Bone Remodelling

Question 1

what are the 2 general types of bone?

Answer 1

cortical - compact
trabecular - spongy

Question 2

what cells are involved in bone remodelling

Answer 2

osteoblasts - bone formation
osteoclasts - bone resorption
osteocytes - embedded in bone matrix

Question 3

explain the general steps of resorption in bone remodelling

Answer 3

osteoclasts are recruited, they differenciate and activate to smooth out the surface of the impacted bone

Question 4

explain the general steps of reversal in bone remodelling

Answer 4

osteoclasts apoptose and are removed
osteoblasts are then recruited and they differenciate and become activated

Question 5

explain the general steps of formation in bone remodelling

Answer 5

after the matrix is synthesised, osteoblasts begin to lay down the new bone material in the space provided by the osteoclasts, the osteoblasts then become osteocytes

Question 6

explain the general steps of quiescence in bone remodelling

Answer 6

once the bone has been mineralised, a lining of cells forms over the orignially impacted area

Question 7

what molecule activates osteoblasts?

Answer 7

cbfa1

Question 8

explain the role of the RANK and OPG ligand in bone remodelling

Answer 8

RANK attaches to a RANK receptor on the osteoclast precursor activating it allowing it to mature
OPG inhibits RANK therefore inhibiting osteoclast activation

Question 9

name some of the stimulating systemic hormone modulators in bone remodelling

Answer 9

PTH
1,25 dihydroxyvitamin D
PTH-related protein
growth hormone
thyroid hormone

Question 10

name some of the stimulating locally acting factors in bone remodelling

Answer 10

Il-1, Il-6
tumour necrosis factor
insulin-like growth factor
prostoglandins

Question 11

name some of the inhibiting systemic hormone modulators in bone remodelling

Answer 11

estrogens
androgens
progestorone
calcitonin

Question 12

name some of the inhibiting locally acting factor modulators in bone remodelling

Answer 12

osteoprotegerin
mechanical loading
Il-4/10/13/18
growth factor beta

Question 13

explain how bone geometry changes with development

Answer 13

in spine - increased size and trabecular thickness
in long bones - increased length and diameter

Question 14

what are the 4 determinants of peak bone mass?

Answer 14

lifestyle, genetics, hormones, nutrition

Question 15

what are some of the biochemical markers of bone turnover?

Answer 15

bone matrix components - released in bloodstream during bone remodelling
enzymatic activity - specific to osteoblasts and osteoclasts