bone structure and function

Question 1

what is bone composed of

Answer 1

living cells in mineralised extracellular matrix

Question 2

what is hydroxyapatite

Answer 2

hydrated crystalline material of calcium and phosphate

Question 3

bone matrix

Answer 3

collagen I and V

crystals of carbonated hydroxyapatite

Question 4

bone function

Answer 4

support
protect
movement

Question 5

metabolic function of bone

Answer 5

haematopoiesis (production of new blood cells)

calcium homeostasis

Question 6

bone types

Answer 6

cortical 
outer, strong 
trabecular
inner, spongy meshwork
woven
first bone formed, remodelled

Question 7

what is found on the outside of cortical bone

Answer 7

periosteum

contains collagen, fibroblasts, stemcells

Question 8

what covers the outside of trabular bone

Answer 8

endosteum

Question 9

describe trabecular

Answer 9

contins matrix
ostocytes in matrix
osteoblasts on edges

Question 10

describe woven bone

Answer 10

unorganised
cellular
becomes mineralised

Question 11

cell types in bone

Answer 11

osteoclast
osteoblast
osteocyte 
pre-osteoblast?
bone lining cells
osteoprogenitor cells

Question 12

phases of remodelling

Answer 12

resorption phase
bone ECM destroyed
3 weeks
bone formation
new ECM formed/mineralised 
3-4 months

Question 13

what is important for maintenance and formation

Answer 13

mechanical forces

Question 14

systemic factors stimulating bone resorption

Answer 14

parathyroid hormone - stimulate osteoblasts to produce Oc stim factors
1-25, dihydroxy vit D3
thyroid hormone

Question 15

systemic factors promoting bone formation

Answer 15

parathyroid

1-25 dihydroxy vit D3

Question 16

local factors that stimulate bone resorption

Answer 16

inflammation

tumour necrosis factors

Question 17

local factors promoting bone formation

Answer 17

bone morphogenic protiens

Question 18

bone diseases

Answer 18

osteoporosis
- loss of oestrogen 
periodontitis
pagets disease
- bone not fully mineralised 
rheumatoid arthritis

Question 19

bone remodelling process

Answer 19

sclerotin prevents osteoblasts forming new bone
micro fracture sets off one remodelling, osteocytes SOS factor
activate storm cells - producing MCSF
stimulates osteoclast precursors
precursors carry RNAK on surface
stroll cells produced daughter cells with RNAK L
RANK L activates RANK
preosteoclasts fuse and form multinucleate osteocloasts
bone linig cells allow osteoclasts to adhere - release HCL to dissolve mineral and cathepsin K to chew ECM forming Howships lacuna
osteoclasts die by apoptosis, GF released
daughter cells produce OPG (sits over RANK)
osteoblasts create matrix ,mineralised
some osteoblasts lett to form osteocytes

Question 20

what does sclerostin do

Answer 20

prevents Ob making bone

Question 21

function of osteocyte s

Answer 21

sense what is happening in bone

secrete schlrostin