2. Types of Bone Cells Slide 5.15 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Osteocytes  Mature bone cells  Osteoblasts  Bone-forming cells  Osteoclasts  Bone-destroying cells  Break down bone matrix for remodeling and release of calcium

3. Bone Development Slide 5.12 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  In embryos, the skeleton is primarily hyaline cartilage  Uses hyaline cartilage “bones” for bone construction  During development, much of this cartilage is replaced by bone  Begins in second month of development  Bone Development Bone Development

4. Bone Growth Slide 5.13a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Epiphyseal plates allow for growth of long bone during childhood  New cartilage is continuously formed  Older cartilage becomes ossified  Cartilage is broken down  Bone replaces cartilage Bone Growth Animation

5. Hormonal Regulation of Bone Growth During Youth During infancy and childhood, epiphyseal plate activity is stimulated by growth hormone During puberty, testosterone and estrogens: Initially promote adolescent growth spurts Cause masculinization and feminization of specific parts of the skeleton Later induce epiphyseal plate closure, ending longitudinal bone growth

6. Bone Remodeling Bones are remodeled continually in response to changes in two factors: Calcium Levels in the blood The pull of gravity and muscles on the skeleton

7. Bone remodeling When blood calcium levels drop below homeostatic levels, the parathyroid glands release Parathyroid hormone PTH activates osteoclasts to break down bone matrix and release calcium ions into the blood Bone remodeling is essential if bones are to retain normal proportions and strength during long-bone growth Accounts for the fact that bones become thicker and form large projections to increase strength in areas where bulky muscles are attached

9. Bone Fractures  A break in a bone  Types of bone fractures  Closed (simple) fracture – break that does not penetrate the skin  Open (compound) fracture – broken bone penetrates through the skin  Displaced – the bone snaps into two or more parts and moves sot that the two ends are NOT lined up straight  Non-displaced – the bone cracks either part of all of the way through, but does move and maintains its proper alignment

10. Today’s Assignment You are a radiologist for HASPI Hospital and it is a busy day! Six patients are waiting for you to view their X-Rays. The X- Rays are spread throughout the room, and a normal X-Ray has been includedwith each X-Ray for comparison. A mini version of each X-Ray has been included on this lab sheet for reference. Analyze each patient X-Ray and answer the question in the boxes provided. Remember the following steps when analyzing: Where am I? Compare it to the normal X-Ray Is Everything Aligned? Check the outer cortex for any obvious misalignment

11. In addition to the terms we wrote down above, you must first know the types of fractures possible. In your Notebook glue in both the diagram of breaks and the types of fractures chart. Fill in the chart before getting started! Types of Fractures…