Bone

Question 1

describe the haversian system

Answer 1

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

Question 2

what is woven bone. give 3 features. what eventually happens?

Answer 2

new bone (during development or repair). more cellular, more collagen, no haversian systems. Eventually osteoblasts and clasts remodel

Question 3

what is mechanotransduction and which cells exhibit this?

Answer 3

detection of the direction of stress through a bone. osteocytes

Question 4

what is a comminuted fracture?

Answer 4

bone smashed into many pieces

Question 5

what is a pathological fracture?

Answer 5

damage in which the underlying process is not trauma

Question 6

stages of bone repair?

Answer 6

inflammation, reparative (soft and hard callus), remodelling.

Question 7

what is osteoporosis. give 2 MOAs

Answer 7

decreased bone mass that increases likelihood of fracture.
Menopause - decreased estrogen & increase osteoclast
Aging - decease osteoblast

Question 8

describe the imflammation stage of repair. give time frame

Answer 8

Haematoma formation then Granulation tissue formation. first few days

Question 9

describe the repartive stage of repair. give time frame

Answer 9

soft callus (cartliage formation. Holds fractured ends together.) days to weeks.
Hard callus - osteoid formation and ossification creates woven bone. Weeks to months

Question 10

describe the remodelling stage of repair. give time frame

Answer 10

woven bone to lamellar bone along lines of stress. months to years.

Question 11

role of oestrogen in relation to bone?

Answer 11

decrease osteoclast activity

Question 12

describe how osteoporosis affects bone

Answer 12

loss of bone cells and matrix. The loss of trabeculae reduce the cross-sectional area resulting in a relatively greater load on the bone

Question 13

name the 3 types of antiresoptive drugs

Answer 13

bisphosphates, selective oestrogen receptor modulators(raloxifene), RANKL inhibitors

Question 14

denosumab is a what?

Answer 14

RANKL Inhibitor

Question 15

PTH as a drug?

Answer 15

paradoxical - small amounts (once per day) results in anabolism, whereas excessive amounts will cause catabolism by promoting Clast actvity

Question 16

MOA of Bisphosphates

Answer 16

ingested by osteoclasts - inhibit recruitment and promote apoptosis. poorly absorbed but remain in bone for long periods

Question 17

most common cause of osteomyelitis?

Answer 17

Staph A.

Question 18

what is different in terms of infection position in regards to infants?

Answer 18

infection can cross growth plate to invade epiphysis and joint

Question 19

which Arthritis is associated with morning stiffness?

Answer 19

Rheumatoid

Question 20

fibrillations of cartilage, eburnation of bone are histological hallmarks of what?

Answer 20

osteo A

Question 21

histology of RA (3)

Answer 21

villous hyperplasia, mononuclear infiltrate, germinal centre

Question 22

histology of a rheumatoid nodule

Answer 22

typical granulomatous inflammation. Central necrosis, surrounded by epithelioid macrophages then lymphocytes and fibrosis.

Question 23

histology of a gouty tophus

Answer 23

granulomatous inflammation. Central urate deposits surrounded by epithelioid macrophages & MNG cells, fibrosis on outskirts

Question 24

what is podagra?

Answer 24

gout in big toe