Chapter 60 - Bone and Joint Biology Flashcards
collagen types found in bone
90% type I collagen
5% type III and IV
what i the primary extracellular matrix protein found in bone?
Type I collagen
what is the progenitor cell for osteoblasts
mesenchymal stem cells
what receptors do osteoblasts have on them?
PTH receptors
what substance do osteoblasts secrete?
type I collagen
what are marker proteins for osteoblasts?
alkaline phosphatase, osteocalcin, osteonectin, osteopontin
osteocyte role
support/maintainbone
signalling between osteocytes is mediated via
gap junctions
osteocyte role in bone remodeling
secrete RANK-L
load sensing, mechanosensing cells
how do osteocytes regulate bone formation
secrete sclerostin which acts on the Wnt pathway by binding LRP5/6 receptors on osteoblasts
progenitor cell for osteoclasts?
monocyte/macrophages (hematopoietic cells)
what are the repair stages of bone?
- inflammatory - macrophages infiltrate fracture site
- PDGF, TGFb, IL1, IL6, PGE2, TNFa released locally - early post fracture period
- periosteal pre-osteoblasts and local osteoblasts form new bone
- MSCs and fibroblasts proliferate
- BMPs and TGFs expressed - Fracture hematoma maturation
- neovascularization, MSC differentiation, cartilage formation (endochondral ossification) - Conversion of hypertrophic cartilage to bone
Collagen I, V, XI
osteocalcin
BMP, TGFB, IGF - Remodeling
synovial fluid composition
ultrafiltrate of plasma, low albumin concentration, high concentration of hyaluronic acid and lubricin
marker proteins for osteoclasts
tartrate resistant acid phosphatase (TRAP)
calcitonin receptor
cathepsin K
motion at a fracture site promotes what kind of secondary bone healing ossification?
endochondral ossification - callous formation - cartilage precursor
