1. Skeletal System

2. Functions Support Protection Assist in movement Mineral homeostasis
Blood cell production (hemopoesis)
Triglyceride storage

3. Bone Structure Diaphysis – (long, cylindrical, main portion of bone)
Epiphysis – (distal and proximal ends of bone)
Articular Cartilage – (thin layer of hyline
cartilage covering the
epiphysis where bones
form articulation)
Periosteum – (connective tissue that covers
bone where there is no articular
cartilage)

4. Bone structure continued
Medullary cavity – ( space within diaphysis that
contains fatty yellow bone
marrow)
Endosteum – ( lines medullary cavity and
contains bone forming cells)

6. Composition of bone
25% water
25% Protein fibers
50% mineral salts

7. Histology of bone
Bone cells

8. Osteogenic Cells Only bone cell that can undergo mitosis
Develop into osteoblasts

9. Osteoblasts Bone building cells
Secrete collagen and other organic components

10. Osteocytes Derived from osteoblasts
Form when osteoblasts become entrapped in matrix secretions
“House Keeping” cells

11. Osteoclasts Derived from white blood cells
Maintain normal development, growth, maintenance, and repair of bone

12. Calcification or mineralization
Mineral salts crystallize in the microscopic spaces between collagen fibers
After spaces are filled, mineral crystals crystallize around collagen fibers
Mineral salts include: Calcium phosphate and Calcium carbonate
Collagen and mineral salts make bone rigid yet flexible

13. Compact bone tissue
Haversian system (osteons) make up unit of compact bone
Perforating canals allow blood vessels, lymphatic vessels, and nerves to penetrate bone tissue (run laterally)
Central (Haversian) canals – Run longitudinally and connect to perforating canals
Concentric Lamellae – Hard rings of bone matrix that form around central canals

14. Compact bone tissue continued
Lacunae – Holes that contain osteocytes and are found in lamellae
Canuliculi – Channels filled with extracellular fluid and projections of osteocytes which allow osteocytes to connect with each other and pass blood born nutrients and wastes)

16. Spongy bone Trabeculae – Irregular lattice of thin columns of bone
Spaces between trabeculae are filled with marrow
Makes up most of the tissue of short, flat, and irregular shaped bones; most of the epiphysis of long bones and lines diaphysis
The spongy bone tissue in the hip bones, ribs, breastbone, backbones, and ends of long bones is the only sites of hemopoesis in adults

17. Endochondrial Ossification

18. Development of cartilage model
Mesenchymal cells crowd together in shape of future bone
Mesenchymal cells differentiate into chondrocytes

19. Growth of cartilage model
Model grows in length by chondrocyte cell division
More cartilage is secreted and chondrocytes die

20. Development of primary ossification
Nutrient artery penetrates into model
Osteoblasts move in from periosteum
Osteoblasts deposit bone matrix over calcified cartilage forming spongy bone

21. Development of secondary ossification
The hyaline cartilage of diaphysis is replaced by bone
When nutrient artery penetrates into epiphysis secondary centers form

23. Formation of articular cartilage and epiphyseal plate
Hyaline cartilage becomes articular cartilage
Hyaline cartilage remains between diaphysis and epiphysis as epiphyseal plate which is responsible for lengthwise growth of long bones

25. Axial Skeleton Structure Number of bones Skull 1. Cranium 8 2. Face 14
Hyoid
Auditory ossicles
Vertabral column
Thorax
1. Sternum 1
2. ribs 24

26. Appendicular Skeleton
Structure Number of bones
Pectoral girdles
1. clavicle 2
2. scapula 2
Upper limbs
1. Humerus 2
2. Ulna
3. Radius 2
4. Carpals
5. metacarpals
6. Phalanges

27. Appendicular Skeleton continued
Structure Number of bones
Pelvic Girdle
1. Coxal bone 2
Lower limbs
1. Femur 2
2. Fibula 2
3. Tibia 2
4. patella 2
5. Tarsals 14
6. Metatarsals 10
7. Phalanges 28