bone Flashcards

1
Q

what does the axial skeleton consist of

A

skull
vertebral column
thoracic cage

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2
Q

what does the appendicular skeleton consist of

A

the upper and lower extremities, which include the shoulder girdle and pelvis.

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3
Q

what are the functions of bone

A

mechanical- protecting vital organs , form basis of levers for movement , provides framework for overall shape of human body
synthetic- haemopoiesis
metabolic- mineral storage (calcium and phosphorus ), fat storage and acid base homeostasis ( absorbs or releases alkaline salts to help regulate blood pH)

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4
Q

what are the two kids of bone tissue

A

cancellous (spongy)

compact (dense)

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5
Q

what is the thin cellular layer lining the marrow cavity called

A

endosteum

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6
Q

where is compact bone found

A

shafts of long bone and forms the plates of flat bone

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7
Q

where is spongy bone found

A

end of long bone and centre of flat and irregular bones

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8
Q

what are the two types of ossification

A

endochondral ossification- formation of long bones from a cartilage template. continued lengthening by ossification at epiphyseal plate. appositional growth
intra-membranous ossification- formation of bone from clusters of mesenchymal stem cells in the centre of bone. interstitial growth. flat bone use this

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9
Q

what is the function of compact bone

A

provides mechanical strength and protection of underlying organs

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10
Q

function of cancellous bone

A

provides space for red marrow to grow and develop. yellow bone marrow is also found here. this contains adipose tissue and acts as an energy source

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11
Q

what about the bone’s extracellular matrix gives it rigidity and hardness

A

impregnated with mineral salts-mainly calcium phosphate

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12
Q

what is different about sesamoid bones compared to other bones

A

not covered in periosteum

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13
Q

how is periosteum attached to bone

A

by collagen fibres called sharpey’s fibres

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14
Q

describe the structure of the periosteum

A

2 layers
outer layer is dense collagenous connective tissue with blood vessels, nerves and a few fibroblasts
inner layer: more loosely arranged. less vascular. provides the sharpey’s fibres. contains osteoprogenitor cells that differentiate into osteoblasts. called osteogenic layer.

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15
Q

what is the cement line

A

zone where newly formed osteoid meets original/existing bone

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16
Q

how does cancellous bone become compact bone

A

1) MSC convert into osteoblast that line trabeculae.
2) Lay down osteoid that is mineralised
3) Osteoblasts become trapped and are now osteocytes.
4) This is repeated
5) Central MSC covert into blood vessels, lymph vessels and nerves

17
Q

role of canaliculi

A

provide channels through which travel the cytoplasmic processes of osteocytes that form gap junctions with neighbouring cells.
also transports waste products to the vasculature

18
Q

what lines the lacunae and canaliculi

A

sheath of Neumann

19
Q

what is at the centre of osteons and what does this carry

A

Haversian canal

carry nutrient providing blood vessels, lymphatic vessels and nerves

20
Q

how do haversian canals communicate with marrow cavity, periosteum and each other

A

volkmann’s canals

21
Q

difference between immature and mature bone

A

immature has osteocytes in random arrangements and mature has them arranged in concentric lamellae of osteons

22
Q

what are the lacunae

A

spaces occupied by osteocytes

23
Q

difference between cancellous and compact bone

A

cancellous is not made of osteons but of trabeculae.
no canals in cancellous
no nerves, blood vessels or lymphatic vessels in cancellous

24
Q

why can bone resist fracture

A

great tensile and compressive strength. a degree of flexibility
different layers of lamellae can slide across each other. cells have h20 that resist compression

25
what is a key determinant of bone strength
exercise
26
describe bone remodelling
osteoclasts make a wide tunnel in bone. they use enzymes and acids to breakdown bone changing the bone into osteoid and release the osteocytes on the bone making them osteoblasts. osteoblasts can make a small tunnel of bone
27
factors affecting bone stability
ageing-decrease of oestrogen and testosterone . these hormones would normally suppress the proliferation and actions of osteoclasts causing increased resorption when levels are diminished. neoplasia- benign tumours (chondroma & osteoma), malignant tumour (chondrosarcoma & osteogenic sarcoma) disorders- achondroplasia, rickets, osteomalacia,osteoporosis
28
what is osteogenesis imperfecta
``` brittle bone disease mutation of COL1A gene(affecting synthesis of type 1 collagen) weak bones increased risk of fracture shortened height and stature ```
29
what is rickets
``` vit D deficiency mainly affects children poor calcium mobilisation ineffective mineralisation weakened bone development soft bone shortened heigh and stature bowed legs ```
30
what is osteomalacia
'rickets' in adults vit d deficiency lower mineralisation increased osteoid but isn't turning into mineralised bone.
31
what happens in osteoporosis
loss of bone matrix, loss of structural density and demineralisation, increasing risk of fracture s holes in trabecullae
32
who does osteoporosis primary type 1 occur in
postmenopausal women | due to increase in osteoclasts as a result of loss of oestrogen
33
who does osteoporosis primary type 2 occur in and why
older men and women loss of osteoblast function loss of both oestrogen and androgen
34
what is the cause of secondary osteoporosis
drug therapy (corticosteroids) malnutrition metabolic bone diseases e.g hyperparathyroidism
35
what is achondroplasia
inherited mutation in FGF3 receptor gene FGF promotes collagen formation from cartilage so endochondrial ossification is affected. short stature but normal sized head and torso