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15 Cards in this Set
- Front
- Back
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Bone
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- mineralized ECM
- support, protection, and storage (of calcium) - Matrix - Osteocytes |
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Bone Matrix
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- collagen I and V (mostly type I)
- GAGs (glycoaminoglycans- provide support for bones- compression) - other proteins like PDGF and BMP |
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Cells present in bone
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Osteocytes:
- lacunae and canaliculi (canals) - osteoprogenitor cells --> osteoblasts (start secreting ECM) --> osteocytes (surrounded by matrix) - bone lining cells (on bone sufaces) - osteoclasts (bone reabsorption) - Hydroxyapatite- gives bone its rigidity |
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Classification of Bone:
- Types of tissue - Types of bones |
* Two types of tissue:
1. Compact (dense)- on outside 2. Spongy (cancellous- on inner area; bone marrow here) * Types of Bones: - long bone (ex: femur) - short bone (ex: wrist bones) - flat bone (ex: skull) - irregular bone (ex: vertebral column) |
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Long Bone
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* Regions:
- Epiphysis- end - Metaphysis- flaring out region - Diaphysis- long shaft part (mostly compact bone) |
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Structural components of bone
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- periosteum- outer layer on outside of bone.
Layers: 1. Outer layer- high collagen concentration 2. Inner layer- progenitor cells (make bone) - endosteum- similar lining on inner side and also lines the canals - marrow- in the cavities of spongy bone (developing RBC found here) |
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Marrow
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Red = marrow involved in making RBC (only in certain regions in adults)
Yellow = inactive in making RBCs, so has higher portions of fats |
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Osteocytes
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- cells imbedded in bone and produce ECM
- live singularly inside lacunae - cells communicate by diffusion thru canaliculi |
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Mature Bone has...
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- osteons (spiraling circles)
- concentric lamellae - osteonal canal (Haversian system- where blood vessels go through) - interstitial lamellae - circumferential canals - perforating canals - caniculi - Volkmann (or perforating) canals- connect one osteonal canal to another |
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Bone Cell Types
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From Mesenchyme cells:
1. Osteoprogenitors- on outside of bone 2. Osteoblasts- (osteoprogenitors differentiate to form these) located on growing bone 3. Bone Lining Cells- cells that remain on the surface 4. Osteocytes- surrounded by ECM (embedded) separate: 5. Osteoclasts- involved in bone reabsorption |
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Bone Cells
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* Osteogenitor cells- periosteal and endosteal
* Osteoblasts- produce ECM |
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Osteocyte Stages
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- Quiescent: mature bone
- Formative: actively producing matrix (more machinery is present) - Resorptive: bone being reabsorbed (lysosomes more abundant) |
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Bone-Lining Cells
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- supportive surface cell that helps osteocytes
- derived from osteoblasts - periosteal or endosteal cells |
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Osteoclasts
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- large, multinucleate cells that are involved in bone reabsorption/remodeling
- resorption bay- ability to reabsorb bone - ruffled border and clear zone |
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Bone Formation methods
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2 methods:
1. Intramembranous Ossification- mesenchyme cells to osteoblasts; seen in flat bones and peripheral long/short bones 2. Endochondral Ossification- produce cartilagenous skeleton first and then replace to bone (hyaline cartilage model replaced with bone) |
