Skeletal Flashcards

1
Q

How does cartilage receive nutrients?

A

Diffusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the two means of cartilage growth and development?

A

Appositional growth

Interstitial growth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Describe appositional growth of cartilage

A

New cartilage is added to the surface of the older cartilage by chondroblasts from the deep perichondrium.

The chondroblasts then become more chondrocytic over time.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Describe interstitial growth of cartilage

A

New cartilage is formed within older cartilage by chondrocytes that divide and produce new matrix.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the three cartilage types?

A

Hyaline
Fibrous
Elastic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How does cartilage underpin long bone growth?

A

Hyaline cartilage present in the epiphysial plates of the long bones

New cartilage forms on the epiphysis side of the epiphysial plate and its ossifies into bone on the diaphysis side.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe how events at epiphysial plates lead to long bone growth?

A

Chondrocytes proliferate in the upper plate and arrange into vertical stacks, the cells hypertrophy lower down before they die and are ossified into the bone matrix.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is bone tissue made of?

A

Tissue made up if several cells and connective fibres

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are functions of bone?

A

Load bearing

Protection (e.g. skull)

Attachment for muscles

Storage of calcium + phosphate

Contains bone marrow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What does bone consist of?

A

Cellular component and ECM mineralised by deposition of hydroxyapatite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What happens to the ECM in bone?

A

Mineralised by desposition of hydroxyapatite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

2 features of bone

A

Resistant to tensile and compressive forces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What happens in rickets?

A

Lack of Vitamin D3 so failure to absorb calcium -bones bend

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What happens as you add acid to bone, why?

A

Lose compressive strength

Becomes flexible as demineralised

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What happens as you heat bone, why?

A

Collagen denatures and bone shatters when tensile force (but can deal with compressive forces)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What gives compressive strength to bone?

A

Hydroxyapatite crystals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What gives tensile strength to bone?

A

Collagen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What do calcium hydroxyapatite crystals attach to?

A

Collagen fibres

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What 2 things does bone remodelling allow?

A

Bone shape maintenance during growth and fracture healing.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are osteogenic cells derived from?

A

Mesenchyme

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are osteogenic cells?

A

Undifferentiated, pluripotent stem cells which can produce bone forming cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Where are osteogenic cells found in adults?

A

Periosteum and endosteum in adults

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Why are osteogenic cells important?

A

Remodelling, growth and repair of bones by providing new osteoblasts (when required)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What do osteoblasts do?

A

Secrete osteoid, make new bone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What happens to osteoid after secreted from osteoblasts?

A

Initially uncalcified but then mineralsed as it moves away from osteoblasts by deposition of hydroxyapatite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

When are osteoblasts recruited?

A

When bone needs to grow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What do osteoclasts do?

A

Bone removal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What do osteoclasts allow?

A

Bone remodelling

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Describe structure of osteoclasts?

A

Multinucleated marcophages

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

How do osteoclasts remove bone?

A

Acid and protease secretion, forming Howship’s lacunae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What are Howship’s lacunae?

A

Depression of bone surface where resorption has occured

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

How are osteoclasts anchored to bone?

A

Attach via integrins to matrix protein osteopontin in the bone matrix.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What do osteocytes do?

A

Preserve bone matrix, sitting in lacunae (surrounding bony matrix)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What are two types of bone formation?

A

Intramembranous and endochondral

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Which bones form from intramembranous ossification?

A

Flat skull bones, mandible, maxilla and clavicle

36
Q

Describe intramembranous ossification?

A

Bone formation from connective tissue not cartilage

37
Q

What are 4 steps of intramembranous ossification?

A

1) Osteogenic progenitor - osteoblasts - ossification centre
2) Osteoid secreted, mineralised by hydroxyapaptie deposition. Osteoblasts trapped in matrix - osteocyte
3) Spongy bone formed: trabeculae form around blood vessels, blood vessel outside spongy bone condenses -periosteum
4) Peripheral osteoid condenses - compact bone

38
Q

What is definition of endochondral ossification?

A

Initial hyaline cartilage model continues to grow then is calcified by chondrocytes

39
Q

What is osteoid?

A

Unmineralized, organic portion of the bone matrix that forms prior to the maturation of bone tissue.

Gelatinous substance made up of collagen, a fibrous protein, and mucopolysaccharide, an organic glue

40
Q

What forms around hyaline cartilage in endochondral ossification?

A

Periosteum

41
Q

Are bones vascular?

A

Yes

42
Q

What does ECM of bone consist of?

A

Collagen, hydroxyapatite, proteoglycans

43
Q

What happens in endochondral ossification?

A

Osteoblasts secrete osteoid outside cartilage -forming compact bony collar

Inner cartilage ossifies -primary ossification centre in diaphysis

Vessels in periosteum pass through bony collar, via nutrient foramen to inner cartilage (osteoblasts and osteoclasts can pass)

Remaining cartilage broken down by osteoblasts

Osteoblasts secrete osteoid forming trabeculae

44
Q

What happens to diaphysis and medullary cavity in endochondral ossification?

A

Undergoes elongation and appositional growth

45
Q

When and where do secondary ossification centres form?

A

Before birth, at epiphysis

46
Q

How does secondary ossification centre ossify differently to primary?

A

Spongy bone formed not compact.

Layer of hyaline cartilage remains on end of bone

Epiphysial growth plates do not mineralise until maturity (so long bone growth until adult hood.)

47
Q

What is epiphysial plate made of and what happens to it?

A

Cartilage, it grows and divides so more cells on underside laid down and bone shaft left increases

48
Q

What are the stages of growth of long bone?

A
Resting cartilage
Proliferation
Hypertrophy
Calcification
Ossified bone
49
Q

What happens in the zone of resting cartilage?

A

Cartilage attaches to epiphysis

50
Q

What happens in the zone of proliferation at a epiphysial plate?

A

New cartilage made on epiphysial side of plate as chondrocytes divide form stacks of cells

51
Q

What happens in the zone of hypertrophy?

A

Chondrocytes mature and enlarge

52
Q

What happens in the zone of calcification?

A

Cartilage matrix digested by osteoclasts and calcified + ossified by osteoblasts

53
Q

What happens to chondrocytes in zone of calcification?

A

Chondrocytes die (don’t receive enough nutrients)

54
Q

What happens in osteoporosis?

A

Bone breakdown > bone formation.

i.e. too much osteoclast activity or too little osteoblast activity

55
Q

What does growth plate extend?

A

Diaphysis

56
Q

What becomes more likely in osteoporosis?

A

Hip fractures

57
Q

Describe the process of bone remodelling?

A

Force/stimulus to remodel perceived by osteocyte

Osteoclasts recruited and remove unwanted bone

Osteoblasts then recruited to form new bone

58
Q

What happens in appositional bone growth?

A

Growth by increasing layers (i.e. diameter of bone around diaphysis increases)

59
Q

What is the mechanism for appositional growth?

A

Ostoeblasts secrete osteoid against shaft of cartilage model

60
Q

What are the different names for spongy bone?

A

Spongy/trabecular/cancellous

61
Q

Two types of bone in a long bone?

A

Spongy or compact bone

62
Q

Where is spongy bone found?

A

Interior of epiphyses

63
Q

Describe structure/feature of cancellous bones?

A

Many interconnecting cavities

64
Q

Describe arrangement of spongy and compact bone?

A

Interior of epiphyses is spongy bone, surrounded by compact bone (outer layer of diaphysis)

65
Q

Describe how spongy and compact bones are arranged/joined?

A

Trabeculae of cancellous bone attach to overlying compact bone at right angle resist compressive forces

66
Q

What is the arrangement of spongy and compact bone in flat bones?

A

Cancellous bone sandwiched between 2 plates of compact bone

67
Q

What are the alternate names for primary and secondary bone?

A

Woven bone

Lamellar bone

68
Q

Describe the structure of woven bone?

A

Collagen fibres in irregular arrangement
Little mineralisation
Lots of osteocytes

69
Q

What happens to primary/woven bone in adults?

A

Replaced by secondary bone

70
Q

Where is primary bone found?

A

Tooth socket

71
Q

Secondary bone can be either?

A

Compact or spongy

72
Q

Describe structure of secondary bone?

A

Cylindrical Osteons connected by canaliculi

Osteon contains Haversian canal along length of diaphysis

Collagen fibres arranged in lamellae/rows. Lamellae arranged around central (Haversian) canal (contains neurovascular bundle)

73
Q

Where is red bone marrow found?

A

Red bone marrow is found between the trabeculae in spongy bone

74
Q

Where are osteocytes found relative to lamellae?

A

Between concentric layers of lamellae

75
Q

What makes up lamellae in secondary bone?

A

Collagen fibres arranged in lamellae/rows

76
Q

What connects osteons?

A

Canaliculi

77
Q

Why is trabecular bone beneficial?

A

Lighter (can be moved easily by muscle)

78
Q

What does bone mineralisation prevent?

A

Diffusion of nutrients & waste products

79
Q

Describe where vessels are found in bone?

A

In central canal and joined through perforating/Volkman’s canals horizontally

80
Q

What are Volkmanns canals?

A

Horizontal connections between Haversian canals (blood vessels)

81
Q

What do osteocytes extend, what does this allow?

A

Cytoplasmic processes into canliculi - allows exchange of nutrients/waste between bone and blood and commuication between osteocytes

82
Q

How are osteocytes linked to surface osteoblasts and other osteocytes, why is linkage between osteocytes important?

A

Canaliculi and gap junctions - osteocyes can communicate when force applied (sense lines of stress)

83
Q

What does red bone marrow do?

A

Make blood cells

84
Q

What does yellow bone marrow do?

A

Store fat

85
Q

What bone growth occurs at epiphysial plates?

A

Longitudinal bone growth

86
Q

What is bone growth from the inside driven by chondrocyte hypertrophy?

A

Interstitial bone growth