Bone Flashcards
describe the haversian system
osteoclasts form a cavity in the bone> blood vessel comes in> osteoblasts line cavity> add layers inwardly toward vessel with collagen alternating directions.
Osteocytes present in layers
what is woven bone. give 3 features. what eventually happens?
new bone (during development or repair). more cellular, more collagen, no haversian systems. Eventually osteoblasts and clasts remodel
what is mechanotransduction and which cells exhibit this?
detection of the direction of stress through a bone. osteocytes
what is a comminuted fracture?
bone smashed into many pieces
what is a pathological fracture?
damage in which the underlying process is not trauma
stages of bone repair?
inflammation, reparative (soft and hard callus), remodelling.
what is osteoporosis. give 2 MOAs
decreased bone mass that increases likelihood of fracture.
Menopause - decreased estrogen & increase osteoclast
Aging - decease osteoblast
describe the imflammation stage of repair. give time frame
Haematoma formation then Granulation tissue formation. first few days
describe the repartive stage of repair. give time frame
soft callus (cartliage formation. Holds fractured ends together.) days to weeks. Hard callus - osteoid formation and ossification creates woven bone. Weeks to months
describe the remodelling stage of repair. give time frame
woven bone to lamellar bone along lines of stress. months to years.
role of oestrogen in relation to bone?
decrease osteoclast activity
describe how osteoporosis affects bone
loss of bone cells and matrix. The loss of trabeculae reduce the cross-sectional area resulting in a relatively greater load on the bone
name the 3 types of antiresoptive drugs
bisphosphates, selective oestrogen receptor modulators(raloxifene), RANKL inhibitors
denosumab is a what?
RANKL Inhibitor
PTH as a drug?
paradoxical - small amounts (once per day) results in anabolism, whereas excessive amounts will cause catabolism by promoting Clast actvity
MOA of Bisphosphates
ingested by osteoclasts - inhibit recruitment and promote apoptosis. poorly absorbed but remain in bone for long periods
most common cause of osteomyelitis?
Staph A.
what is different in terms of infection position in regards to infants?
infection can cross growth plate to invade epiphysis and joint
which Arthritis is associated with morning stiffness?
Rheumatoid
fibrillations of cartilage, eburnation of bone are histological hallmarks of what?
osteo A
histology of RA (3)
villous hyperplasia, mononuclear infiltrate, germinal centre
histology of a rheumatoid nodule
typical granulomatous inflammation. Central necrosis, surrounded by epithelioid macrophages then lymphocytes and fibrosis.
histology of a gouty tophus
granulomatous inflammation. Central urate deposits surrounded by epithelioid macrophages & MNG cells, fibrosis on outskirts
what is podagra?
gout in big toe
