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Unformatted text preview: Chapter 6: Bones and The Skeletal System
Bonnie S. Gunn Bones and cartilage of the Skeletal system What is cartilage? Skeletal cartilage is primarily water No nerves, no blood vessels Surrounded by perichondrium (source of blood vessels supplying nutrients via diffusion) Functions in support and protection, cushioning shock between bones and connecting tissues together Growth of cartilage Hyaline Elastic Fibrocartilage Two types of growth Appositional: new matrix secreted against external face of existing cartilage Interstitial: Chondrocytes divide and secrete new matrix, expanding from within Bone Tissue Dynamic tissue that continually remodels itself Bones and bone tissue bone or osseous tissue is a connective tissue with a matrix hardened by minerals (calcium phosphate) bones make up the skeletal system individual bones are made up of bone tissue, marrow, cartilage & periosteum Functions of the skeletal system support, protection, movement, blood formation, mineral reservoir, pH balance & detoxification Shapes of Bones Structure of a Flat Bone External and internal surfaces of flat bone are composed of compact bone Middle layer is spongy bone (diploe). No marrow cavity Blow to the skull may fracture outer layer and crush diploe, but not harm inner compact bone Structure of a Long Bone Periosteum & articular cartilage Compact & spongy bone Endosteum Yellow marrow General Features of Bones Shaft (diaphysis) is cylinder of compact bone containing marrow cavity (medullary cavity) & lined with endosteum (cells providing bone resorption & deposition) Enlarged ends (epiphyses) are spongy bone covered with a layer of compact bone enlarged to strengthen joint & provide for attachment of tendons and ligaments Joint surface covered with cartilage (lubrication) Remainder of bone covered with periosteum outer fibrous layer continuous with tendons perforating or Sharpey's fibers penetrate into bone matrix inner osteogenic layer important for growth & healing Epiphyseal plate or line depends on age Cells of Osseous Tissue Osteogenic cells reside in endosteum or periosteum multiply continuously & differentiate into osteoblasts Osteoblasts form organic matter of matrix & help to mineralize it in response to stress or fractures Osteocytes are osteoblasts that have become trapped reside in lacunae by are connected to each other via canaliculi signal osteoclasts & osteoblasts about mechanical stresses Cells of Osseous Tissue...
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