Cartilage and Bone Flashcards Preview

Z OLD Tissues of the Body > Cartilage and Bone > Flashcards

Flashcards in Cartilage and Bone Deck (167):
1

Is cartilage a vascular or avascular tissue?

Vascular

2

What does cartilage consist of?

An extensive cellular matrix in which lies chondrocytes

3

What is the space for each chondrocyte called?

Lacuna

4

What is the role of chondrocytes?

Produce and maintain the extracellular matrix

5

What does the large ratio of GAGs to type II collagen in the cartilage matrix permit?

Ready diffusion of substances between chondrocytes and the blood vessels surrounding the cartilage

6

How could the extracellular matrix of cartilage be described?

Solid and firm, but also rather pliable

7

What is the advantage of the cartilage matrix being pliable?

It makes it resilient to repeated application of pressure, and so allows cartilage to act as shock absorbance

8

What is there a large amount of in the extracellular matrix?

Hyalyronic acid

9

What is the purpose of the hyaluronic acid in the extracellular matrix?

It assists the resilience to repeated application of pressure

10

What are the 3 types of cartilage?

#NAME?

11

What does hyaline cartilage matrix contain?

Proteoglycans, hyaluronic acid and type II collagen

12

What are the hyaluronic proteoglycan aggregates bound to in hyaline cartilage?

Fine collagen matrix fibres

13

What is the matrix of elastic cartilage like?

Like that of hyaline cartilage, but with addition of many elastic fibres and elastic lamellae

14

What does fibrocartilage have it its matrix?

Abundant type I collagen fibres, in addition to matrix material of hyaline cartilage

15

What is the cell type in hyaline cartilage?

Chondrocytes

No other cell type present

16

How are chondrocytes present in hyaline cartilage?

Singly, or, if recently divided, in small clusters called isogenous groups

17

What happens to chondrocytes within the isogenous groups?

They separate as they elaborate extracellular matrix

18

Why is hyaline cartilage important in early fetal development?

It is the precursor model of those bones which develop by endochondral ossification

19

What happens as long bones develop?

Some hyaline cartilage remains at the articulating surface, and at epiphyseal growth plate until growth ceases

20

Where is hyaline cartilage seated?

#NAME?

21

What covers the margin of hyaline cartilage?

Perichondrium

22

What does perichondrium contain?

Many elongated, fibroblast-like cells

23

What can happen to the fibroblast like cells in perichondrium?

They can develop into chondroblasts, and thereafter chrondrocytes

24

Where do chrondrocytes lie?

In cartilage extracellular matrix

25

What is the function of chondrocytes in the extracellular matrix?

They produce and maintain the matrix

26

What type of tissue is perichondrium?

A dense connective tissue

27

What do the fibroblast-like cells of the perichondrium give rise to?

Flat, newly formed chondroblasts

28

What do chondroblasts secrete?

Matrix components

29

What eventually happens to chondroblasts?

They round up to develop chondrocytes

30

What is the result of the formation of chondrocytes from chondroblasts?

The formation of cartilage

31

What is the cartilaginous growth from the periphery known as?

Appositional growth

32

What may happen to chondrocytes deeper in the cartilage?

They may divide and give rise to isogenous groups by mitosis

33

What is the result of deposition of further matrix by the isogenous groups formed deeper in the matrix?

Interstital growth

34

What happens to the cells of isogenous groups as they lay down further matrix?

They separate

35

How can you tell when chondrocytes have recently divided?

They are close together

36

What features of cartilage permit resilience to varying pressure levels?

#NAME?

37

Why does territoral matrix tend to stain darker with H&E stain than interterritoral matrix?

It is more highly sulphated

38

What directs the synthetic activity of chondrocytes?

Pressure loads applied lead to the cartilage creating mechanical, electrical and chemical signals

39

What is the precursor of most bones?

A hyaline cartilage model or template

40

What happens to the hyaline cartilage model for bones?

It’s mineralised to form bone

41

What happens to the hyaline cartilage of developing tarsal bones?

It will ossify

42

What is not present at articulating surfaces?

Perichondrium

43

Where is perichondrium found?

At non-articulating surfaces and contributing to developing joint capsule

44

How is hyaline cartilage positioned at the end of a long bone that hasn’t finished developing?

It lines the articulating surface of the bone, and forms the epiphyseal growth plates

45

What is the epiphysis?

The head of bone

46

What is found at the epiphysis?

Spongy/cancellous bone, with compact bone at sides

47

What does the growth plate separate?

The epiphysis and metaphysis

48

What is the metaphysis?

The wide region between the epiphysis and diaphysis

49

What is the diaphysis?

The shaft of the bone

50

Where do the chondrocytes of the cartilage at the epiphyseal edge of long bones lie?

In lacuna

51

Is the articular surface of bone smooth or rough?

Smooth

52

What is the advantage of the articular surface of bone being very smooth?

Provides relatively friction free articulation

53

What is the articular surface of long bone composed of?

Hyaline cartilage without perichondrium

54

What is the advantage of the irregular boundary between articular cartilage and underlying bone?

There’s less likelihood of one sliding of the other

55

Do elastic fibres calcify with ageing?

No, unlike hyaline

56

Where is elastic cartilage found?

- Pinna of ear
- External acoustic meatus 
- Epiglottis 
- Eustachian tube

57

What are the layers of the pinna of the ear?

- Muscle 
- Adipose tissue
- Fibrocollagenous tissue
- Elastic cartilage
- More fibrocollagenous tissue 
- Dermis
- Epidermis

58

How do elastic fibres lying in the extracellular matrix stain?

Darkly

59

What are the cell types in fibrocartilage?

Chondrocytes and fibroblasts

60

What is fibrocartilage a combination of?

Dense regular connective tissue and hyaline cartilage

61

How are cells often seen to be distributed in fibrocartilage?

In rows

62

Does fibrocartilage have surrounding perichondrium?

No

63

What kind of locations does fibrocartilage tend to be present?

Places where huge amounts of pressure can be applied

64

Give 4 locations fibrocartilage is found

- Sternoclavicular joint
- Temperomandibular joint 
- Menisci of knee 
- Pubic symphysis

65

What is the advantage of the resilience of fibrocartilage?

It can act as a shock absorber and resist shearing forces

66

How are chondrocytes arranged in fibrocartilage?

In rows or as isogenous groups

67

How many elongated fibroblast nuclei are evident?

Relatively few

68

What are entheses?

Points of attachment between tendons and bones

69

What is present at some entheses?

Fibrocartilage

70

What happens at the head of some bones?

Cancellous bone forms a network of fine body columns or plates

71

What is the advantage of the cancellous bone at the head?

Combines strength with lightness

72

What fills the spaces in cancellous bone?

Bone marrow

73

What does compact bone form?

The external surfaces of bones

74

How much of the bodies skeletal mass is compact bone?

~80%

75

What is the shaft of a long bone made up of?

- Endosteum 
- Periosteum

76

What is endosteum?

Inner surface

77

What is periosteum?

The outer surface

78

What is next to the endosteum in the shaft of bones?

Inner circumferential lamellae

79

What are inner circumferential lamellae?

Layers of bone that run right round the shaft of the bone

80

What runs in parallel with the direction of the bone?

The lamellae of the bone

81

What forms osteons?

Different layers of lamellae forming concentric circles around the osteonal artery

82

What canals does a bone section have?

- Haversian canals
- Volksmann’s canals

83

How does the arrangement of osteocytes differ between mature and immature bone?

#NAME?

84

What type of bone has reabsorption canals?

Mature

85

In what direction do reabsorption canals run?

Parallel with the osteons long axes

86

How is bone remodelled using resorption canals?

By boring a hole then laying down new osteon

87

What is found when bone has been remodelled?

Interstital lamallae

88

What are interstitial lamallae?

Bits of lamallae that seem to have belonged to complete circular system, but superseded by new osteon

89

What are the spaces where osteocyte lies in bone called?

The osteocyte lacunae

90

What is at the centre of each osteon?

A Haversian canal

91

In what direction do Haversian canals run?

Longitudinally along the bone

92

What cross connects between Haversian canals?

Volkmanns canal

93

What does each Haversian canal have around?

A system of lamallae around it

94

What does the Volksmann canals go through?

Lamallae belonging to adjacent osteons

95

What do Haversian and Volkmann canals carry?

Blood and lymph vessels, and nerves

96

What does an osteon consist of?

A Haversian canal and it’s concentric lamallae

97

What can happen when attempting to section bone?

Damage to microtone blades

98

What is normally done to make bone easier to section?

Decalcified

99

What is the problem with decalcifying bone to section?

The agents that do it damage the Haversian canal

100

How can the problem of the Haversian canals being damaged by decalcification agents be overcome?

By grinding the bone down to a very thin layer to look at

101

What happens to osteons as bone develops?

Resorption canals are bored down by osteoclasts, and then new lamallae are laid down by osteocytes, but bone remodelling doesn’t always follow exact course of preceding osteoclasts

102

Are osteons longitudinal or latitudinal?

Roughly longitudinal

103

What do osteons have the ability to as they go down bone?

Branch and terminate

104

What do osteocytes posses?

Canaliculi

105

What are canaliculi?

Tiny interconnecting tunnels

106

Where are tiny protoplasmic threads found in bone?

In the osteocytes entombed in lacunae between bony lamallae

107

What are protoplasmic threads?

Tiny cytoplasmic process

108

What do the osteocytes protoplasmic threads do?

Reach out to adjacent osteocytes via canaliculi

109

How to protoplasmic threads connect?

Via gap junctions

110

What is the purpose of the connections of protoplasmic threads?

Allow nutrients to be passed between osteocytes

111

What are canaliculi believed to connect with?

The central Haversian canal

112

What is the internal histological structure of trabeculae similar to?

That of compact bone

113

What is the difference between spongy bone and compact bone?

Spongy bone doesn’t have Haversian or Volksmann canals

114

Why doesn’t spongy bone have canals?

It seems it can get its nutrient form bone arrow, so doesn’t need blood vessels

115

What does each trabeculum consist of?

Numerous osteocytes embedded within irregular lamallae of bone

116

What is on the surfaces of trabeculae?

Osteoblasts and osteoclasts

117

What do osteoblasts do?

Build up bone

118

What do osteoclasts do?

Eat away

119

What do the cavities of trabeculae have around them?

Central lamallae

120

What are in the trabeculae cavities?

Adipose and haemopoietic cells

121

In do you have in growing bone spicles?

Osteoblasts depositing new osteon

122

What happens to the osteoblasts once they have deposited new bone?

They are now surrounded by new osteoid, and so are now osteocytes

123

What results from osteoclasts reabsorbing bone in spicules?

A depression in bone where they have eaten away

124

What is boring the tunnel through bone in remodelling?

A cutting cone

125

How to osteoclasts remove bone?

By releasing H + and lysosomal enzymes

126

Where do osteoblasts lay down new concentric lamallae?

On sides of boring tunnel

127

What is the composition of bone?

- 65% mineral (calcium hydroxyapatite crystals)
- 23% type I collagen 
- 10% water
- 2% non-collagen proteins

128

Why does bone resist fracture?

Because it has great tensile and compressive strength, and also a degree of flexibility

129

What is thought to be able to happen before excessive load causes fracture?

The lamallae can slip relative to one another

130

What results between broken bone ends when it breaks?

Haemotoma

131

What results in the haemotoma when bone breaks?

Bleeding from multiple blood vessels

132

What are the 4 stages in fracture repair?

- Haemotoma formation
- Fibrocartilaginous callous formation  
- Bony callus formation
- Bone remodelling

133

What leads to haemotoma formation in broken bone?

Blood vessels in bone and periosteum break

134

What is a haemotoma?

A mass of clotted blood

135

What happens to the bone cells at the fracture edge?

They die

136

Why do bone cells at the fracture edge die?

Because they have no blood supply

137

What happens as a result of the haemotoma?

Swelling and inflammation

138

What tissue needs to be removed when the bone breaks?

Dead/damaged tissue

139

What removes the dead/damaged tissue when the bone breaks?

Phagocytic cells and osteoclasts

140

What eventually happens to the haemotoma formed when bone breaks?

It’s removed by macrophages

141

How is a fibrocartilaginous callus formed?

- New blood vessels infiltrate the fracture haemotoma 
- A procallus (soft callus) of granulation tissue develops 
- Fibroblasts produce collagen fibres that span the break. Others differentiate into chrondroblasts, which give rise to a sleeve of hyaline cartilage 
- An externally bulging, fibrocartilaginous matrix therefore splints the bone

142

What is granulation tissue rich in?

Capillaries and fibroblasts

143

What is happening concurrently to the formation of a fibrocartilaginous callus?

Osteoblasts of nearby periosteum and endosteum, and multipotent cells from the bone marrow invade the fracture site, and being bone formation by forming spongy bone

144

What begins to appear within a week of the formation of the fibrocartilaginous callus?

New trabecular within the callus

145

How to the trabeculae in the callus develop?

As former fibrocartilaginous callus is converted to hard callus of cancellous bone

146

What ultimately happens to the fibrocartilaginous callus?

Endochondrial ossification replaces it all with cancellous bone

147

What is the role of intramembranous ossification in bone healing?

It produces new cancellous bone in the area

148

How soon do the processes that form a bony callus occur in a young person?

2 days after fracture

149

How long does bony callus formation continue for?

~2 months

150

What needs to happen as soon as the callus of spongy, cancellous bone is formed?

It needs to be remodelled into compact bone

151

Where is the remodelling into compact bone especially important?

In the cortical region

152

What is the cortical region?

The region of the former bone shaft

153

How long does the bone remodelling process happen for after a bone fracture?

Several months

154

What material is removed in bone remodelling?

The material bulging from the outside of the bone, and inwards into the medullary cavity

155

How is the bone for remodelling removed?

Osteoclasts

156

What is the final shape of the remodelled area of bone?

Same as that of original unbroken bone

157

Why is the final shape of remodelled bone the same as that of the original bone?

It responds to the same set of mechanical stressors

158

What can sometimes happen to fragments of bone in fractures?

It can be pulled away from the fracture sit by periosteum

159

What happens to fragments of bone pulled away from the fracture site?

It is removed by osteoclasts

160

When is a bony union and callus formation not possible?

If a fracture involves loss of bone fragments

161

What is the purpose of bone banks?

They are available to supply viable bone for grafting purposes

162

What happens to bone in bone banks?

It’s frozen then used by orthopaedic surgeons

163

What are the types of bone graft?

- Autograft
- Homograft 
- Heterograft

164

Where does the bone graft in an autograft come from?

The person themselves

165

Where does the bone graft come from in a homograft?

A different human

166

Where does the bone graft come from in a heterograft?

A different species

167

What is the advantage of using calf bone in heterograft?

It loses antigenicity with refrigeration