BIOL&251Ch6NotesSpr11

BIOL&251Ch6NotesSpr11 - Ch. 6 Osseous (Bony) Tissue and...

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1 Ch. 6 – Osseous (Bony) Tissue and Bone Structure • Elements of the skeletal system : – The bones of the skeleton (~ 206 of them!) – Cartilages, ligaments, and other CTs that stabilize and connect the bones • Functions : – Physical/structural support Storage of minerals (calcium and phosphorus) and lipids/energy (in yellow marrow) Blood cell production (via hemopoiesis in red marrow) Protection (of soft internal body parts) Leverage for movement (via muscles pulling on bones) Fig. 6-1, p. 186 Bone shapes Long bones – have distinct ends and a shaft; found in the limbs Flat bones relatively thin; protective Short bones – small and cube-like Irregular bones none of the above; have a more complex shape Sesamoid bones found embedded within tendons Sutural (Wormian) bones – tiny and jagged; = “islands” of bone found within cranial sutures
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2 Fig. 6-2a, p. 188 The structure of long bones Diaphysis = the shaft; it consists mostly of compact bone Marrow (medullary) cavity – contains red (blood-forming) or yellow (fat) marrow… In children and adults, respectively Epiphyses = the ends; they consist mostly of spongy bone Metaphysis = the union between the shaft and ends – Growing bone contains epiphyseal plates (which are made of hyaline cartilage) • When these plates completely ossify, they become epiphyseal lines Articular cartilage = smooth hyaline cartilage that covers the articulating surfaces of bones – Functions: reduces friction, absorbs shock Fig. 6-2b, p. 188 The structure of flat bones (and the other bone shapes besides long bones) • They have a thin covering (= cortex ) of compact bone, and a spongy bone filling (= diploë )
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3 Bone histology – the matrix of bone • Mineral salts (which make up ~ 67% of bone) – provide hardness and resistance to compression – like concrete – The specific mineral salts in bone form hydroxyapatite crystals • These are mainly made up of calcium phosphate [Ca 3 (PO 4 ) 2 ] and calcium hydroxide [Ca(OH) 2 ] • They also incorporate calcium carbonate [CaCO 3 ] and other ions (e.g. Na + , Mg 2+ , Fl - ) • Collagen fibers (which make up ~ 31% of bone) – provide tensile strength and resistance to twisting and bending – like the steel rebar that reinforces concrete Fig. 6-15, p. 203 Fig. 6-3, p. 190 Bone histology – the cells • Make up ~ 2% of bone • There are 4 main types : – Osteoprogenitor cells – Osteoblasts – Osteocytes – Osteoclasts
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4 Osteoprogenitor cells • Are stem cells (“-progenitor” = “ancestor” or “gives rise to”) • Are derived from mesenchyme (like all CTs) • Osteoprogenitor mitosis + differentiation osteoblasts • Are found in : – The inner cellular (osteogenic) layer of the periosteum – The lining (endosteum) of the marrow cavities – The lining of central (Haversian) canals and perforating (Volkmann’s) canals • Function : develop into new
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This note was uploaded on 12/29/2011 for the course BIOLOGY 24011 taught by Professor Pan during the Fall '11 term at HCCS.

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BIOL&251Ch6NotesSpr11 - Ch. 6 Osseous (Bony) Tissue and...

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