bone

Question 1

what does the axial skeleton consist of

Answer 1

skull
vertebral column
thoracic cage

Question 2

what does the appendicular skeleton consist of

Answer 2

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

Question 3

what are the functions of bone

Answer 3

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)

Question 4

what are the two kids of bone tissue

Answer 4

cancellous (spongy)

compact (dense)

Question 5

what is the thin cellular layer lining the marrow cavity called

Answer 5

endosteum

Question 6

where is compact bone found

Answer 6

shafts of long bone and forms the plates of flat bone

Question 7

where is spongy bone found

Answer 7

end of long bone and centre of flat and irregular bones

Question 8

what are the two types of ossification

Answer 8

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

Question 9

what is the function of compact bone

Answer 9

provides mechanical strength and protection of underlying organs

Question 10

function of cancellous bone

Answer 10

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

Question 11

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

Answer 11

impregnated with mineral salts-mainly calcium phosphate

Question 12

what is different about sesamoid bones compared to other bones

Answer 12

not covered in periosteum

Question 13

how is periosteum attached to bone

Answer 13

by collagen fibres called sharpey’s fibres

Question 14

describe the structure of the periosteum

Answer 14

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.

Question 15

what is the cement line

Answer 15

zone where newly formed osteoid meets original/existing bone

Question 16

how does cancellous bone become compact bone

Answer 16

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

Question 17

role of canaliculi

Answer 17

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

Question 18

what lines the lacunae and canaliculi

Answer 18

sheath of Neumann

Question 19

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

Answer 19

Haversian canal

carry nutrient providing blood vessels, lymphatic vessels and nerves

Question 20

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

Answer 20

volkmann’s canals

Question 21

difference between immature and mature bone

Answer 21

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

Question 22

what are the lacunae

Answer 22

spaces occupied by osteocytes

Question 23

difference between cancellous and compact bone

Answer 23

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

Question 24

why can bone resist fracture

Answer 24

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

Question 25

what is a key determinant of bone strength

Answer 25

exercise

Question 26

describe bone remodelling

Answer 26

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

Question 27

factors affecting bone stability

Answer 27

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

Question 28

what is osteogenesis imperfecta

Answer 28

brittle bone disease 
mutation of COL1A gene(affecting synthesis of type 1 collagen)
weak bones 
increased risk of fracture
shortened height and stature

Question 29

what is rickets

Answer 29

vit D deficiency
mainly affects children
poor calcium mobilisation 
ineffective mineralisation 
weakened bone development 
soft bone
shortened heigh and stature 
bowed legs

Question 30

what is osteomalacia

Answer 30

‘rickets’ in adults
vit d deficiency
lower mineralisation
increased osteoid but isn’t turning into mineralised bone.

Question 31

what happens in osteoporosis

Answer 31

loss of bone matrix, loss of structural density and demineralisation, increasing risk of fracture s
holes in trabecullae

Question 32

who does osteoporosis primary type 1 occur in

Answer 32

postmenopausal women

due to increase in osteoclasts as a result of loss of oestrogen

Question 33

who does osteoporosis primary type 2 occur in and why

Answer 33

older men and women
loss of osteoblast function
loss of both oestrogen and androgen

Question 34

what is the cause of secondary osteoporosis

Answer 34

drug therapy (corticosteroids)
malnutrition
metabolic bone diseases e.g hyperparathyroidism

Question 35

what is achondroplasia

Answer 35

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