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Flashcards in SKELETAL TISSUE Deck (84)
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1
Q

what does the skeletal system include?

A
bones of skeleton
cartilage
ligaments 
tendons 
CT
2
Q

what is the function of skeletal system?

A

Structural support
Levers:change direction of forces generated by skeletal muscle
protection, storage, blood cell production

3
Q

what is cartilage?

A

supporting CT

4
Q

what does cartilage contain?

A

gelatinous matrix: ground substance and fibres

5
Q

what are cartilage cells?

A

chondrocytes occupy lacunae

6
Q

what are the characteristic of cartilage?

A

Poorly vascularised
Exchange nutrients/waste occurs by diffusion
heals slowly

7
Q

what is cartilage derived from?

A

embryonic mesoderm

8
Q

what is mesoderm made of?

A

mesenchyme

9
Q

how is cartilage separated from surrounding tissue?

A

by perichondrium

10
Q

how many layers does perichondrium have?

A

2 layers
Outer fibrous irregular CT layer
Inner cellular layer

11
Q

what are the 3 types of cartilage?

A

hyaline, elastic, fibrocartilage

12
Q

what does hyaline cartilage contain?

A

translucent matrix

covered by dense perichondrium

13
Q

what does the matrix contain?

A

closely packed collagen fibres

14
Q

what does the matrix provide?

A

Provides tough but flexible support

15
Q

give examples of hyaline cartilage

A

Connect ribs & sternum

Nasal cartilages & resp tract

16
Q

what is articular cartilage?

A

cover opposing bone surfaces joints e.g. knee & elbow

17
Q

what is elastic cartilage?

A

Contains many elastic fibres: resilient & flexible

Tolerates distortion - returns back to shape

18
Q

give examples of elastic cartilage?

A

External flap outer ear, epiglottis, larynx

19
Q

what does fibrocartilage contain?

A

little ground substance

matrix dominated by large collagen fibres which are densely interwoven

20
Q

what is a characteristic of fibrocartilage?

A

Tough & durable:
resists compression
absorbs shocks
prevents damaging bone to bone contact

21
Q

give examples of fibrocartilage

A

Pads between spinal vertebrae
Between pubic bones in pelvis
Around/within some joints & tendons

22
Q

what are the 2 mechanism of cartilage growth?

A

interstitial

appositional

23
Q

what happens in interstitial growth?

A

Chondrocytes: undergo cell division -additional matrix

Enlarges cartilage from within

24
Q

what is interstitial growth important in?

A

Important during embryonic development

25
Q

what happens in appositional growth?

A

New layers added to surface

Inner layer of perichondrium divides

26
Q

what happens to cells in appositional growth?

A

cells - immature chondrocytes - cartilage matrix - differentiate mature chondrocytes

27
Q

what is the source of new cartilage cells?

A

fibroblasts

28
Q

why is appositional growth important?

A

increases size of cartilage by adding to outer surface

29
Q

what is the role of hyaline cartilage in growing bone?

A

Initial skeleton of foetus

Each cartilage is miniature bone model

30
Q

what is the precursor of bone developed by?

A

endochrondral ossification

31
Q

what is osteogenesis?

A

Bone formation & growth

32
Q

when does osteogenesis take place?

A

begins 6 wks after fertilisation, continues through fertilisation

33
Q

what is ossification?

A

replacement of cartilage & CT by bone

34
Q

what are the 2 forms of ossification?

A

Endochondral

Intramembranous

35
Q

what is endochondral ossification?

A

Bone replaces existing cartilage

6 wk embryo cartilaginous models of limb bone replaced by bone

36
Q

what happens in endochondral ossification?

A

Begins near middle of shaft 1o centre of ossification
Centre of epiphyses (head) calcify: 2o ossification centre
Epiphyses: filled with spongy bone

37
Q

what bones are affected by endochondral ossification?

A

extremities & axial weight bearing

e.g. Femur, vertebrae

38
Q

what is intramembranous ossification?

A

Bone develops from mesenchyme / CT

Stem cells within connective tissue differentiate osteoblasts

39
Q

what happens in intramembranous ossification?

A

Mesenchymal cells cluster & secrete matrix
Calcification occurs mesenchymal cells osteoblasts
Ossification begins = Ossification Centre
1st forms spongy bone: remodelling:
compact bone

40
Q

what bones are affected by intramembranous ossification?

A

flat bones: skull, mandible, clavicle

41
Q

what are the components of bone?

A

supporting CT, specialised cells, extracellular fibres, ground substance, calcium phosphate, collagen fibres, cells

42
Q

how is blood supplied to bone?

A

Nutrient artery
Metaphyseal vessels
Periosteal vessels

43
Q

what are long bones?

A

long & slender

44
Q

give examples of long bone

A

thigh (femur)

arm (humerous)

45
Q

what are short bones?

A

small & boxy

46
Q

give examples of short bone

A

carpals (wrist)

tarsals (ankles)

47
Q

what are flat bones?

A

thin & parallel surfaces

48
Q

give examples of flat bones

A

parietal, ribs & scapula

49
Q

what are irregular bones?

A

complex, notched/ridged surfaces

50
Q

give examples of irregular bones

A

vertebrae, pelvis

51
Q

what are sesamoid bones?

A

Small & flat

52
Q

give examples of sesamoid bones

A

develop inside tendons near joints eg kneecap

53
Q

what are sutural bones?

A

Small, flat / irregular

54
Q

give examples of sutural bones

A

Between flat bones of skull

55
Q

what does a long bone contain?

A
Central shaft (diaphysis)
Expanded ends (epiphyses)
Central: marrow cavity
epiphyses of adjacent bones 
- articulate & covered by articular cartilage: hyaline
56
Q

what are compact/dense bones?

A

relatively solid
located on surface of bone
forms diaphysis

57
Q

what is spongy/cancellous bone?

A

forms open network
interior of bone
forms epiphysis

58
Q

what does the outer surface periosteum contain?

A

Fibrous outer layer & cellular inner layer

59
Q

what are osteocytes?

A

mature bone cells cannot divide, occupy a lacuna

60
Q

what is a lacuna?

A

pocket / layers of matrix = Lamellae

61
Q

what is a canuliculi?

A

passageways – link osteocytes

62
Q

what is the function of osteocytes?

A

maintain normal function by recycling Ca2+ salts
repair damaged bone
released from lacunae- less specialised cell type

63
Q

what are osteoblasts?

A

precursor cells

production of new bone: osteogenesis

64
Q

what is the function of osteoblasts?

A

make & release proteins / organic components of matrix

increase local conc of Ca2+ phosphate

65
Q

what do osteoblasts form?

A

Form osteocytes / develop from osteoblasts- surrounded by bone matrix

66
Q

what are osteoprogenitor cells?

A

mesenchymal cells =

stem cells which divide daughter cells  -osteoblasts

67
Q

what do osteoprogenitor cells do?

A

maintain populations of osteoblasts

68
Q

what are osteoclasts?

A

giant cells
remove bone matrix
derived from monocytes

69
Q

what do osteoclasts do?

A

Secrete acids & proteolytic enzymes dissolve bone matrix:
osteolysis

70
Q

what is the importance of osteoclasts?

A

regulation of Ca2+ & phosphate conc of body

71
Q

what is the functional unit in compact bone?

A

osteon / Haversian system

72
Q

how are osteocytes arranged in compact bone?

A

in concentric layers around central canal with blood vessels

73
Q

how are the lamellae arranged in compact bone?

A

form cylinders around central canal

74
Q

what are the perforating canals?

A

passageways

Blood vessels in canals supply blood to osteons

75
Q

what is compact bone surrounded by?

A

periosteum

76
Q

how is lamellae arranged in spongy bone?

A

form rods - trabeculae

77
Q

how is an open network created in spongy bone?

A

Frequent branching thin trabeculae

78
Q

what are the characteristics of spongy bone?

A

No capillaries or venules
Nutrients reach by diffusion along -
cannuliculi
red marrow found between trabeculae

79
Q

what is the structure of compact bone?

A

stresses come from limited range of directions

osteons aligned in same way

80
Q

what is the structure of spongy bone?

A

bones not heavily stressed / stresses arrive in many directions
lighter than compact

81
Q

what is the effect of aging on bones?

A

become thinner & weaker =osteopenia

82
Q

what is the effect of reduction in bone mass?

A

Osteoblast activity decreases

83
Q

what is osteoporosis?

A

Function of bone compromised

84
Q

what else is important in bone maintenance?

A

hormones