Bone Flashcards
Bone is ___% inorganic hydroxyappetite and _______% organic with ___% collagen and ____% non collagenous protein
67
33
28
5
What are the 4 main physiological role of bone?
1-Structural
2-Calcium homeostasis (9-10 mg/dL)
3-Reservoir for growth factors in tissue repair
4-Contains both hematopoietic and mesenchymal progenitor cells in bone marrow
What links haversian canals to link osteons?
volkmann canals
Calcitonin ____ blood Ca++ while parathyroid _____ blood Ca++
lowers, raises
What are the 3 units of compact bone?
1-Circumferential (outer ring of bone)
2-Concentric lamellae (intact osteons)
3-Interstitial lamellae (former concentric lamellae filling in between)
Concentric lamella form around haversian canals forming a cylindrical structure called what?
Osteon
*basic functional unit of compact bone
Found at the ends of long bones, what type of bone provides structure in marrow spaces?
Cancellous bone (spongy/trabecular)
The connective tissue layer attached to the outer surface of a bone by sharpeys fibers is called?
Periosteum
*has two layers, outer fibrous and inner highly cellular/vascularized
Loose connective tissue covering the inner surface of both cancellous and compact bone is called?
Endosteum
Which bone cells are of mesenchymal origin?
Osteoblasts and Osteocytes (trapped osteoblasts)
Which bone cell is of hematopoietic origin?
Osteoclast
Which bone cells are mono nucleated, synthesize osteoid, arise from mesenchyme in response to a cascade of growth factors, and communicate with one another through gap junctions?
Osteoblasts
*secrete growth factors into osteoid matrix
Which bone cells are large, multi-nucleated cells responsible for resorption and are marked by Tartrate Resistant acid phosphatase?
Osteoclasts
What activates Osteoclast differentiation?
IL-1B and TNF-a
What do osteoclasts form in order to secrete hydrogen ions and matrix degrading enzymes and transcytose broken down products?
Howships Lacunae make by the ruffled border
*lamina limitans is the zone between the howships lacunae and intact bone
What system is used to regulate osteoblast and osteoclast function?
RANK-RANKL-OPG system
Which cells express RANKL?
Osteoblasts
Which cells express RANK?
Osteoclasts
What ligand is produced by osteoblasts to link RANKL as a competitive antagonist to RANK?
OPG (Osteoprotegerin)
What bone formation process starts with a hyaline cartilage pattern followed by mesenchymal cells condensing into chondrocytes into which collagen is secreted, mineralized and penetrated by vasculature?
Endochondral formation (typically long bones)
*Vasculature brings osteoblasts which start forming bone matrix
What structure make up the primary spongiosa and are bone matrix surrounding mineralized cartilage?
Mixed Spicules
Where are the secondary growth centers of some long bones?
Growth plates or epiphyses
What bone formation process is mesenchymal cells condensing in fibrous CT, differentiating into osteoblasts and forming an ossification center?
Intramembranous formation
Woven bone is _____formed and is then remodeled into mature ______ bone with a collar of _______ bone around it
Rapidly, trabecular, cortical
