Osseous Tissue (Histology)

Review: Bone is a type of connective tissue 2 Parts: 1. Cells (living) 2. Matrix (nonliving substance released by cells) A. Fiber B. Ground Substance

1. Cells 2. Matrix Osteocytes— mature bone cells Osteoblasts— bone-forming cells (germ cells or “bud” cells) Osteoclasts —bone-destroying cells (“breakers”) A. primarily collagen fibers flexibility tensile strength (the strength to endure stretching forces) B. calcium salts (hardness) contain calcium and phosphorus great compressional strength (the strength to endure squeezing forces) 2. Matrix

Classification of Bone by Tissue Type Two basic types of Tissue 1. Compact bone Homogeneous Looks “smooth” 2. Spongy bone Small needle-like pieces of bone Many open spaces (like sponge) Keep bones light Figure 5.2b

Microscopic Anatomy of Bone Figure 5.3a http://www.youtube.com/watch?v=4qTiw8lyYbs&NR=1

Microscopic Anatomy of Bone Osteon (Haversian system) A unit of bone containing central canal and matrix rings Central (Haversian) canal Opening in the center of an osteon Carries blood vessels and nerves Perforating (Volkman’s) canal Canal perpendicular to the central canal

Microscopic Anatomy of Bone Lacunae Cavities containing bone cells (osteocytes) Arranged in concentric rings Lamellae Rings around the central canal Sites of lacunae

Microscopic Anatomy of Bone Canaliculi Tiny canals Radiate from the central canal to lacunae Form a transport system connecting all bone cells to a nutrient supply

Microscopic Anatomy of Bone Figure 5.3b–c