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describe pointing to an osteocyte in intramembranous ossification
little cells in the center w/canaliculi branches coming off.
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list 4 steps in Intramembranous ossification
- 1) mesenchyme> osteoblasts>
- 2) osteoblasts> osteocytes.
- 3) mesenchyme> periosteum forms
- 4) osteoblasts> compact bone.
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define Trabeculae
group of partitions formed by bands or columns of connective tissue
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step 1 in intramembranous ossificaton
*occurs on or in fibrous connective tissue
-mesenchyme cells cluster into soft tissue along blood vessels.
-become osteoblasts,
-and secrete osteoid tissue away from vessles.
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step 2 of intramembranous ossificaton
-When osteoid tissue is mineralized by calcium salts to harden the matrix,
-osteoblasts become trapped in own matrix, and become osteocytes.
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step 3 of intramembranous ossificaton
-Meanwhile, mesenchyme adjacent to developing bone condenses and forms fibrous periosteum,
-spongy bone becomes honeycomb of calcified trabeculae.
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step 4 intramembranous ossificaton
-osteoclasts absorb some trabeculae making medullary cavities,
-osteoblasts beneath the periosteum fill spaces between trabeculae to form compact bone.
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where does ossification occur
the ossification center/lacunea.
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name of canal that is diagonal passage in bone
perforating (Volkmann) canal.
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explain lamellae
onionlike concentric layers of lacunae connected by canaliculi.
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explain a haversian canal
a central canal in which lamelae are surrounding.
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define chondrycytes
cell that has secreted the matrix of cartilage and become embedded in it.
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List the 4 stages in endochondrial ossification
- 1) mesenchyme>osteoblasts
- 2) osteoblasts>osteocytes
- 3) mesenchyme to periosteum
- 4) periosteum to compact bone
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first stage in Endochondrial ossification
-mesenchume condenses into hyaline cartilage w/fibrous perichondrium
-pericondrium produces condrocytes and cartilage model grows
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second stage in Endochondrial ossification
-Pericondrium becomes periosteum when it stops producing chondrocytes and starts producing osteoblasts.
-Osteocytes deposite around the middle, and chondrocytes inflate and die forming calcified walls
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third stage in Endochondrial ossification
- Blood vessels penetrate ossification center.
-Osteoclasts dissolve calcified tissue to form primary cavity in diaphysis.
-Chondrocytes in the epiphysis enlarge and die creating a secondary ossification center, with one epiphysis lagging behind the other.
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fourth stage in Endochondrial ossification
-Epiphysis fills w/spongy bone throughout childhood. Epiphyseal plate continues to grow until gap closes around late teenage years.
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what is articulation
the degree of movement
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define osteoporosis, cause & treatment.
- def: brittle bones
- cause: bone reabsorption outweighs deposit
- treatment: exercise & good bone building diet between 20-40.
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name 3 degrees of motion & describe them
- 1) synarthrosis: immovable
- 2) amphiarthrosis: slightly movable
- 3) diarthrosis: freely movable
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