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Skeletal Tissues

This text discusses the structure and development of specialized connective tissues like bone and cartilage in the human skeletal system. It covers topics such as the arrangement of fibers, ground substance, mineralization, cell types, blood vessels, bone marrow, terminology, and the dynamic nature of bone.

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Skeletal Tissues

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  1. Skeletal Tissues Human Structure and Development ANHB 2212 Week 11 – 2006 Avinash Bharadwaj

  2. Specialised Connective Tissue • Better resistance to forces in various directions • Arrangement of fibres • Ground substance • Additional elements – mineral Bone • Resists compressionand shearing forces • Hard, mineralised • Limitations on cell metabolism  vascularity Cartilage • Resists compression(Compare fibrous tissue) • Firm

  3. Tissue Vs Organ • Bone as a tissue • Matrix – fibres, ground substance, calcium compounds as crystals • Cells – osteocytes, osteoblasts, osteoclasts • Blood vessels • Periosteum • Named bones as organs • Shell of bony tissue • Bone marrow • Red – blood forming • White (yellow) – adipose

  4. Terminology Gross anatomical • Types • Long • Short • Flat • Irregular • Parts (long bones) • Shaft (diaphysis) • Epiphysis • Metaphysis • Appearance • Compact • Cancellous (trabecular / spongy)

  5. Bone as a Connective Tissue • Bone forming cell – osteoblast. • Produces matrix around itself. • Calcium deposition – enzyme mediated. • Orderly deposition of microcrystals. • Similar to calcium hydroxyapatite. Ossification is not the same as calcification! • Hard matrix  lacuna. • Osteocytes – resting cells, maintenance. • Must never be too far from a blood vessel.

  6. And more… • Bone just before mineralisation – osteoid. • Newly formed bone • Irregular arrangement of collagen • Woven bone (Not to be confused with ‘cancellous’) • Mature bone (lamellar bone) • Sheets of matrix (lamellae) • Collagen fibres in a sheet – roughly parallel • Neighbouring sheets – different directions Compact bone, as seen in a t.s. of a long bone, is illustrative.

  7. Structure of Compact Bone • Mechanical principles • Tube versus column • Economy and strength • Multiple units • Built around blood supply • Shearing forces – both directions • Alternate layers • Direction of collagen fibres

  8. Terminology Again! • Periosteum and endosteum • Outer circumferential lamellae • Inner circumferential lamellae • Osteons (Haversian systems) • Haversian lamellae • Haversian canals • Transverse canals (Volkmann’s) Bone structure is built around blood vessels. Cancellous bone is also lamellar!

  9. Woven Lamellar

  10. The Cells of Bone • Osteoblast • Large cells, basophilic cytoplasm and large nuclei…(More later). • Osteocyte • Lacuna • Canaliculi – comunications between lacunae • Osteocyte processes in canaliculi • Osteoclast (“bone-breaker”) • Phagocytic • Giant multinucleated cells

  11. Bone – A Dynamic Tissue! • Growth – over a limited period. • Repair and maintenance. • Remodelling • During growth period • After injury and repair • In response to forces • Dynamic calcium reservoir • Hormonal control Osteoclasts (“bone-breakers”) are equally important!

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