Chapter 6- Bone & Skeletal

• high tensile strength
• meniscous= pad-like cartilage in knee
• articular=in joints
• location: intervertebral disks

1. appositional growth (outside): cartilage-forming cells secrete new matrix on external face
2. interstitial growth (within): lucanae chondrocytes proliferate/secrete matrix

1. protection
2. support
3. movement
4. mineral stroage
5. blood cell formation-HEMATOPOESIS w/in marrow cavities

• Calcium and phosphate release and store
• when calcium is low we have to break it down

1. axial: head, vertebral column, ribs
2. appendicular: limbs

1. long bones: ex-femur
2. short bones: ex-carpals
3. irregular bones: ex-vertebrae
4. flat bones: ex-sternum

1. compact bone
2. spongy bone

• smooth, very hard, outside, ridgid

• diplode
• help redistribute stress on bone
• marrow inside
• ALWAYS with compact bone

1. Epiphysis-region at top of long bone
2. Diaphysis- shaft of bone

• SPONGY AND COMPACT
• expanded ends of long bone
• joint surface is covered with articular (hyaline) cartilage
• epiphyseal line is where growth plate is located

• tubular shaft that forms the axis of long bone
• hard, continuous bone....COMPACT only
• hollow center for YELLOW marrow

PERIOSTEUM

1. outter fibrous layer
2. inner osteogenic layer

***made up of osteoblast and osteoclast

1. osteogenic- stem cell
2. osteoblast- responsible for BONE GROWTH
3. osteocyte- maintains bone matrix, REPAIR
4. osteoclast-breaks down bone

• make up compact bone
• "holes"-basic unit of compact bone
• made of conventric layers of mineralized collagen
• consist of multiple lamellae that each go different directions
• inside Haversian Canal
• later become mineralized= stronger

• thin plates of periosteum-covered compact bone on outside with endosteum-covered spongy bone on inside
• do not have a diaphysis and epiphysis
• contain bone marrow BETWEEEN trebuculem

• found in hollow spaces of bone
• RED MARROW
• in INFANTS:
• medullary cavity of diaphysis
• all areas of spongy bone
• in ADULTS:
• trabeculae of flat bones and head of femur and humerus ONLY

• INORGANIC
• hydroxapatites, or mineral salts
• 65% of bone by mass
• mainly calcium phosphate
• responsible for bone hardness & resistance to compression

• ossification=osteogenesis
• embryo-formation of bony skeleton (template-cartilage)
• until adulthood- bone growth
• adult- bone remodeling

• intramembranous ossification- make bone between membrane
• ex: flat bone
• osteoblast lays down osteiod and later mineralizes or become osteocytes

• Cartilage
• Endochondral ossification- replace cartilage with bone
• use caritlage as template

From bottom up

• proliferation zone-mitosis
• hypertrophic zone-cells get bigger
• calcification zone- cartilage cells die
• growth along epiphyseal plate

• growth hormone- stimulates growth
• disorder=dwarfism
• thyroid hormones (T3, T4)- modulates activity
• balance of oseocytes and osteoblasts determines if bones get stronger or weaker

• new bone formation
• osteoblast cells
• occurs after injury or for additional strength
• Vtiamin C- collagen synthesis
• Vitamin D- calcium absorption
• Vitamin A- balance deposit & resorption
• minerals: Ca, Phosphorus, Magnesium

• osteoclast use enzymes to break down inorganic materials (MATRIX)
• osteoclast come from macrophages
• raise blood balcium levels/ remove necrotic debree
• lysosomal enzymes-digest organic matrix
• acids-convert calcium salts to soluble form

• inadequate bone mineralization (normal production of ostoid)
• pain when weighted
• rickets- children
• bow legs
• deformities to pelvis, skull, rib cage, and femur
• nutrition--Vitamin D
• common in poor developing countries

• bone resorption greater than bone deposit
• matrix compostion is normal
• loss in height

• excessive bone formation and breakdown
• abnormal ratio of spongy bone to compact bone
• poor mineralization of new bone
• may be viral in origin
• over production of spongy bone- not completely covered by compact

1. hematoma forms
2. fibrocartilaginous callus forms
3. boney callus
4. bone remodeling