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Ch 5 Skeletal System

Ch 5 Skeletal System. Bone Tissue. Connective tissue with a matrix hardened by minerals (calcium phosphate) Continually remodels itself Functions of the skeletal system support, protection, movement, mineral storage, blood formation (hematopoiesis). Shapes of Bones.

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Ch 5 Skeletal System

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  1. Ch 5 Skeletal System

  2. Bone Tissue • Connective tissue with a matrix hardened by minerals (calcium phosphate) • Continually remodels itself • Functions of the skeletal system • support, • protection, • movement, • mineral storage, • blood formation (hematopoiesis)

  3. Shapes of Bones • Long bones – levers acted upon by muscles • Short bones – glide across one another in multiple directions • Flat bones – protect soft organs

  4. Types of bone tissue • Compact – dense, made of osteons • Spongy – porous, made of irregular, needle like trabeculae

  5. Structure of a Long Bone • Shaft (diaphysis) • Enlarged ends (epiphyses) • Epiphyseal plate (growth plate > line) • Compact and spongy bone • Marrow cavity • Articular cartilage • Periosteum • Endosteum

  6. Structure of a Flat Bone • External and internal surfaces composed of compact bone • Middle layer is spongy bone and bone marrow

  7. Compact Bone • Osteon = basic structural unit • cylinders formed from layers (lamellae) of matrix around central canal (Haversion canal) • osteocytes in lacunae connected to each other and their blood supply by tiny cell processes in canaliculi

  8. Blood Vessels of Bone • Perforating canals or Volkmann canals - perpendicularly join central canals

  9. Bone Cells • Osteoblasts form organic matter of matrix • Osteocytes are osteoblasts trapped in the matrix they formed • cells in lacunae connected by gap junctions inside canaliculi

  10. Bone Cells • Osteoclasts develop in bone marrow by fusion of 3-50 stem cells • Reside in pits that they ate into the bone • Resorb (break down) bone matrix

  11. Matrix of Bone Tissue • Dry weight = 1/3 organic & 2/3 inorganic matter • Organic matter • Collagen and glycoproteins • Inorganic matter • 85% hydroxyapatite Ca10(PO4)6(OH)2 • 10% calcium carbonate   CaCO3 • other minerals (fluoride, potassium, magnesium) • Combination provides strength and resilience

  12. Spongy Bone • Spongelike appearance formed by plates of bone called trabeculae • spaces filled with red bone marrow • Trabeculae have few osteons or central canals • no osteocyte is far from blood of bone marrow • Provides strength with little weight • trabeculae develop along bone’s lines of stress

  13. Spongy Bone Structure and Stress

  14. Bone Marrow • In medullary cavity (long bone) and among trabeculae (spongy bone) • Red marrow like thick blood • reticular fibers and immature cells • Hemopoietic (produces blood cells) • in vertebrae, ribs, sternum, pelvic girdle and proximal heads of femur and humerus in adults • Yellow marrow • fatty marrow of long bones in adults

  15. Bone marrow transplant

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