Week 1 - Bones Flashcards

1
Q

What are the diff. tissues working together in the bone

A

Osseous tissue

Cartilage

Dense connective tissue

Epithelium

Adipose tissue

Nervous tissue

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

What % of human body weight is bone? And what % of the body’s calcium does it store?

A

18%

99%

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

What does red bone marrow consist of?

A

Developing blood cells

Adipocytes

Fibroblasts

Macrophages w/in a network of reticular fibres.

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

Where can red bone marrow be found

A

Developing bones of the foetus + in adult bones:

  • Pelvic bones
  • Ribs
  • Sternum
  • Vertebrae
  • Skull
  • Ends of bones of humerus
  • Femur
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Bone marrow for newborns

A

All red + involved in hemopoeisis

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

What’s in the extracellular matrix?

A

15% H20

30% collagen fibres

55% crystallised mineral salts

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

Whats the most abundant crystallised mineral salt in the body?

A

Calcium phosphate

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

What does calcium phosphate do in the bones?

A

Combines w. calcium hydroxide —-> Crystal of hydroxyapatite.

As these form they combine w. other mineral salts i.e calcium carbonate.

Then crystallise when deposited in the framework formed by collagen fibres of the extracellular matrix == Calcification

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

What is calcification initiated by?

A

Osteoblasts

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

External functions of the skeletal system

A

Protection of internal organs

Movement facilitation

Supports the body

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

Internal functions of the skeletal system

A

Prod. of blood cells

Storage of minerals

Storage of TG

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

Where are TG stored in the skeleton?

A

Yellow bone marrow

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

What are the 4 main aspects of a long bone

A

Epiphysis

Diaphysis

Periosteum membrane

Endosteum membrane

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

Define the epiphysis

A

Ends of bones

Joint surface is covered w. articular cartilage

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

What separates the diaphysis from the epiphysis

A

Epiphyseal line

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

At around what ages do long bones stop growing in LENGTH?

A

18-25

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

What happens after long bones stop growing in length?

A

Epiphyseal cartilage disappears

Epiphyseal plate closes

Becomes visible on x-rays as an epiphyseal line

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

Define metaphyses

A

Regions between diaphysis + epiphysis

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

What does a metaphysic contain on a growing bone?

A

An epiphyseal/growth plate

Hyaline cartilage that allows the diaphysis fo the bone to grow in length

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

Define the diaphysis

A

Long, tubular shaft of the bone.

A collar of compact bone surrounds a central medullary/marrow cavity.

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

Define the medullary cavity

A

In the diaphysis.

Filled w. yellow bone marrow + in adults contains fat.

Interior of all bones consists largely of spongy bone.

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

Where is the periosteum

A

Covers the outer bone surface

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

What does the periosteum consist of

A

Dense irregular connective tissue

Osteoblasts

Nerve fibre blood - secured by sharpers fibres

Lymph vessels - secured by sharpeys fibres

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

Where is the endosteum

A

Covers the internal bone surfaces

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

Define the articular cartilage

A

Thin layer of hyaline cartilage

Covers epiphysis where bone forms an articulation w, another bone = joint.

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

What is the function of articular cartilage

A

⬇️ friction + absorbs shock at freely moveable joints.

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

Why is the repair of damaged articular cartilage limited?

A

Due to lack of perichondrium + bv.

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

What are the 2 main types of bones?

A

Cortical (compact/hard)

Trabecular (cancellous/spongy/soft)

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

Cortical (compact/hard) bone

A

Low porosity (5-10%)

Strong + dense (80% of skeleton)

Epiphysis (thin shell)

Diaphysis (shaft, thicker)

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

Trabecular (cancellous/spongy/soft)

A

High porosity (30-90%)

Lighter + less dense than cortical

20% of skeleton

Remaining space is filled w. marrow + fat

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

List the main components of the microscopic structure of compact bone

A

Osteon

Osteoblasts + clasts

Osteocytes

Osteoid

Osteoprogenitor cells

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

COMPACT BONE

Osteon

A

Repeating structural units of compact bone tissue.

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

COMPACT BONE

Osteoblasts

A

Make + deposit components of bone extracellular matrix.

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

Where are osteoclasts often found?

A

In the endosteum lining the marrow cavity.

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

What do osteoclasts do

A

Degrade + resorb bone for remodelling.

Secrete protein-digesting enzymes.

Dissolve bone matrix + release stored minerals (osteolysis).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Define osteocytes

A

“watcher cells”

Sit in bone + monitor its current status.

Mature bone cells that maintain protein + mineral content of bone matrix.

Also help repair damaged bone.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Where can osteocytes be found

A

Between lamellae of matrix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What is the osteoid?

A

Unmineralized bone matrix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What are osteoprogenitor cells?

A

Mesenchyme stem cells that divide to prod. osteoblasts.

Only bone cells that undergo cell division.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Define concentric lamellae

A

Circular plates of mineralised extracellular matrix of increasing diameter, surrounding a small network of bv + nerves located in the central canal.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What are lacunae?

A

Small spaces between the conc. lamellae that contain osteocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Canaliculi

A

Radiate from the lacunae in all directions.

Filled w. extracellular fluid.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

What can be found in the canaliculi

A

Slender fingerlike processes of osteocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

What do the canaliculi connect what with

A

Lacunae w. each other + w. central canals.

Provide routes for nutrients +O2 to reach osteocytes + for removal of wastes.

45
Q

How are osteons arranged

A

In same direction + parallel to the length of the diaphysis.

As a result, the shaft of the long bone resists bending or fracturing even when considerable force is applied from either end.

46
Q

Interstitial lamellae

A

Areas between neighbouring osteons

47
Q

How do bv + nerves from the periosteum penetrate the compact bone?

A

Through volkmanns/perforating canals

48
Q

Does spongy bone contain osteons?

A

NO

49
Q

Where is spongy bone always located

A

In the interior of the bone + protected by a covering of compact bone.

50
Q

What does spongy bone consist of

A

Lamellae arranged in an irregular pattern of thin columns = trabeculae.

51
Q

What are the spaces between the trabeculae filled with?

A

Red bone marrow

52
Q

What do trabeculae consist of

A

Concentric lamellae

Osteocytes in the lacunae

Canaliculi that radiate outward from the lacunae.

53
Q

Where do trabeculae lie?

A

Along lines of stress - helping bones resist stresses + transfer force w.out it breaking.

54
Q

Where can spongy bone be found?

A

Interior bone tissue of short, flat, sesamoid + irregularly shaped bones.

In long bones - Core of epiphysis

Tends to be located where bones aren’t heavily stressed or where stresses are applied from many directions.

55
Q

How are bones connected to homeostasis?

A

Bone building, maintenance + bone recycling must balance.

Higher resorption than formation = weaker bones.

56
Q

Bone Adapt. Through exercise

A

Wolff’s law holds that a bone grows or remodels in response to the forces which act on it.

Changes in bone density in response to exercise + tension + compression forces must balance.

57
Q

Where in the bones are BV abundant?

A

Parts containing red bone marrow, pass into bones from periosteum.

58
Q

Where do the Periosteal arteries enter the diaphysis through?

What do they do?

A

Interosteonic canals accompanied by nerves.

Supply periosteum + outer part of compact bone.

59
Q

What does the large nutrient artery do upon entering the medullary cavity?

A

Divides into proximal + distal branches that course toward each end of the bone.

60
Q

What do the Proximal + distal branches do?

A

Supply inner part of:

  • compact bone tissue of diaphysis
  • spongy bone tissue
  • red bone marrow

as far as the epiphyseal plates.

61
Q

What type of arteries are the ends of long bones supplied by?

A

Metaphyseal + epiphyseal arteries

62
Q

What are the 2 main methods of bone formation?

A

Intramembranous ossification

Endochondral ossification

= Both seen during embryonic development

63
Q

Where does intramembranous ossification occurs?

A

W/in mesenchyme

64
Q

What type of process is endochondral ossification?

A

Continuous

65
Q

How does endochondral ossification begin?

A

When chemical messages are sent to mesenchyme cells

66
Q

Endochondral ossification

What happens once chemical messages are sent to the mesenchyme cells

A

Causes them to crowd together in the shape of the future bone + develop into CHONDROBLASTS

67
Q

Endochondral ossification

What happens once the chondroblasts have been developed

A

Secrete extracellular matriculates which prod. a hyaline cartilage model

68
Q

Endochondral ossification

What happens to the mesenchyme cells surrounding the hyaline cartilage model

A

Condense to form perichondrium.

69
Q

Endochondral ossification

What happens as the chondroblasts become encased in the extracellular matrix?

A

They differentiate into CHONDROCYTES.

70
Q

Endochondral ossification

What are the 2 methods in which the hyaline cartilage model grows?

A

Interstitial growth

Appositional growth

71
Q

Endochondral ossification

Interstitial growth

A

When chondrocytes undergo continual cell division + more extracellular matrix is secreted.

Occurs from w/in the model + ⬆️ bone length

72
Q

Endochondral ossification

Appositional growth

A

Occurs when new chondroblasts continually develop from the outer perichondrium.

They secrete new matrix material + result in ⬆️ bone model WIDTH.

73
Q

Endochondral ossification

What happens as the hyaline cartilage model grows?

A

Central chondrocytes hypertrophy

+

Surrounding extracellular matrix calcifies.

74
Q

Endochondral ossification

What happens once the extracellular matrix has been calcified?

A

Nutrients can’t diffuse through = encased chondrocytes die = leaving open spaces.

75
Q

Endochondral ossification

Extracellular matrix has been calcified - nutrients can’t diffuse through.

What happens next?

A

Nutrient artery passes through:

  • perichondrium
  • nutrient foramen

then burrows into central region of calcifying cartilage model.

76
Q

Endochondral ossification

What happens once the nutrient artery passes through the nutrient foramen?

A

Stimulates new cells in perichondrium to differentiate into osteoblasts – eventually forming the periosteum.

77
Q

Endochondral ossification

When does the primary ossification centre grow?

A

When periosteal capillaries grow into the calcified cartilage + chondrocytes hypertrophy + die.

78
Q

Endochondral ossification

Where does the primary ossification centre grow?

A

W/in the shaft of the bone

79
Q

Endochondral ossification

When is the spongy trabecular bone formed?

A

When osteoblasts replace the calcified cartilage + secrete bone extracellular matrix = osteoid.

80
Q

Endochondral ossification

What do the invading osteoclasts do?

A

Break down some of the central trabecular bone to form a medullary cavity in the diaphysis (shaft) of the bone.

Surrounding bone is replaced by compact bone.

81
Q

Endochondral ossification

What happens when the surrounding bone is being replaced by compact bone?

A

Branches of the epiphyseal artery invade the epiphyses.

== Induces a 2ndary ossification centre.

82
Q

Endochondral ossification

What happens at the 2ndary ossification centre?

A

Cartilage is replaced by bone

but

No medullary cavity is formed.

83
Q

Endochondral ossification

Lastly, what happens to the hyaline cartilage covering the epiphysis?

+ then what happens to the hyaline cartilage between the epiphysis + diaphysis?

A

Covering epiphysis - Develops into articular cartilage

Between ep. + diaphysis - Remains + forms epiphyseal growth plate.

84
Q

Where does bone develop from in intramembranous ossification?

A

A fibrous membrane

85
Q

What is intramembranous ossification responsible for?

A

Prod. flat bones in skull + clavicle

86
Q

What 4 steps are in intramembranous ossification?

A

Ossification centre

Calcification of matrix

Formation of trabeculae

Development of periosteum

87
Q

Intramembranous ossification

  1. Ossification centre

What happens?

A

Chemical messages cause mesenchyme cells to crowd together to form ossification centre.

88
Q

Intramembranous ossification

  1. Ossification centre

What happens to the mesenchyme cells once they’ve formed the ossification centre?

A

Differentiate into osteogenic cells

Later osteoblasts – which secrete extracellular matrix.

89
Q

Intramembranous ossification

  1. Calcification of matrix

What do the osteoblasts do?

A

Secrete a mix of collagen fibres + osteoid.

90
Q

What does osteoid do over time?

A

Calcifies

91
Q

Intramembranous ossification

  1. Calcification of matrix

What happens as the layers of calcified matrix are continuously laid down?

A

The trapped osteoblasts, now osteocytes, lie w/in lacunae of an osteon + project their cytoplasmic processes into the radiating canaliculi.

92
Q

Intramembranous ossification

  1. Formation of trabeculae
A

Trabeculae bone - Formed by the accumulating layers of calcified matrix

93
Q

Intramembranous ossification

  1. Development of the periosteum
A

Mesenchyme cells condense around the outside of bone to form periosteum.

Thin layer of compact bone is deposited over surface layers of spongy bone while the rest remains in centre to form DIPLOE.

94
Q

Intramembranous ossification

  1. Development of the periosteum

What does the vascular tissue in the diploe differentiate into?

A

Red bone marrow.

95
Q

Growth in length of long bones

What part of the cartilage grows by interstitial growth?

A

Cartilage on side of the epiphyseal plate closest to the epiphysis.

96
Q

What are the 4 zones of which the epiphyseal growth plate is divided up into?

A

Zone of resting cartilage

Zone of proliferating cartilage

Zone of hypertrophic cartilage

Zone of calcified cartilage

97
Q

EPIPHYSEAL GROWTH PLATE

Zone of resting cartilage

A
  • Small scattered chondrocytes on side of epiphyseal plate facing epiphysis.
  • Chondrocytes don’t participate in bone growth
  • Instead, they attach epiphyseal plate to epiphysis of bone.
98
Q

EPIPHYSEAL GROWTH PLATE

Zone of proliferating cartilage

A
  • Larger chondrocytes in tall columns.
  • Undergo interstitial growth as they divide quickly + secrete extracellular matrix.

== Causing epiphysis to move away from diaphysis == lengthening bone.

99
Q

EPIPHYSEAL GROWTH PLATE

Zone of hypertrophic cartilage

A
  • Mature chondrocytes
  • Enlarge as cells hypertrophy
  • Lacunae surrounding cells erode, leaving large spaces.
100
Q

EPIPHYSEAL GROWTH PLATE

Zone of calcified cartilage

A
  • Thin layer of epiphyseal plate
  • Surrounding matrix calcifies + chondrocytes die off.
  • Where endochondral bone formation occurs
101
Q

Where are osteoclasts derived from?

A

Stem cells that produce macrophages.

Huge cells derived from the fusion of 50 monocytes + are conc. In the endosteum.

102
Q

Do osteocytes divide?

A

NO

103
Q

Are osteoprogenitor cells specialised?

A

NO

104
Q

Where are osteoprogenitor cells located?

A

Inner cellular layer of periosteum

105
Q

What do osteoprogenitor cells assist with?

A

Fracture repair

106
Q

What does each osteon consist of?

A

Osteocytes arranged in a conc. lamellae around a central canal containing bv.

107
Q

Osteoblasts are IMMATURE bone cells that secrete matrix compounds, what do they become after this when surrounded by CALCIFIED BONE?

A

Osteocytes

108
Q

What is cartilage on the diaphysial side of the bone replaced with?

A

Bone from endochondral ossification.