The Skeletal System Part Two

C. Microscopic Features of Bone a)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. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

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

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