Bone

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Bone
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• COMPONENTS OF BONE
• OSTEOCYTES LIVING BONE CELLSResponsible for the
  growth, repair, and remodeling of the
  intercellular matrix.
• B. Intercellular Matrix "Non-Living" bone
  substance which is composed of three elements
• 1. Gelatin the GROUND SUBSTANCE
• 2. COLLAGEN FIBERS
• 3. CRYSTALLINE SALTS Ca 2 Carbonates and Ca
  2 Phosphates

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Sites of osteoperotic fractures
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BALANCE OF SYNTHESIS (building of new matrix) and
RESORPTION (the destruction of the matrix) is
controlled by four factors A. DIET B.
HORMONES C. EXERCISE D. AGE
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BONE FORMATION (Osteoblasts) Stimulated by ()
Calcitonin, Androgens, Growth Hormone, Insulin
Inhibited by (-) Parathyroid Hormone (PTH),
Cortisol BONE RESORPTION (Osteoclasts) Stimulate
d by () PTH, Thyroid Hormones (T3), Cortisol,
Vit. D Inhibited by (-) Calcitonin, Estrogens
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IN ADULT BONE inorganic crystals make up 75 of
intracellularmatrix- makes bones rigid The
remaining 25 of matrix is composed of organic
materials (ground substance (15) and collagen
fibers (35) ). BONE DENSITY DETERMINED
BY Percentage of crystalline salts the more
salts per unit of volume, the higher the density.
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• BONE TISSUE
• Basic Functions
• Support - of soft tissues and attachment sites
  for muscles, creating a framework for the body.
• 2. Protection - of internal organs by bones which
  overlie and/or surround them.
• 3. Movement - facilitated since bones provide
  leverage for muscle contraction.
• 4. Mineral homeostasis - particularly Ca and P,
  occurs as minerals are stored in and mobilized
  from bones.
• 5. Blood cell production - erythropoesis in red
  bone marrow.
• 6. Storage of energy - lipids found in yellow
  bone marrow