1. Missing Notes, Unit 3
Hi folks, these are just a few more slides to round out the discussion we had today. I am purposely leaving out the osteogenesis information – you won’t have to know that for this exam. Remember that this information is also in chapter 6. Good luck!

2. Bone Cell Types Four types of cells are found in bone:
Osteoprogenitor – bone stem cells found in the endosteum and periosteum, which divide to become another stem cell or an osteoblast.
Osteoblast – forms bone matrix (builds bone), differentiates into osteocytes

3. Bone Cell Types
Osteocytes – maintain the bone matrix from within lacunae
Osteoclasts – large multinuclear cells that dissolve bone. Osteoclasts and osteoblasts have opposite effects on bone density and blood Ca++ level

4. Bone Cell Types

5. Compact Bone Microstructure
The cylindrical structure called the osteon or the Haversian system is the basic structural unit of mature compact bone. Osteons run parallel to compression forces of the bone.
Haversian canals are the central openings in osteons and contain blood vessels and nerves.
Concentric lamellae are the layers surrounding the Haversian canal.

7. Osteon or Haversian System
Lacunae are the spaces within the bone containing osteocytes.
Canaliculi are the small tubules that connect lacunae, and allow cytoplasmic communication.