Bones

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Types of bones and bone cycle

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Bones

  1. 1. Chapter 6: Osseous Tissue and Bone Structure
  2. 2. The Skeletal System <ul><li>Skeletal system includes: </li></ul><ul><ul><li>bones of the skeleton </li></ul></ul><ul><ul><li>cartilages, ligaments, and connective tissues </li></ul></ul>
  3. 3. Functions of the Skeletal System <ul><li>Support </li></ul><ul><li>Storage of minerals (calcium) </li></ul><ul><li>Storage of lipids ( yellow marrow ) </li></ul><ul><li>Blood cell production ( red marrow ) </li></ul><ul><li>Protection </li></ul><ul><li>Leverage (force of motion) </li></ul>
  4. 4. Bone Shapes <ul><li>Long bones </li></ul><ul><li>Flat bones </li></ul><ul><li>Sutural bones </li></ul><ul><li>Irregular bones </li></ul><ul><li>Short bones </li></ul><ul><li>Sesamoid bones </li></ul>
  5. 5. Long Bones <ul><li>Are long and thin </li></ul><ul><li>Are found in arms, legs, hands, feet, fingers, and toes </li></ul>Figure 6–1a
  6. 6. Flat Bones <ul><li>Are thin with parallel surfaces </li></ul><ul><li>Are found in the skull, sternum, ribs, and scapula </li></ul>
  7. 7. Sutural Bones <ul><li>Are small, irregular bones </li></ul><ul><li>Are found between the flat bones of the skull </li></ul>
  8. 8. Irregular Bones <ul><li>Have complex shapes </li></ul><ul><li>Examples: </li></ul><ul><ul><li>spinal vertebrae </li></ul></ul><ul><ul><li>pelvic bones </li></ul></ul>
  9. 9. Short Bones <ul><li>Are small and thick </li></ul><ul><li>Examples: </li></ul><ul><ul><li>ankle </li></ul></ul><ul><ul><li>wrist bones </li></ul></ul>
  10. 10. Sesamoid Bones <ul><li>Are small and flat </li></ul><ul><li>Develop inside tendons near joints of knees, hands, and feet </li></ul>
  11. 11. Bone Markings <ul><li>Depressions or grooves: </li></ul><ul><ul><li>along bone surface </li></ul></ul><ul><li>Projections: </li></ul><ul><ul><li>where tendons and ligaments attach </li></ul></ul><ul><ul><li>at articulations with other bones </li></ul></ul><ul><li>Tunnels: </li></ul><ul><ul><li>where blood and nerves enter bone </li></ul></ul>
  12. 12. Bone Markings Table 6–1 (1 of 2)
  13. 13. Bone Markings Table 6–1 (2 of 2)
  14. 14. Characteristics of Bone Tissue <ul><li>Periosteum: </li></ul><ul><ul><li>covers outer surfaces of bones </li></ul></ul><ul><ul><li>consist of outer fibrous and inner cellular layers </li></ul></ul><ul><li>Dense matrix, containing: </li></ul><ul><ul><li>deposits of calcium salts </li></ul></ul><ul><ul><li>bone cells within lacunae organized around blood vessels </li></ul></ul><ul><li>Canaliculi: </li></ul><ul><ul><li>form pathways for blood vessels </li></ul></ul><ul><ul><li>exchange nutrients and wastes </li></ul></ul>
  15. 15. Long Bones <ul><li>Diaphysis: </li></ul><ul><ul><li>the shaft </li></ul></ul><ul><li>Epiphysis: </li></ul><ul><ul><li>wide part at each end </li></ul></ul><ul><ul><li>articulation with other bones </li></ul></ul><ul><li>Metaphysis: </li></ul><ul><ul><li>where diaphysis and epiphysis meet </li></ul></ul>
  16. 16. Flat Bones <ul><li>Resembles a sandwich of spongy bone </li></ul><ul><li>Between 2 layers of compact bone </li></ul>
  17. 17. Compact Bone Figure 6–5 The osteon is The basic unit of mature compact bone Osteocytes are arranged in concentric lamellae Around a central canal (Haversian canal) containing blood vessels
  18. 18. Spongy Bone <ul><li>Does not have osteons </li></ul><ul><li>The matrix forms an open network of trabeculae </li></ul><ul><li>Trabeculae have no blood vessels </li></ul>Figure 6–6
  19. 19. Red Marrow <ul><li>The space between trabeculae is filled with red bone marrow : </li></ul><ul><ul><li>which has blood vessels </li></ul></ul><ul><ul><li>forms red blood cells </li></ul></ul><ul><ul><li>and supplies nutrients to osteocytes </li></ul></ul>
  20. 20. Yellow Marrow <ul><li>In some bones, spongy bone holds yellow bone marrow: </li></ul><ul><ul><li>is yellow because it stores fat </li></ul></ul>
  21. 21. Bone Cells <ul><li>Make up only 2% of bone mass: </li></ul><ul><ul><li>osteocytes </li></ul></ul><ul><ul><li>osteoblasts </li></ul></ul><ul><ul><li>osteoprogenitor cells </li></ul></ul><ul><ul><li>osteoclasts </li></ul></ul>
  22. 22. Osteoblasts <ul><li>Immature bone cells that secrete matrix compounds (Make new bone) </li></ul>Figure 6–3 (2 of 4)
  23. 23. Osteocytes <ul><li>Mature bone cells that maintain the bone matrix </li></ul><ul><li>Are between layers (lamellae) of matrix </li></ul><ul><li>Connect by canaliculi in lamellae </li></ul><ul><li>Do not divide </li></ul>Figure 6–3 (1 of 4)
  24. 24. Osteocyte Functions <ul><li>To maintain protein and mineral content of matrix </li></ul><ul><li>To help repair damaged bone by turning into osteoblasts. </li></ul>
  25. 25. Osteoprogenitor Cells <ul><li>Stem cells that divide to produce osteoblasts </li></ul><ul><li>Are located in inner, cellular layer of periosteum (endosteum) </li></ul>Figure 6–3 (3 of 4)
  26. 26. Osteoclasts <ul><li>Secrete acids and protein-digesting enzymes to dissolve old bone matrix in a process called osteolysis </li></ul>Figure 6–3 (4 of 4)
  27. 27. Homeostasis <ul><li>Bone building (by osteoblasts) and bone recycling (by osteoclasts) must balance: </li></ul><ul><ul><li>more breakdown than building, bones become weak </li></ul></ul><ul><ul><li>exercise causes osteoblasts to build more bone </li></ul></ul><ul><ul><li>Lack of exercise causes bone loss </li></ul></ul>

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