Support Protection Movement Mineral storage Blood cell formation (hemopoiesis) Triglyceride storage

Distal epiphysis Proximal epiphysis diaphysis yellow marrow epiphyseal line periosteum compact bone spongy bone Endosteum hyaline cartilage Sharpey’s fibers

spongy bone central canal compact bone Haversian system osteocyte periosteum

osteocytes in lacunae central canal canaliculi in matrix

275 bones 12 weeks (6-9 inches long)

Fig

cartilage calcified cartilage bone epiphyseal plate epiphyseal line Endochondral Ossification 2 o ossification center Fetus: 1 st 2 months AdultChildhood Just before birth

Fig

GH from anterior pituitary, which is regulated by T3 and T4 of the thyroid During puberty- sex hormones: estrogen and testosterone Hyposecretion of GH- dwarfism Hypersecretion of GH- gigantism

Parathyroid hormone- stimulates osteoclastsParathyroid hormone- stimulates osteoclasts Calcitonin- inhibits osteoclastsCalcitonin- inhibits osteoclasts Parathyroid hormone- stimulates osteoclastsParathyroid hormone- stimulates osteoclasts Calcitonin- inhibits osteoclastsCalcitonin- inhibits osteoclasts Maintains homeostasis

Osteoblast Osteocyte Osteoclast Eats bone Builds new bone Mature bone cell

hematoma callus bony callus bone 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

ObliqueComminutedSpiralCompound

1.Electrical stimulation of the fracture site: Increases speed and completeness of healing The e- stimulation inhibits PTH and slow osteoclasts down from reabsorbing bone 2. 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 treatments 4. 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

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 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?