Bone remodelling

Question 1

Why do you have bone turn over

Answer 1

Repair microdamage

Respond to mechanical stimuli

Store and release mineral

Question 2

Define modelling

Answer 2

Gross shape is altered, bone added or taken away

Question 3

Define remodelling

Answer 3

All of the bone is altered, new bone replaces old bone

Question 4

What are osteoclasts

Answer 4

Specialised macrophages

Question 5

Define coupling

Answer 5

Bone formation occurs at the site of previous bone resorption

Question 6

Define balance of remdelling

Answer 6

Amount of bone removed by osteoclasts should be replaced by osteoblastic activity

Question 7

Name the mediators (hormones) involved in bone turnover

Answer 7

PTH/PTHrP
1,25 dihydroxyvitamin D
Oestrogen, testosterone
Cortisol
GH, IGF-1
Leptin, adiponectin

Question 8

Name the mediators (paracrine/autocrine) of bone turnover

Answer 8

Prostaglandins
Interleukin-1 (IL-1), interleukin- (IL-6)
Tumour necrosis factor (TNF)

Question 9

What is bone resorption a balance between

Answer 9

RANK ligand and OPG

RANK ligand - promotes osteoclast activation
OPG - prevents osteoclast activation