rigid system of levers, production of soft viscera, storage depot for Ca and P, and houses hemopoetic tissue
What are the functions of bony skeleton?
osteoid, matrix vesicles, cytokines and growth factors
What do active osteoblasts synthesize and secrete?
matrix vesicles (alkaline phosphatase and other enzymes)
What are needed for calcification of matrix?
What are surrounded by bone ECM and have numerous cytoplasmic processes such as communication, metabolic exchange, and gap junctions?
maintain matrix through production and resporption, Ca exchange, and respond to changes in mechanical forces
What are the functions of osteoclasts?
enzyme secretion, proton pumps to form an acidic environment, and degrade bone matrix
What are the functions of osteoclasts?
What part of the ECM is 95% type I collagen fibers, layered parallel within a layer but alternating directions between layers?
The organic matrix has ___ such as GAGs like CS and KS and ____ such as osteonectin and osteocalcin.
tissue hydration, regulate fiber formation and mineralization, and cell / matrix interactions (metabolism and organization)
What are the functions of PGs and GPs in the organic bone ECM?
enzymes, enzyme inhibitors, chemical signaling molecules
What are the "leftover" ingredients of the organic ECM?
What are plates along collagen fibers and surrounded by a hydration shell (fluid bound to crystals)?
remove organic and inorganic components (if minerals were non-crystalline bone would be less rigid)
What is the role of ECM components?
What type of bone is highly ordered, has layers, is mature / secondary, and replaces woven bone?
Compact lamellar bone
What type of bone has osteon (haversarian system) with a central canal housing blood vessels and nerves?
Outer and inner circumferential lamellae
What parts of compact lamellar bone do not need osteon structure because there are vessels on the surface and they have no central canal?
efficiency (transfer of metabolies and wastes) and strength of bone in multiple directions (from alternating angles, good for tension and torsion)
What is the significance of layered arrangement in lamellar bone?
Spongy lamellar bone
What has trabeculae with alternating layers of bone matrix and cells, cavities between trabeculae filled with highly vascularized bone marrow, and haversarian systems are infrequent?
Compared to lamellar bone, woven bone has _____ mineral content and _____ cell conentration.
inner osteogenic layer
What part of the periosteum contains osteoprogenitor cells? These can differentiate to osteoblasts and chondroblasts.
Perforating (Sharpey's) fibers
What are collagen fibers that bind periosteum to bone and are numerous at tendon and ligament attachments?
intramembranous and endochondral ossification
What are the two pathways from initial mesenchyme primordium to bone?
The only difference between ossification in bone developed from a membranous model and in bone developed from a cartilaginous model is the ______ in which ossification occurs.
Through what ossification type does the development of flat bone occur?
sheets of mesenchyme
In flat bones the development of primary ossification centers occurs within what?
highly vascularized and differentiation of cells to osteogenic cells to osteoblasts
In the primary ossification center of flat bones, what is important?
After plates are formed cells become ______. Some cells on surface become additional ____ and process continues.
capillaries, bone marrow cells, undifferentiated cells
Spaces between plates and spicules contain what?
some areas spaces fill in > compact bone, others are cancellous bone
What happens with thickening of bony spicules?
Development of ossification centers, formation of plates / spicules, spaces between plates, additional ossification centers form, thickening of plates, and remodeling
What are the 6 steps in development of flat bones?
Part of long bone development where bone forms under periosteum and the periosteal band (bony collar) is formed?
Part of long bone ossification where remainder of long bone is formed and bone replaces hyaline cartilage?
hypertrophy, resorb matrix, degenerate
Within the bony collar during endochondral ossification condrocytes do what? Also calcification of residual matrix occurs.
periosteal (osteogenic) bud
Where osteoclasts penetrate bony collar and blood vessels grow and osteogenic cells migrate into opening created by osteoclasts?
This process occurs in the primary ossification center and is a combo or resorption and formation, increased density of bone along outer margin, and formation of marrow cavity.
epiphyseal cartilage plate
This is the cartilage between primary and secondary ossification centers where most of the growth in length of long bones occurs.
Zone of cell proliferation
What zone of the long bone has expansion of cartilage and increases length?
Zone of hypertrophic cartilage
What is the long bone zone where cartilage matrix is resorbed, cells accumulate glycogen, there is some addition to overall length, and a thin septa of matrix remain?
Zone of cartilage calcification
What is the long bone zone where remaining cartilage matrix is calcified, calcium and alkaline phosphate, and chondrocyte apoptosis?
Zone of ossification
What is the long bone zone where much of cartilage matrix and cells are removed, capillaries invade, osteoblasts deposit osteoid over calcified cartilage, and there is ossification of osteoid?
Where is there layers of osteons added from outside inward and central canal size decreases?
This incomplete calcification of bone occurs in chilren where bone is easily deformed and there is a decreased rate of bone growth.
This incomplete calcification of bone occurs in adults where deficient calcification of newly formed bone occurs, partial decalcification of older matrix, and decreased Ca per unit of bone matrix.
What are used to treat RA and enhance removal of bone and decrease action of osteoblasts?