Bone Flashcards
Composition of bone
cells: osetoblast/clast / cyte osteoid 95% type 1 collagen 5%- groubd substance-proteoglycan mineral crystalline hydroxyapetiteq
lengthening of bone vs widening
L: at epiphyseal late
W: bone matrix on outer shaft and resoprtion on inner part
what increases chondrocyte growth
IGF1
FGF2
TGF BETA
BMP?
Bone morphonegentic protein
induce hypertrophy and differentiation of chondrocytes
systemic hormones
thyroid an vitamin D: INDUCE HYPERTROPHY
Explain Bone remodeling
orgination of BMU Osteoclast recruitment resorption osteoblast osteoid mineralization Quiescence
Orgination of bmu
lining cells are activated by PTH , growth factors anf local cytokines
osteoclast recruitment
M-CSF induce RANK expression
RANK Ligand will bind but can be inhibited by OPG
OPG
Osteogrotegrin
bone remodeling : resorption .
Acid and digestive enzymes are secreted into sealed space.
Integrins, interleukins and vitamin A stimulate resorption.
Decreased estrogen delays apoptosis of osteoclasts.
bone remodeling: Osteoblast recruitment
attached to BMU by TGF Beta , BMP and IGF
cbfa-1 increases osteoblast
bone remodeling: Osteoid
Osteoid (bone matrix) formation
Osteoid is made by osteoblasts in layers
bone remodeling :mineralization
Mineralization is initiated when the osteoid reaches a thickness of approximately six Fm.
bone remodeling :Quiescence
G. Quiescence
As bone is completed osteoblasts are converted to osteocytes or lining cells and their metabolic rate declines.
osteoporosis
a disease characterized by low bone mass and microarchitectural deterioration of bone tissue, leading to enhanced bone fragility and a consequent increase in fracture risk
