Skeletal system: Bone tissue

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Skeletal system: Bone tissue
2012-06-27 16:41:13
Skeletal system Bone tissue

Skeletal system: Bone tissue
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  1. Functions of Bones: Support
    serves as the sturctural frame work for the body by supporting soft tissue and providing attachment points for the tendons of most skeletal muscles
  2. Functions of Bones: Protection
    • protects the most important internal organs from injury
  3. Functions of Bones: Assistance in movement
    most skeletal muscles attach to bones; when they contract they pull on bones to produce movement
  4. Functions of Bones: mineral homeostasis (storage and release)
    bone tissue stores several minerals, like calcium and phosphorus, which contribute to the strength of bone.  On demand, bone releases minerals into blood to maintain critical mineral balances and to distribute the minerals to other parts of the body
  5. Functions of Bones: Blood cell protection
    within certain bones a connective tissue called red bone marrow produces red blood cells, white blood cells, and plateletes, a process called Hemopoiesis
  6. Red bone marrow
    consists of developing blood cells, adipocytes, fibroblasts, macrophages within a network of reticular fibres
  7. Functions of Bones: Triglycerides storage
    Yellow bone marrow consists of mainly adipose cells, which store triglycerids.  The stored triglycerids are a potential chemical energy reserve.
  8. Structure of a long bone: Diaphysis
    is the bone's shaft or body - the long cylindrical main portion of the bone
  9. Structure of a long bone: Epiphysis
    are the proximal and distal portions of the bone
  10. Structure of a long bone: metaphysis
    • are the regions between the epiphysis and the diaphysis.  In a growing bone every metaphysis contains and epiphyseal growth plate.
  11. Structure of a long bone:Epiphyseal growth plate
    found in the metaphysis, it is a layer of hyaline cartillage that  allows the diaphysis of the bone to grow in length.
  12. Structure of a long bone: Articular cartilage
    • Is a thin layer of hyaline cartillage covering either end of the epiphysis where it forms a joint
    • Function: it reduces friction and absorbs schock 
  13. Structure of a long bone: Periosteum
    surrounds the external bone surface whereever it is not covered by the articular cartillage.

    Function: protects the bone, assists in fracture repair, helps nurrish bone tissue, and serves as an attachment point for tendons and ligaments 
  14. Structure of a long bone: medullary cavity
    is a hollow cylindrical space within the diaphysis that contains fatty yellow bone marrow
  15. Structure of a long bone: Endosteum
    lines the medullary cavity.  It contains a single layer of cells and a small amount of connective tissue
  16. Histology of bone tissue: Hydroxyapatite
    is a crystal formed from calcium phosphate and calcium hydroxide
  17. Histology of bone tissue: Calcification
    Mineral salts like Hydroxyapatite are deposited in the framework of collagen fibers of the extracellular matrix, they crystalize and the tissue hardens.  This process is initiated by bone building cells called osteoblasts.
  18. Histology of bone tissue: osteogenic cells
    are unspecialized stem cells derived from mesenchyme.  They are the only bone cells to undergo cell division.  The resulting cells are osteoblasts
  19. Histology of bone tissue: osteoblasts
    are bone building cells.  They synthesize and secrete collagen fibres and other organic components needed to build extracellular matrix of bone tissue and they intiate calcification
  20. Histology of bone tissue: Osteocytes
    mature bone cells formed after osteoblasts have surrounded themselves with extracellular matrix.  They maintain the bones daily metabolism, such as the exchange of nutrients and waste with the blood.  They do not undergo cell division
  21. Histology of bone tissue: Osteoclasts
    are huge cells derived from the fusion of as many as 50 monocytes and are concentrated in the endosteum.  Digest the underlying protein and mineral componenets of the extracellular matrix.
  22. Compact bone tissue
    contains few spaces and is the strongest form of bone tissue. It is found beneath the periosteum of all bones and makes up the bulk of the diaphysis of all bones. 
  23. Compact bone tissue: perforating canals
    Blood vessels, lympatic vessels, and nerves from the periosteum penetrate compact bone through these canals
  24. Compact bone tissue: central or haversion canals
    run longitudinally through the bone and are connected to the vessels and nerves of the perforating canals
  25. Compact bone tissue: concentric lamellae
    rings of calcified extracellular matrix much like the rings of a tree that surround the central canals
  26. Compact bone tissue: Lacunae
    between the lamellae are small spaces called lacunae, which contain osteocytes.
  27. Compact bone tissue: Canaliculi
    Radiating from around the osteocyte inside the lacunae are finger like canals filled with extracellular fluid. Inside these canals are finger like processes of osteocytes that connect neighbouring osteocytes with eachother and the central canals.
  28. Osteon and Haversian systems
    • Components of compact bone tissue are arranged into repeating structural units called osteons (or Haversian) units. 
    • -each one consists of a central canal, with concentrically arranged lamellae, lacunae, canaliculi and osteocytes.  
  29. Spongy bone tissue
    • does not contain osteons
    • -consists of lamellae arranged in an irregular lattice of thin columns called Trabeculae 
    • - It makes up most of the bone tissue of short, flat, and irregular shaped bones, and most of the epiphysis of of long bones.