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36 Cards in this Set
- Front
- Back
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Bone - roles
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specialized CT
storage site for Ca and PO4 homeostasis of blood Ca |
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Bone - components
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cells and ECM
ECM mineralized, support/protection mineral is hydroxyapatite |
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Proteins of bone matrix
Collagen |
90% type I
some V, trace II, XI, XIII |
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Proteins of bone matrix
Non-collagenous |
Proteoglycans
Multiadhesive proteins Bone specific vitamin K dependent proteins Growth factors/cytokines |
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Non-collagenous proteins
Proteoglycans |
compressive strength
bind growth factors inhibit mineralization |
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Non-collagenous proteins
Multiadhesive proteins |
attach bone cells and collagen fibers to ground substance
osteonectin: attaches collagen and hydroxyapatite sialoproteins: mediate attachment, initiate CaPO4 formation during crystallization |
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Non-collagenous proteins
Bone specific Vitamin K dependent proteins |
osteocalcin: recruits serum Ca ions, activates osteoclasts
Protein S Matrix Gla-protein |
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Non-collagenous proteins
Growth factors/cytokines |
insulin like growth factors
tumor necrosis factor transforming factor platelet derived growth factor interleukins Bone morphologic proteins (BMPs) - induce differentiation of mesenchymal cells into osteoblasts |
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Lacunae
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osteocyte caves - interconnected via canaliculi (osteocyte processes) which allow contact between neighboring osteocytes/blasts
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Bone tissue components
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bone, hemopoietic, fat, BVs, nerves, hyaline cartilage
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Compact bone
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dense with lamellar structure
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spongy/cancellous bone
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formed of anastamosing trabeculae, spaces between trabeculae filled with marrow and BVs
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Long bones
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longer in one dimension
diaphysis - shaft epiphysis - end metaphysis - tapered region between epiphysis and diaphysis medullary cavity - in shaft, marrow filled space tibia, humerus, metacarpals |
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Short bones
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as long as wide
carpal bones of wrist |
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Flat bones
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Thin, platelike
thick compact layers sandwich spongy bone Calvaria (roof of skull), sternum |
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Irregular bones (junk drawer)
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Don't fit into other 3 categories
Vertebrae, ethmoid bone |
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Periosteal surface of bone
Periosteum |
1) outer fibrous layer
Collagen runs II to bone surface Sharpey's fibers - collagen embedded in bone, periosteal anchor 2) inner, cellular layer (osteoprogenitor cells) reduced in nonactively dividing bones collagen runs II to bone surface |
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Bone cavities
Endosteum |
Composed of osteoprogenitor cells, bone lining cells, osteoblasts
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Red marrow
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developing blood cells
reticular fibers and cells blood vessels |
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Yellow marrow
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fat cells
can revert to red marrow following injury or blood loss |
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Osteon components
Haversian canal |
contains BVs and nerves
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Osteon components
Interstitial lamellae |
located between osteons, remnants of old osteons
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Osteon components
Collagen orientation |
fibers run II within lamella, but perpendicular to fibers in adj lamallae
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Osteon components
Circumferential lamellae |
surround entire bone from peri to endosteum
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Osteon components
Volkman's/perforating canals |
Connect Haversian canals, run perpendicular to bone's long axis (not surrounded by concentric lamellae)
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Osteon components
Nutrient foramina |
Vessels enter bone here, located in epiphyses and diaphyses
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Mature spongy bone structure
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tissue arranged as trabeculae
marrow interconnects between trabeculae thicker trabeculae are osteon containing |
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Blood supply to bone
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Vessels enter through nutrient foramina in dia/epiphyses
metaphysial arteries veins leave nutrient foramina/venous drainage via periosteum lacking lymphatic vessels |
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Immature/woven bone
differs from mature bone. |
non lamellar
more cells/unit area than mature bone random arrangement of cells matrix has more ground substance less heavily mineralized more rapidly forming |
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Osteoprogenitor cells
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mesenchymal origin
transform into osteoblasts influenced by core binding factor alpha 1 found at periosteal and endosteal surfaces, osteonic and perforating canals |
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osteoprogenitor cell morphology
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flat
lightly staining elongate or ovid nuclei some rER, Golgi, free ribosomes |
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osteoblasts
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able to divide
secrete Type I collagen responsible for calcification of bone matrix via membrane vesicles |
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Osteoid (unmineralized matrix)
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non-collagenous bone matrix proteins
calcium binds: osteocalcin, osteonectin multiadhesive glycoproteins: bone sialoproteins Osteopontin, thrombospondin |
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Osteoblast vesicles
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membrane limited organelles
rich in alkaline phosphotase released only during matrix production |
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Osteoblast morphology
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polygonal or cuboidal, single layer on bone surface
atop layer of osteoid basophilic cytoplasm prominent Golgi, rER, free ribosomes PAS stained granules |
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Clinical markers of osteoblast activity
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serum alkaline phosphotase and osteocalcin
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