1. Chapter 6
The Skeletal System

2. Skeletal System Functions
Support
Storage
Protection
Leverage/Movement
Red and white blood cell production

3. Bone Shapes Long Short Flat Irregular Upper and lower limbs
Carpals and tarsals
Flat
Ribs, sternum, skull, scapulae
Irregular
Vertebrae, facial

4. Long Bone Structure Diaphysis Epiphysis Epiphyseal plate
Shaft
Compact bone
Epiphysis
End of the bone
Cancellous bone
Epiphyseal plate
Growth plate
Epiphyseal line
Bone stops growing in length

5. Long Bone Structure Medullary cavity Periosteum Endosteum Red marrow
Yellow marrow
Periosteum
Outer bone surface
Fibrous outer layer
Endosteum
Lines bone cavities
Lines marrow cavities

6. Long Bone Structure

7. Flat, Short, Irregular Bones
Flat Bones
No diaphyses, epiphyses
Sandwich of spongy cancellous between dense compact bone
Short and Irregular Bone
Compact bone that surrounds spongy cancellous bone center
No diaphyses and not elongated

8. Bone Histology Bone cells: Cancellous bone Compact bone
Osteocytes (mature bone cells)
Osteoblasts (build bone)
Osteoclasts (break down bone)
Cancellous bone
Spongy bone with trabeculae
Compact bone
Dense bone

9. Bone Matrix

10. Bone Cells Osteoblasts Osteocytes Osteoclasts
Formation of bone through ossification
Osteocytes
Mature bone cells
Lacunae: Spaces
Canaliculi: Canals
Osteoclasts
Responsible for bone resorption

11. Cancellous Bone Spongy bone consisting of trabeculae
Oriented along lines of stress

12. Compact Bone
Central or haversian canals: Parallel to long axis with vessels
Lamellae: Concentric, circumferential units of bone
Osteon or haversian system: Basic functional unit of bone
Perforating canals: Perpendicular and provide links to vessels

13. Bone Development Intramembranous ossification
Takes place in connective tissue membrane
Skull bone formation
Endochondral ossification
Takes place in cartilage
Long bone formation
Both methods of ossification
Produce woven bone that is then remodeled
After remodeling, formation cannot be distinguished as one or other

14. Intramembranous Ossification

15. Endochondral Ossification

16. Endochondral Ossification

17. Endochondral Ossification

18. Growth in Bone Width

19. Factors Affecting Bone Growth
Nutrition
Vitamin D
Necessary for absorption of calcium from intestines
Insufficient causes rickets and osteomalacia
Vitamin C
Necessary for collagen synthesis by osteoblasts
Deficiency results in scurvy
Hormones
Growth hormone from anterior pituitary
Thyroid hormone required for growth of all tissues
Sex hormones as estrogen and testosterone

20. Bone Remodeling Coverts woven bone into lamellar bone
Bone constantly removed by osteoclasts and new bone formed by osteoblasts

21. Bone Repair

22. Bone Repair

23. Calcium Homeostasis
Bone is the major storage site for calcium in the body
Calcium moves into bone as osteoblasts build new bone
Calcium moves out of bone as osteoclasts break down bone
When osteoclast and osteoblast activity is balanced, the movement of calcium in and out is equal

24. Calcium Homeostasis

25. Effects of Aging on Skeletal System
Bone Matrix decreases
Bone Mass decreases
Increased bone fractures
Bone loss causes deformity, loss of height, pain, stiffness
Stooped posture
Loss of teeth

26. Bone Fractures