1. DEVELOPMENT and GROWTH
BONE TISSUE
DEVELOPMENT and GROWTH

2. FUNCTIONS Support/Movement Protection Mineral reservoir
Site of blood cell production
Storage of fat

3. Skeletal Cartilage Consists primarily of water
Contains no nerves or blood vessels
Surrounded by perichondrium
Dense irregular connective tissue
Maintains shape

4. Skeletal Cartilage Basic components 3 Types Chondrocytes in lacunae
Extracellular matrix with jellylike ground substance
3 Types
Hyaline
Elastic
Fibrocartilage

5. Hyaline Cartilage Most abundant Fiber not detectable Locations
Articular cartilage
Costal cartilage
Respiratory cartilage
Nasal cartilage

6. Elastic Cartilage Contains more elastic fibers; more flexible
Found in ear and epiglottis

7. Fibrocartilage Highly compressible Great strength Locations Knee
Vertebral disks

8. Cartilage Growth Two methods Growth stops during adolescence
Appositional – adds to outside
Interstitial – growth from inside
Growth stops during adolescence

9. Bone Histology - Cell Types
Osteocytes – mature bone cells
Osteoblasts – bone forming cells
Osteoclasts – bone destroyers

10. Process by which tissue becomes bone Also called osteogenesis
BONE OSSIFICATION
Process by which tissue becomes bone
Also called osteogenesis

11. Bone Formation
Bone formation begins approx. 8 weeks into fetal development from a skeleton that is mostly fibrous membranes and cartilage
Intramembranous ossification – bone forms from the fibrous membranes
Endochondral ossification – bone forms from hyaline cartilage

12. Intramembranous Ossification
Osteoprogenitor (mesenchymal) cells in fibrous C.T. develop into osteoblasts
Osteoblasts secrete collagen matrix
Calcification occurs in ossification centers; forming a network of bone rather than layers
Bony plates form which are later converted into compact bone
Flat bones only; skull & clavicles
Fontanelles are areas not ossified at birth

13. ENDOCHONDRAL OSSIFICATION
Forms most bones
Hyaline cartilage model in shape of the bone initially; a pH change causes cartilage to calcify and the cells to die
Primary ossification center forms as blood vessels from periosteum and osteoblasts invade calcified cartilage
Matrix formed (osteoid= unmineralized bone matrix)
Ossification occurs = calcium salts deposited
Primary centers form before birth; Secondary centers form 8th month dev.

14. Epiphyseal Plate
Cartilage region between primary and secondary ossification centers
Responsible for postnatal bone growth
Zone of resting cartilage
Growth Zone – mitosis occurs
Transformation Zone – cartilage matrix deteriorates
Osteogenic Zone - bone salts deposited

16. Calcium regulation
Calcium is most abundant mineral in the body; 99% located in the bone
Regulated by two hormones: PTH (parathyroid hormone) and calcitonin
PTH - raises blood calcium levels
Calcitonin - lowers blood calcium levels

17. Hormones and Vitamin Effect on Bone Growth
Testosterone
Estrogen
Growth Hormone
Throxine -
Vitamin D – calcium absorption

18. Bone Types Compact Bone Cancellous Contains osteons Trabeculae
also called dense bone
hard, strong and solid bone that forms the outer layer of all bone
provides support, protection and resists stress
Contains osteons
Cancellous
also called spongy bone
found more toward the inner portion of bone
open lattice-work of struts and plates that serves to store bone marrow
Trabeculae

19. Osteons = Haversian System
Haversian canal
Volkmann’s canals
Lamellae
Lacunae
Canaliculi

20. Bone Types Long – arms and legs Short – wrist and ankle
Sesamoid – forms within a tendon (patella)
Flat – sternum, scapula, ribs, skull
Irregular – vertebrae & coxal bones

21. Structure of a Long Bone
Diaphysis
Epiphysis
Articular cartilage
Periosteum – connective tissue covering bone
Medullary cavity
Endosteum – connective tissue; lines inside

23. Bone Fractures Open ( Compound) – penetrates skin Closed (Simple)
Partial/Complete - Greenstick
Comminuted – broken into 3 or more pieces

24. Bone Repair Formation of clot ( hematoma)
Callus ( soft followed by hard)
Mineralization of callus by calcium & phosphorus
Remodeling