The Skeletal System Part Two

C. Microscopic Features of Bonea) Osteocytes - bone cells that sit in

small pocket called lacunae.

b) Lacunae – are found between narrow sheets of calcified matrix that are known as lamellae.

c) Small channels called canaliculi, radiate through the matrix, interconnecting lacunae and linking them to nearby blood vessels.

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The Structure of Bone

Figure 6-3(a)

The Structure of Bone

Structure of a Typical Bone

Figure 6-3(b)

E. Cells in Bone– Osteocytes

• Mature bone cells between lamellae

– Osteoclasts• Source of acid, enzymes for osteolysis• Calcium homeostasis

– Osteoblasts• Responsible for osteogenesis (new bone)• Source of collagen, calcium salts

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III. Bone Formation and Growth

• Intramembranous Ossification (cartilage is not present)– Ossification—Process of converting other tissues to

bone– Forms flat bones of skull, mandible, clavicle

• Endochondral ossification– Forms long bones, spongy bone to compact bone

Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Bone Formation and Growth

Bone Formation in 16-Week-Old Fetus

Figure 6-4