• Support• Protection• Movement• Mineral storage• Blood cell formation

(hemopoiesis)• Triglyceride storage

Distalepiphysis

Proximal epiphysis

diaphysis

yellow marrow

epiphyseal line

periosteum

compact bone

spongy bone

Endosteum

hyaline cartilage

Sharpey’s fibers

spongybone

central canal

compact bone

Haversian system

osteocyte

periosteum

osteocytes osteocytes in lacunaein lacunae

central central canalcanal

canaliculi canaliculi in matrixin matrix

275 bones12 weeks (6-9 inches long)

Fig. 06.13

cartilagecalcified cartilage

bone

epiphyseal plate

epiphyseal line

Endochondral Ossification

2o ossification center

Fetus: 1st 2 months

AdultChildhood

Just before birth

Fig. 06.08

• GH from anterior pituitary, which is regulated by T3 and T4 of the thyroid

• During puberty- sex hormones: estrogen and testosterone

Hyposecretion of GH- dwarfismHypersecretion of GH- gigantism

• Parathyroid hormoneParathyroid hormone- stimulates - stimulates osteoclastsosteoclasts

• CalcitoninCalcitonin- inhibits osteoclasts- inhibits osteoclasts

Maintains homeostasis

Osteoblast

Osteocyte

OsteoclastEats bone

Builds new bone

Mature bone cell

hematoma callus bony callusbone remodeling

Usually treated by realignment• Simple- closed fracture (8-12 wks to heal)

bone breaks cleanly; no penetration • Compound- bone penetrates through skin • Comminuted- bone fragments into many

pieces; aged or brittle bones • Compression- bone is crushed • Depressed- broken bone portion is

depressed inward• Impacted- broken bone ends are forced into

each other• Spiral- excessive twisting of bone• Greenstick- bone breaks incompletely

Oblique Comminuted Spiral Compound

1. Electrical stimulation of the fracture site:• Increases speed and completeness of healing• The e- stimulation inhibits PTH and slow osteoclasts

down from reabsorbing bone2. Ultrasound treatment:• Daily treatments reduce healing time of broken bones

by 25-35%3. Free vascular fibular graft technique:• Transplant fibula in arm• Gives good blood supply not available in other

treatments4. Bone substitutes:• Crushed bone from cadaver- but risk of HIV and

hepatitis• Sea bone- coral• Artificial bone- ceramic

Osteoporosis- bone reabsorption outpaces bone deposit; bones become lighter and fracture easier

Factors: • age, gender (more in women)• estrogen and testosterone decrease• insufficient exercise (or too much)• diet poor in Ca++ and protein• abnormal vitamin D receptors• smoking

29 40 84 92

• Rickets- vitamin D deficiency

• Osteomalacia- soft bones, inadequate mineralization in bones, lack of vitamin D

• Pagets Disease- spotty weakening in the bones, excessive and abnormal bone remodeling

• Rheumatoid arthritis- autoimmune reaction

INQUIRY

http://www.youtube.com/watch?v=DSHoonPWwXQ

1. What does the secondary site of ossification produce?

2. What is an epiphyseal line?3. Provide an example of a flat bone?4. How does PTH effect bone development?5. How many bones in the adult skeleton?6. What does an osteoblast do and where are they

primarily found?