Lecture 2-3.5 Intramembranous and Endochondrial ossification

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Lecture 2-3.5 Intramembranous and Endochondrial ossification
2015-11-13 23:57:48
Lecture Intramembranous Endochondrial ossification
Lecture 2-3.5 Intramembranous and Endochondrial ossification
Lecture 2-3.5 Intramembranous and Endochondrial ossification
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  1. describe pointing to an osteocyte in intramembranous ossification
    little cells in the center w/canaliculi branches coming off.
  2. list 4 steps in Intramembranous ossification
    • 1) mesenchyme> osteoblasts>
    • 2) osteoblasts> osteocytes.
    • 3) mesenchyme> periosteum forms
    • 4) osteoblasts> compact bone.
  3. define Trabeculae
    group of partitions formed by bands or columns of connective tissue
  4. 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.
  5. 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.
  6. step 3 of intramembranous ossificaton
    -Meanwhile, mesenchyme adjacent to developing bone condenses and forms fibrous periosteum,

    -spongy bone becomes honeycomb of calcified trabeculae.
  7. step 4 intramembranous ossificaton
    -osteoclasts absorb some trabeculae making medullary cavities,

    -osteoblasts beneath the periosteum fill spaces between trabeculae to form compact bone.
  8. where does ossification occur
    the ossification center/lacunea.
  9. name of canal that is diagonal passage in bone
    perforating (Volkmann) canal.
  10. explain lamellae
    onionlike concentric layers of lacunae connected by canaliculi.
  11. explain a haversian canal
    a central canal in which lamelae are surrounding.
  12. define chondrycytes
    cell that has secreted the matrix of cartilage and become embedded in it.
  13. List the 4 stages in endochondrial ossification
    • 1) mesenchyme>osteoblasts
    • 2) osteoblasts>osteocytes
    • 3) mesenchyme to periosteum
    • 4) periosteum to compact bone
  14. first stage in Endochondrial ossification
    -mesenchume condenses into hyaline cartilage w/fibrous perichondrium

    -pericondrium produces condrocytes and cartilage model grows
  15. 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
  16. 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.
  17. fourth stage in Endochondrial ossification
    -Epiphysis fills w/spongy bone throughout childhood. Epiphyseal plate continues to grow until gap closes around late teenage years.
  18. what is articulation
    the degree of movement
  19. define osteoporosis, cause & treatment.
    • def: brittle bones
    • cause: bone reabsorption outweighs deposit
    • treatment: exercise & good bone building diet between 20-40.
  20. name 3 degrees of motion & describe them
    • 1) synarthrosis: immovable
    • 2) amphiarthrosis: slightly movable
    • 3) diarthrosis: freely movable