1. The Skeletal System- Osseous Tissue & Skeletal Structure

2. The skeletal system includes:
Bones
Cartilage
Joints
Ligaments
Other connective tissues

3. Functions of the Skeletal System
Support against gravity
Protection of soft internal organs
Movement (Leverage)
Storage
Minerals (calcium, phosphorous) – within the matrix of bone tissue
Energy reserve (adipose) – within the yellow marrow of long bones
Blood cell production – within red marrow of spongy bone tissue

4. Bone tissue Anatomy of a bone Structure of bone tissue
Formation and growth of bone
Fracture and repair
Effects of physiological processes on bone

5. Anatomical Classification of Bones
Bones are classified by their basic shape
Flat bones
Sutural bones
Irregular bones
Long bones
Short bones
Sesamoid bones

6. The parts of a long bone Diaphysis-shaft Epiphyses- ends
Come together at metaphyses
Articular cartilage protects epiphyses
Periosteum covers bone
Medullary cavity contains marrow; is lined by endosteum

8. Bone cells

9. Organization of bone tissue
compact
spongy

10. Compact vs. spongy bone Compact bone Spongy bone External layer
Arranged in osteons
Lamellae are found around periphery and between osteons
Central canals connected to each other by perforating canals
Spongy bone
No osteons
Arranged in trabeculae
Major type of tisse in short, flat, irregular bones
Much lighter than compact bone
Supports red bone marrow

11. Blood and nerve supply to bone
Abundant supply of blood
May have several nutrient arteries
Nerves accompany blood vessels

12. Ossification (osteogenesis)
Bone forms within mesenchyme in layers (intramembranous)
Flat bones of skull and mandible
Osteocytes secrete calcium
Compact and spongy bone form

13. Bone remodeling replaces old tissue
Resorption by osteoclasts, deposition by osteoblasts
Strengthens bone
Repairs damaged bone

14. The Structure of a Typical Bone
All bones have a combination of spongy (cancellous) & compact (dense) bone tissue

15. The Histological Features of Compact Bone
Osteon/Haversian system - basic functional unit of compact bone
Concentric lamellae (layers) of matrix surrounding central (Haversian) canal
Osteocytes located within lacunae
Canaliculi branch out radially from lacunae
Central canals (containing BVs) run vertically down the length of the bone
Perforating (Volkmann’s) canals (containing BVs) run horizontally across the width

16. Bone Cells
In addition to Osteocytes, the mature bone cells found within the matrix of bone tissue, there are three other cells that are associated with bones
Osteoprogenitor cells
Osteoblasts
Osteoclasts

17. Bone Cells Osteoprogenitor cells Derived from mesenchymal cells
Can undergo mitosis
Mature into osteoblasts

18. Bone Cells Osteoblasts
Responsible for osteogenesis – create bone tissue
Mature into osteocytes

19. Bone Cells Osteoclasts Derived from embryological WBCs
Secrete enzymes for osteolysis – resorb/break down bone tissue
Necessary for calcium homeostasis

20. Structure of a Typical Long Bone
diaphysis (compact bone)

21. The Structure of a Long Bone
diaphysis
epiphysis (spongy bone)
epiphysis

22. The Structure of a Long Bone
diaphysis
epiphysis
articular cartilage

23. The Structure of a Long Bone
epiphysis
metaphysis – location of
epiphyseal plate – in children
epiphyseal line – in adults
diaphysis
metaphysis
epiphysis
articular cartilage

24. The Structure of a Long Bone
medullary cavity
filled with yellow marrow in adults
lined with endosteum

25. The Structure of a Long Bone
Outer fibrous layer of dense irregular CT for attachment of tendons& ligaments; provides route for blood vessels & nerves; separates bone tissue from surrounding tissues
Double layered membrane surrounding bone except at articular cartilage
Inner cellular layer contains osteoprogenitor cells, osteoblasts, osteoclasts; therefore functions in bone growth & repair
periosteum

26. Bone Formation and Growth
Ossification - Process of converting other tissues to bone; begins around week 6-8 of embryological development
Two types of ossification processes occur during embryological formation:
Intramembranous
Endochondral

27. An Overview of the Skeleton
There are 206 bones in the adult human body
Skeletal Divisions
Axial skeleton (80 bones)
Skull
Thoracic cage and sternum
Vertebral column
Appendicular skeleton (126 bones)
Upper, lower limbs
Pectoral girdle
Pelvic girdle

28. Types of fracture Stress fracture is not visible;
Overuse or degeneration

29. Process of fracture repair
Bone grows slowly; blood supply may be
affected

30. Life processes and bone formation
Why is exercise good for bones?
How does aging affect bones?
Loss of bone mass due to calcium loss
Decreased production of collagen

31. Treatment of osteoporosis
Prevention
Steroid hormone replacement (stimulates osteoblast activity)
Evista has estrogen-like effects on bone formation
Fosamax blocks bone resorption

32. Summary Bone is a complex tissue It is constantly being remodeled
Bones consist of compact and spongy bone, lots of blood vessels and nerves
Functions of bone:
Support and protection
Movement
Calcium levels
Blood cell formation
Fat storage