Bone Flashcards
Bone composition
similar to dentin, HA overlaid on a collagen 1 scaffold
67% inorganic 33% organic (28 collagen and 5 noncollagen)
physiological role of bone
structural, calcium homeostasis, reservoir of growth factors,
macrostructure of bone
outer dense cortical bone with inner cavity
inner cavity has marrow
highly vascular
circumferential outer ring
concentric lamella- small rings- big outer convering
insterstitioal lammela- former concentric lamellae
Osteon
basic function of compact bone
form cylinders parallel to long axis of bone
haversian canal has blood vessel
volkmann canal connects haversian canals
cancellous bone
spongy bone
found at ends of long bones, in apposition to joints and associated with marrow spaces
structural support, highly vascularized
blood cell production
periosteum
CT layer on outer surface connected by sharpeys fibers
outer fibrous and inner (highly cellular and vascularized)
endosteum
loose CT covering in inner surface
seperates marrow from bone
osteoblasts
mononucleated cells which synthesize osteoid matrix
mesenchyme origin
differentiate in response to cascade of growth factors
formation and repair
communicate through gap junction
secrete matrix and grwoth factors
after formation flatten and form bone lining cells
osteocytes
osteoblasts embedded in matrix
form interconnected lacunar in bone tissue
ccellular processes which interact with surrounding bone tissue
possibly work in conjunction with bone lining cells
osteoclasts
large multinucleated- fusion from monocytes
resorption of bone
activated in inflammation
key marker: TRAP
attach to surface mediated by integrin, forms ruffled border
lamina limitans is demineralized bone zone between howships lacunae and intact bone
transcytosis of matrix components
control of bone formation
complex itneractions between osteoblasts and clasts
osteoblasts regulate osteoclasts function: RANK-RANKL-OPG
see slides
Endochondral Formation
formed from cartilage pattern
collagen broken down by chodoclasts allowing penetration of vasculature, mesenchymal cells differentiate to osteoblasts
bone matrix surrounds remaining minerlaized collagen froming primary spongiosa
osteoclasts gradually remove minerlaized cartilage and devvelop marrow cavity
secondary growth centers from epiphysis of long bones
intramembranous formation
mesenchymal cells condense in fibrous CT and differentiate to OB.
osteoid secreted then pentrated by vessels to make woven bone
remodled
sutural bone growth
fusion of skull plates, allow for brain to grow
inner cambian layer associated with periosteum and outer capsular layer
bone remodling and repair
consistantly being remodled
formed around periosteum while remodeled from marrow cavity (allows growth)
many factors control this
primary osteons replaced with secondary then tertiary ect
