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16 Cards in this Set
- Front
- Back
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What are the 5 zones of endochondral ossification?
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1. Zone of reserve cartilage
2. Zone of proliferation 3. Zone of hypertrophy & calcification 4. Zone of retrogression & ossification 5. Zone of resorption |
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What do the cells look like in the zone of reserve cartilage?
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Chondrocytes are small & round & there is a large amount of matrix. This is normal cartilage.
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What do the cells look like in the zone of proliferation?
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Chondrocytes are flattened and arranged in column. They are being flattened because they are proliferating so there are a lot.
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What does the zone of hypertrophy and calcification look like?
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Chondrocytes are enlarged. Small aggregations of calcium phosphate deposits are present.
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What does the zone of retrogression and ossification look like?
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Chondrocytes dying. Osteoprogenitor cells are laying down bone matrix in the calcified cartilaginous matrix.
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What is the zone of resorption?
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Osteoclasts begin bone remodelling to accomodate the bone marrow. Osteoclasts resorb the bone matrix.
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What kind of bone replaces chondrocytes at ossification?
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Woven bone (not as strong)
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Which cells resorb the cartilaginous matrix when it is ossifying?
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Chondroclasts
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What is the difference between endochondral ossification and intramembranous ossification?
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Endochondral ossification needs cartilage as a precursor (long bones). Intramembranous ossification does not need cartilage (flat bones)
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Where do chondroblasts come from?
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They are differentiated from mesenchymal cells.
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What do chondroblasts secrete?
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Collagen matrix
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What is the cartilage model of bone made of? (before endochondral ossification begins)
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Hyaline cartilage: collagen type III, proteoglycans, hyaluronin
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How is bony collar formed from cartilage model of bone?
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Perichondreal cells stop producing chondroblasts and start producing osteoblasts
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What is osteoid?
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Unmineralized bone (collagen type I)
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What secretes osteoid?
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Osteoblasts
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When is osteoid secreted?
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During ossification
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