Regulation Of Bone Remodelling Flashcards
Why does bone turn over
Repair micro damage
Respond to mechanical stimuli
Store and release mineral
What is modelling
Gross shape is altered, bone is added or taken away
What is remodelling
All of the bone is altered and new bone replaces old bone
What are osteoclasts
Specialised macrophages
Describe the bone remodelling cycle
Signal from bone for repair
Response to signal osteoclasts attach to bone lining
Resorption cavities are formed
Osteoblasts are signalled to attach to resorption cavities and secret osteoid
Osteoid is mineralised
New bone is formed
What are the mediators of bone turnover
Hormones including
PTH
1,25 dihydroxyvitamin D
Oestrogen, testosterone
Cortisol
GH, IGF-1
Leptin and adiponectin
Paracrine/autocrine(local) including
Prostaglandins
Interleukin-1
TNF
What is the function of RANKL
Stimulates osteoclast differentiation and increases resorption activity
What secretes RANKL
Osteoblasts
What is the function of OPG
Inhibits oststeoclast differentiation and activity
What is denosumab
Monoclonal antibody to RANKL and is a treatment for osteoporosis
Where does sclerostin come from
It is a secreted protein from osteocytes
What influences bone tunover
Loading
Hormones
Cytokines
What are the regulators of turnover and are therapeutic targets
RANKL
Sclerostin
