A

yes

66
Q

what does elastic cartilage allow?

A

for structures to maintain their shape and give flexibility

67
Q

where would you find elastic cartilage?

A

pinna of ear, epiglottis

68
Q

what is perichondrium?

A

connective tissue which usually surounds cartilage

69
Q

where is perichondrium derived from?

A

mesenchymal cells- flatten and elongate

70
Q

what are the 2 layers of perichondrium?

A

outer fibrous layer and inner chondrogenic layer

71
Q

what cells are derived from perichondrium?

A

osteoblasts and endothelial cells

72
Q

what is the function of perichondrium?

A

Regulates the initiation of vascular invasion

Vasculogenic/angiogenic programme

73
Q

Main function of the vertebral column cartilage is what?

A

is to resist compression due to loading.

74
Q

In articular cartilage and intervertebral disc collagen provides what?

A

the ability to resist compressive loading so protecting the cells from injury by mechanical trauma.

75
Q

Hyaline cartilage and fibrocartilage are present where?

A

Hyaline at articular surfaces

Fibrocartilage in the IV discs

76
Q

what are the 3 zones present in articular surfaces?

A

hTangential zone
Transitional zone
Deep zone

77
Q

what is the tangential zone in contact with?

A

with synovial fluid - resist a variety of forces

78
Q

how much does the tangential zone make up?

A

10-20% of total thickness

79
Q

how are collagen fibres arranged in the tangential zone?

A

tightly packed

80
Q

is there a high or low number of chondrocytes in the tangential zone?

A

high number

81
Q

how much does the transitional zone make up?

A

40%-60% total cartilage volume

82
Q

what does the transitional zone make up?

A

proteogylcans and collagen fibrils

83
Q

how is the organisation in the transitional zone?

A

collagen and chondrocyte organisation

84
Q

where is the 1st point for compression resistance?

A

transitional zone

85
Q

how much does the deep zone makeup?

A

30% of total cartilage volume

86
Q

what is the orientation of the deep zone?

A

collagen fibres arranged perpendicular to surface

87
Q

in the deep zone what is the content of proteoglycan and water?

A

high proteoglycan and low water content

88
Q

the deep zone has greatest resistance to what?

A

compression

89
Q

the annulus fibrosis is composed of what?

A

many layers of cartilage

90
Q

in relation to the annulus fibrosis where is type I collagen found?

A

at periphery

91
Q

in relation to the annulus fibrosis where is type II collagen found?

A

closer to the nucleus pulposus

92
Q

The presence of cartilage in the vertebral column is of importance for what?

A

Flexibility and movement of the spine
Support of body weight
Shock absorber

93
Q

The cartilaginous sites are where?

A

Zygapophyseal (facet) joint – hyaline cartilage
Intervertebral disc – fibrocartilage
Cartilagenous end plate – hyaline cartilage

94
Q

what kind of joint is the zygapophyseal joint?

A

synovial planar joint

95
Q

where is the zygapophyseal joint?

A

an articulation between superior and inferior articular processes of neighbouring vertebrae

96
Q

what is the function of a zygapophyseal joint?

A

Influences flexion and extension
Little effect on lateral flexion
Restricts axial rotation
Involved in load transmission through posterior elements – facet joint thought to transmit 3-25% of segmental load (increases in disease)

97
Q

The articular surfaces of a zygapophyseal facet joints are covered with what?

A

hyaline cartilage

98
Q

does the layer of cartilage of the zygapophyseal joint vary and where?

A

yes along the vertebral column

99
Q

is the thickness of hyaline cartilage consistent within each facet joint in relation to the zygapophyseal joint?

A

not consistent, The layer of cartilage becomes thicker towards the centre of the articular surface
Peak thickness level is approximately 1 mm

100
Q

There is some debate regarding the complete covering of the articular surfaces with hyaline cartilage [Jaumard et al. (2011)] what is this?

A

Some believe the extremities of the articular surfaces have bone exposed
One study found the level of exposed bone to be highest in the upper cervical region (3 times more than the lower cervical region)
There is less cartilage coverage in females – this claim is backed by the greater incidence of neck trauma in females

101
Q

what is the main function of hyaline cartilage present in the zygapophyseal joint is what?

A

to reduce friction during movement and to increase lubrication (along with the synovial fluid produced)

102
Q

what is another function of hyaline cartilage present in the zygapophyseal joint?

A

it plays some role in bearing compressive tensile forces and shear loads
This is due to the structural arrangement of the cartilage tissue
As well as the increased presence of proteoglycans in deeper zones which can absorb water and reduce compressibility of cartilage

103
Q

The extracellular matrix of cartilage tissue is a laminate structure with 3 zones which are?

A

superficial, middle and deep zones

104
Q

IV discs allow what?

A

allow for the indirect articulation of vertebral bodies.

105
Q

The articular surfaces of cartilaginous joints are connected by what?

A

entirely by cartilage,

106
Q

where are primary and secondary cartilaginous joints found?

A
Primary cartilaginous – epiphyseal growth plate
Secondary cartilaginous (symphysis) – intervertebral discs, pubic symphysis
107
Q

secondary cartilaginous joints do what?

A

hold vertebrae together

108
Q

how many IV discs are there?

A

23 (6C, 12T, 5L)

109
Q

what is the contradictory fact for the IV discs?

A

contradicted by Palastanga et al. (2012) who say 24 in total with possible additional discs between fused sacral segments

110
Q

discs increase or decrease in thickness down the vertebral column?

A

increase

111
Q

what is the exception of thickness in the discs?

A

slightly narrow in upper thoracic region

112
Q

what are the 3 distinct regions of the IV discs?

A

Central nucleus pulposus
Outer annulus fibrosis
Superior and inferior cartilagenous endplates

113
Q

what is the structure of the nucleus pulposus?

A

Random arrangement of collagen fibres
Radially organised elastin fibres
Hydrated extracellular matrix containing aggrecan

114
Q

what is the structure of the annulus fibrosus?

A

concentric layers od cartilage- lamellae, collagen type I and II fibres lying parallel within lamella- 60 degrees to the vertical axis
elastic fibres arranged between lamellae

115
Q

cell morphology of the annulus fibrosus?

A

outer region- fibroblast- like, thin, elongated, parallel to collagen fibres
inner region- more oval

116
Q

what are the IV specific features?

A

Cells possess cytoplasmic projections (30 micrometres or longer)
Reduced aggregation of aggrecan
Increased levels of glycosaminoglycans (keratan sulphate) instead of high levels of aggrecan

117
Q

function of the nucleus pulposus?

A

Shock absorber
Even distribution of pressure across the disc
Components of extracellular matrix keep disc hydrated

118
Q

function of annulus fibrosus?

A

Shock absorber
Tensile strength due to arrangement of collagen fibres
Lamina resists compressive forces
Disc able to return to original orientation due to elastin fibres
Anchorage of tissue to bone
Components of extracellular matric keep disc hydrated

119
Q

what is the vertebral end plate?

A

Thickened layer of cortical bone
Superior and inferior surface of vertebrae
Flattened surface to allow attachment to intervertebral discs

120
Q

what is the cartilagenous endplate?

A

Thin layer of hyaline cartilage
Between vertebral endplate and nucleus pulposus
Thickest on the outer edge
Thickness consistent along length of vertebral column - debate amongst literature about precise thickness (ranging from 0.1– 1.6 mm)

121
Q

what type of cartilage is in the cartilaginous end plates?

A

hyaline

122
Q

how are the collagen fibres arranged in the cartilaginous end plates?

A

arranged parallel to vertebral bodies and continue into intervertebral discs

123
Q

what kind of layers are in the cartilaginous end plates?

A

calcified and uncalcified

124
Q

are the cartilaginous end plates more hydrated or less hydrated than the nucleus pulposus and annulus fibrosus?

A

less hydrated

125
Q

what kind of canals are in the cartilaginous end plates?

A

vascular canals

126
Q

function of cartilaginous end plates?

A
  • mechancial barrier
  • support to neighbouring IV discs
  • even distribution of load across intervertebral discs
  • Anchors collagen fibres from in the intervertebral disc
  • semi-permeable allows diffusion of nutrients from blood vessels to the discs
127
Q

what is spondylosis?

A

Degenerative disease of the intervertebral discs resulting in stiff joints
Age-related wear and tear of the facet joint

128
Q

spondylosis occurs with what?

A

Cartilage degeneration occurs with increased age
Chondrocyte hypertrophy and dysfunction – not yet known how chondrocytes are activated in a way to cause disease
Cartilage repair mechanisms are believed to play a part
Increased proteolytic enzymes degrading extracellular matrix and reducing hydration – secondary synovitis results and increased joint stiffness

129
Q

what is the management for spondylosis?

A
No drugs to reverse process
Symptomatic management
Physiotherapy
NSAIDs
Surgery
130
Q

what is Intervertebral Osteochondrosis ?

A

disc degeneration
Back pain caused by normal progression of changes occuring in the intervertebral disc with age
Dysfunction of end plates responsible for disc degeneration – agreement across literature

131
Q

what are the Pathological changes of Intervertebral Osteochondrosis?

A

Nucleus pulposus becomes more fibrotic and less organised with increased age
Annulus fibrosus becomes disorganised – irregular lamellae
Formation of clefts and fissures in the discs
Ectopic calcification occludes vascular canals which disrupts nutrient transport to disc – study 4 demonstrates the link between occluded vascular canals, degenerated discs and ageing, from histological samples
Decreased glycosaminoglycans

132
Q

diagnosis for Intervertebral Osteochondrosis?

A

MRI

133
Q

management for Intervertebral Osteochondrosis ?

A

Physiotherapy
NSAIDs
Steroid injections
Surgery

134
Q

complications of Intervertebral Osteochondrosis ?

A

Sciatica
Disc herniation
Disc prolapse

135
Q

what is Uncovertebral Arthrosis?

A

Uncinate process of the vertebrae is a hooked projection on the superior surface of the vertebral body
Uncovertebral arthrosis is osteoarthritis specific to this joint – considered to be a complication of cervical osteoarthritis (not a lot of literature on this topic)

136
Q

where is Uncovertebral Arthrosis usually found?

A

Found in the cervical region of the vertebral column

137
Q

what is Uncovertebral Arthrosis more commonly known as ?

A

Luschka’s joint