Name the four types of bone cells?
Osteoprogenitor cells
Osteoblasts
Osteocytes
Osteoclasts
Where are osteoclasts found and what is their function?
Found on sites of bone resorption
Function is to erode and remodel the bone
What cells are osteoclasts derived from?
Blood monocytes
What regulates osteoclastic activity?
Hormones act on osteocytes which regulate osteoclasts
What substances to osteoclasts release?
H+ - acidic environment to solubilise the bone matrix
Cl-
Cathepsin K protease - degrades the protein and collagen
What condition arises from ossification deficits?
Osteogenesis imperfecta (short stature, fragile bones)
What condition arises from mineralisation defecits?
Osteomalacia (adults)
Ricketts (children)
In intermembranous ossification what is the template?
Mesenchymal membranous template
What type of bones is formed via intermembranous ossification and give an example?
Flat bones
Skull/clavicle/mandible
In endochondral ossification what is the template?
Hyaline cartilage
What forms the hyaline cartilage?
Mesenchymal cells
Define Wolf’s law?
Bone of a healthy person will adapt to loads under which it is placed
What is the cause of giganticism and acromegly and what is the difference between the two?
Pituarty gland tumour resulting in exccessive production of growth hormone, difference is giaganticism is in children and acromegly is in adults
Name the hormone that stimulates osteoclastic activity?
RANKL
Name the hormone that inhibits osteoclastic activity?
OPG
