anatomy class notes 2

anatomy class notes 2 - EC pick 1 qst write essay due nooon...

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EC – pick 1 qst – write essay – due nooon on exam day Citations needed, thesis, arguments, etc… 5-10 pages 5/1/08 The Skeletal System The Skeleton consists of: o Bones o Cartilage o Joints o Ligaments Skeletal System consists of live and dynamic tissue – functions: o Protection – covering soft organs o Support – internal framework o Movement – jints and bones are leverage points and fulcra for muscles o Hematopoiesis – production of blood cells – red marrow o Mineral reservoir – storage of calcium, phosphate, magnesium, carbonate, and others Bones are constantly remodeling themselves o Osteoblasts – create bones Flat when inactive (lining cells) Rounded when activated Deposit osteoid, which subsequently becomes mineralized mostly composed of collagen fibers As an osteoblast becomes encapsulated in osteoid, it matured and becomes an osteocyte Arise from osteoprogenitor cells Collagen fibers o Osteoclasts – cells that destroy bone Form by activation and fusion of several preosteoclasts (multinucleate) Surface touching bone is ruffled in order to increase surface area Secrete Lysosomal enzymes – destroy anything organic Hydrochloric acid – destroy other stuff o Remodeling units – osteoblasts and clasts together Organic matrix – osteocyte, osteocytes, osteoblasts, and everything together. Layed down by osteoblasts – primarily made of collagen fibers Inorganic matrix – there are clalcium phosphate, calcium carbonate crystals called hydroxyapatite crystals – responsible for making bone hard. Without crystals – bone is really flexible because its collagen fibers Compact bone – dense – handle most of bone stresses Spongy bone – looks like a sponge, (cancellous bone) – structural support and strength, but light in weight as well o Histology of Compact Bone Resists torsion, beding, etc… made of osseous tissue
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Organized into osteons, which are pillars which help with weight bearing. They consists of rings of tissue called a Lamella (which is made of inorganic and organic matrix). They all surround a central cavity called the central canal or Haversian canal with at least one artery, vein, and nerves. The lamella are made of collagen fibers which run in one direction and then the next lamella is in another arrangement so it is a cross hatch arrangement of collagen fibers – this helps with the resisting of twisting in any direction along with the weight bearing. Interface between lamella there are holes (lacunae with osteocytes in them) 3 lamellae Haversian lamellae – blood vessels – surrounds each osteon Interstitial lamellae – fills in the gaps between osteons Circumferential lamellae – form cortex around lamellae Periostium – covering of the bone – all blood vessels are connected to major blood vessel in the periostium o Histology of Spongy Bone (cancellous) Has trabecula (struts in them) – made of osseous tissue. Inorganic, organic
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anatomy class notes 2 - EC pick 1 qst write essay due nooon...

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