The Skeletal System

1. The Skeletal System Chapter 6, 7,& 8 Martini, 1st Ed. Anatomy and Physiology Liberty Senior High School

2. Question of the Day! Do bones remain the same? How do bones �know� when to stop growing? What happens when they don�t?

3. The Skeletal System! Our First System Cells (Osteocytes) Tissues (Osseous Tissue) Organs (Bones) Systems (Skeletal)

4. All C.T. have Three Parts 1. Specialized Cells 2. Extracellular Protein Fibers 3. The Fibers above and a ground substance (usually a liquid)- make up the Matrix that surrounds cells. (most of the volume of C.T.)

5. The Fibers Collagen Fibers- long, straight, unbranched, fibers of twisted protein; rope-like, very flexible, yet strong. (Tendons and Ligaments)

6. The Matrix G.S. = almost no liquid; collagen fibers + calcium salts (CaPO4 and some CaCO3) Strong and flexible properties. Lacunae in matrix contain osteocytes.

7. Bone (Osseous Tissue) Lacunae organized around a central canal (Haversian canal) which contains blood vessels. Diffusion cannot occur through calcium salts. Cytoplasm of osteocytes extend to central canal by canaliculi.

8. A Basic Pattern in Bone Tissue Lacunae with osteocytes arranged around and connected to a central canal by radiating canaliculi- Osteon Many osteons in one bone.

9. Bone-Low Mag.

10. Bone-High Mag.

11. Osteons

12. Haversian or Central Canal

13. Two Types of Osseous Tissue 1. Compact bone- dense bone, solid, more on surface of bone, shaft of bone. Function: osteons are all alligned;strengthen bone, the tissue of bone is parallel to stresses.

14. Two Types of Osseous Tissue 2. Spongy Bone- open network of trabeculae which are struts and plates in the interior of bone (matrix) , light in weight; Function: has no osteons; withstand stress from a variety of directions, reduce the weight of the overall bone.

17. Bone (Osseous Tissue) Bone surfaces covered by periosteum- fibrous layer of C.T.; attachment for tendons and ligaments. Site of appositional growth of bone. Bone is constantly remodeled- grow thicker with stresses.

21. Bone Development & Growth

22. Osteogenesis Ossification- formation of bone is a dynamic process. Osteoblasts- produce new bone matrix. Osteoclasts- produce acids and enzymes to release the stored minerals in the matrix. Osteocytes- mature bone cells that do not divide.

23. Osteoblasts

25. Osteoclasts

27. Bone Cell Interaction

28. 2 types of Ossification

29. Intramembranous ossification Occurs in the deeper layers of the dermis- Dermal bones Ex: top of skull, mandible, clavicle, abnormal stressed areas like tendons, joints, skeletal muscles (heterotopic bones- different place)

30. Intramembranous ossification

31. Intramembranous ossification

32. Intramembranous ossification

39. Endochondral Ossification 1. Hyaline chondrocytes die & disintegrate leaving cavities within cartilage. 2. Blood vessels grow at edges & perichondrial cells become osteoblasts (turns to bone on the edges).

40. Endochondral Ossification

41. Endochondral Ossification 4. Osteoclasts- create a marrow cavity by dissolving struts

42. Endochondral Ossification Increasing the Length Osteoblasts of the diaphysis and chrondrocytes of epiphysis continue to grow; elongate bone. Epiphyseal Plate is this interface between the two.

43. Endochondral Ossification

44. Endochondral Ossification 6. Epiphysis is filled with spongy bone -Articular cartilage remains at exposed joint cavity -At the metaphysis, epiphyseal plate separates the epiphysis from the diaphysis

45. Endochondral Ossification

50. Bone Formation In An Embryo

51. Growth Plate

52. Endochondral Ossification

53. Fetal Long Bone

54. Developing Long Bone

56. Increasing the Diameter

59. Achondroplasia

60. When bones don�t stop growing!