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Bones and Skeletal Tissue

Bones and Skeletal Tissue. Chapter 6. Objectives. Know the functions of the skeletal system Understand how bones are classified Identify the macroscopic and microscopic features of bone Understand how bone is developed Know what a fracture is and how it is repaired

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Bones and Skeletal Tissue

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  1. Bones and Skeletal Tissue Chapter 6

  2. Objectives • Know the functions of the skeletal system • Understand how bones are classified • Identify the macroscopic and microscopic features of bone • Understand how bone is developed • Know what a fracture is and how it is repaired • Know some bone disorders

  3. Skeletal System • Composed of bones, cartilages, and ligaments joined tightly together to form a strong, flexible framework for the body • Skeleton functions • Support • Protection • Movement • Electrolyte balance • Acid-base balance • Blood formation • Osseous tissue • Connective tissue with a hardened matrix • Deposition of calcium phosphate and other minerals • Part of the composition of a bone http://www.amersol.edu.pe/class09/_09pdelaf/7th/science/webpages/skeleton.html

  4. Classification of Bones • Classified based on shape and corresponding function • Four categories • Long bones • Short bones • Irregular bones • Flat bones massasoit-bio.net

  5. General Features of Bones • Epiphysis • Ends of the bone • Composed of cancellous (spongy) bone • Diaphysis • Shaft of the bone • Composed of compact bone • Medullary cavity • Contains yellow bone marrow • Epiphyiseal plate http://pathologyoutlines.com/bone.html

  6. Structure of Bone Figure 5.1

  7. Histology • Four main types of bone cells • Osteogenic (osteoprogenitor) cells • give rise to osteoblasts , osteocytes • Osteoblasts • Bone-forming cells • Found along endosteum and periosteum • Secrete osteocalcin • Osteocytes • Former osteoblasts that have been trapped in their lacunae • Maintain bony matrix • Strain sensors • Octeoclasts • Bone-dissolving cells • Matrix • composed of inorganic and organic components • Inorganic component • Hydroxyapaptite • Composed mainly of CaPO4 salt • Organic components • Protein and carbohydrate • Collagen • Bone is a composite

  8. Compact Bone • Osteon (haversian system) • Basic structural unit of compact bone • Central (haversian) canal surrounded by concentric lamellae (matrix) • Perforating canals • Transverse or diagonal passages into the central canal • Originate at nutrient foramen ask.com

  9. Spongy Bone • Composed by a network of trabeculae • Spaces filled with red marrow • Beams arranged to sustain stress commons.wikimedia.org

  10. Bone Development • Ossification or osteogenesis • Formation of bone • Two methods • Intramembranous ossification • Endochondral ossification

  11. Intramembranous Ossification • Produces flat bones of skull and clavicles • Starts with osteoid • End with diploe massasoit-bio.net

  12. Endochondral Ossification • Bone develops from a hyaline model trjohn.blogspot.com

  13. Bone Growth and Remodeling • Bone Elongation • Involves epiphyseal plates • Hyaline cartilage between to transitional zones (metaphysis) • Zones of mataphysis • Reserve cartilage • Cell proliferation • Cell hypertrophy • Calcification • Bone deposition • Spongy bone nzdl.org

  14. Bone Growth and Remodeling • Interstitial growth • Result from growth of cartilage within the metaphysis • Finite process • Epiphyseal line • Appositional growth • Growth in diameter and thickness • Circumferential lamellae • Remodeling • Wolff’s law of bone • The architecture of bone is determined by the mechanical stresses placed up it. • Bone adapts to withstand stress

  15. Physiology of Osseous Tissue • Mineral deposition • Calcium and phosphate are allowed to reach their solubility product • Precipitate in the matrix • Ectopic ossification • Abnormal calcification of soft tissue • Calculus • Mineral resorption • HCl secreted by osteoclasts • Acid phosphatase • Absorbs collagen

  16. Fractures and Repair • Fracture • Break in the bone • Two types • Stress • Pathological • See table 6-2 • Granulation tissue • Fibrous mass of capillaries and cells within hematoma medical-definitions.com

  17. Bone Disorders • Osteoporosis • Sever loss of bone density • Osteoclast more active than osteoblasts • Osteosarcoma • Most common and deadly form of bone cancer • Metastasizes quickly • Osteogenesisimperfecta • Brittle bones • Defect in collagen deposition

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