1. Ch 6.3-Bone Structure

2. Macroscopic Structure -Diaphysis (growing between) -Bone’s shaft; main portion of bone -Epiphyses (growing over) -Distal/Proximal ends of bone -Metaphyses -Region where diaphysis joins epiphyses -Only in mature bones -Articuluar cartilage -Layer of cartilage covering epiphysis Articular cartilage Proximal epiphysis Metaphysis Diaphysis Metaphysis Distal epiphysis Humerus

3. Macroscopic Structure -Periosteum (peri- = around) -Dense connective tissue surrounding bone -Stimulates bone growth → thickness -Protects, repairs, nourishes, attaches -Medullary (marrow) cavity -Hollow space containing yellow marrow -Endosteum (endo- = within) -Thin layer lining medullary cavity -Contains bone-forming cells Articular cartilage Endosteum Medullary cavity Periosteum Articular cartilage Proximal epiphysis Metaphysis Diaphysis Metaphysis Distal epiphysis Humerus

5. Microscopic Structure -Extracellular matrix -25% water -25% collagen fibers -50% crystallized mineral salts -Calcification: mineral salts deposited on to collagen framework

6. Different Types of Cells Osteogenic Cell Osteoblast Osteocyte Osteoclast -Unspecialized stem cells -Found in periosteum and endosteum -Develops into osteoblast -Bone-building cells -Forms EC matrix -Mature bone cells -Maintain daily metabolism and bone tissue -Fusion of many monocytes -Found in endosteum -Release lysosomal enzymes and acids -Breakdown EC matrix

7. Osteocyte Concentric lamellae Osteon -Miniature canal system -Provides many routes for nutrients and oxygen

8. Compact vs Spongy Bone Tissue Compact Bone -Strongest type of bone -Directly beneath periosteum -Contains osteons -Makes up most of diaphysis in long bones -Protection, support, and resists stress Spongy Bone -Does not contain osteons -Consists of trabeculae (irregular latticework) -Osteocytes -Concentric lamellae -Makes up most of short, flat, and irregular bones -Support and protect red bone marrow

9. Compact bone Spongy bone Compact bone Spongy bone Trabeculae

11. Bone Scanning