Bone

Bone

1. Functions

   • support
   • leverage
   • protection
   • storage of minerals + lipids
   • hematopoiesis (production of blood cells)

2. Structure of Bone

   • Matrix
     • Organic (OSTEOID)
       • 33% OF BONE - TENSILE STRENGTH - FLEXIBILITY
       • collagen type I (eosinophilic)
       • glycoproteins, proteoglycans
     • Inorganic
       • 66% of BONE -COMPRESSIONAL STRENGTH -MINERAL STORAGE
       • hydroxyapatite
         • calcium
         • phosphate
   • Cells
     • Osteoprogenitor
       • - stem cell; embryonic mesenchyme  - divides into osteoblasts
     • Osteoblasts
       • produce, secrete & ca;cofy osteoid; ranges from cuboidal to squamous
     • Osteocytes
       • mature bone cell that maintains the matrix; in lacunae, surrounded by a small amount of unmineralized matrix; cell processes extend through canaliculi to communicate via gap jxns; fxn is to maintain surrounding bone tissue, sense mechanical stresses and organize bone remodelling accordingly
     • Osteoclasts
       • multinuclear cells from the monocyte/macrophage cell lineage; found at bone surface in Howship (resorption) lacunae; secrete acids, enzymes for osteolysis, releases Ca 2+, PO4; displays "ruffled border" with activity
   • Types of Bone
     • Spongy (tracebular, cancellous)
     • Compact (lamellar)
   • Bone Coverings
     • Periosteum
     • Endosteum

3. Ossification

   • Intramembraneous
   • Endochondral

4. Bone Remodelling

5. Bone Growth, Maintenance & Repair