BonesBones

Structure, Structure, Remodeling, Remodeling, Homeostatic Homeostatic ImbalancesImbalances

Classification of BonesClassification of Bones

Long: longer than wideLong: longer than wide

Short: roughly cube-Short: roughly cube-shapedshaped

Flat: flat and slightly Flat: flat and slightly curvedcurved

Irregular: everything elseIrregular: everything else

Bone is always changingBone is always changing

Fetus skeleton is a cartilage Fetus skeleton is a cartilage template, replaced by bonetemplate, replaced by boneOssification (bone formation) Ossification (bone formation) continues until about age 16 in continues until about age 16 in females and 21 in malesfemales and 21 in malesLong bones stop growing in Long bones stop growing in length when the epiphyseal plate length when the epiphyseal plate ossifiesossifies

Fetal SkeletonFetal Skeleton

Cartilage is replaced by boneCartilage is replaced by bone

Longitudinal vs Appositional Longitudinal vs Appositional growthgrowth

Bones continue to change or Bones continue to change or remodel because of:remodel because of:

Hormones: growth and Hormones: growth and sexsex

Stresses and gravity Stresses and gravity (femur is replaced every 6 (femur is replaced every 6 months)months)

Body’s need for calciumBody’s need for calcium

Types of bone cells:Types of bone cells:

Osteoblasts: Bone-forming cells Osteoblasts: Bone-forming cells that secrete matrix, then get that secrete matrix, then get trapped in it and turn into:trapped in it and turn into:

Osteocytes: Mature bone cells Osteocytes: Mature bone cells imbedded in matrix of flexible imbedded in matrix of flexible collagen and hydroxyapatite (Ca collagen and hydroxyapatite (Ca salt)salt)

Bone remodels due to Bone remodels due to osteoblasts and osteoclastsosteoblasts and osteoclasts

Osteoclasts: Osteoclasts: Bone destroying Bone destroying cells, secrete cells, secrete enzymes that enzymes that destroy matrix destroy matrix and break down and break down calcium for the calcium for the bloodblood

Balancing blood calciumBalancing blood calcium

Bone FracturesBone FracturesA break in a boneA break in a boneTypes of bone fracturesTypes of bone fractures– Closed (simple) fracture – break that Closed (simple) fracture – break that

does not penetrate the skindoes not penetrate the skin– Open (compound) fracture – broken Open (compound) fracture – broken

bone penetrates through the skinbone penetrates through the skin

Treatment: closed or open (surgery) Treatment: closed or open (surgery) reduction and immobilization (cast)reduction and immobilization (cast)– Reduction = Realignment of the boneReduction = Realignment of the bone

Types of FracturesTypes of Fractures

Repair of fracturesRepair of fractures

Hematoma (blood-filled swelling) is formedBreak is splinted by fibrocartilage to form a callusFibrocartilage callus is replaced by a bony callusBony callus is remodeled to form a permanent patch

Steps in healing of fracturesSteps in healing of fractures

Bone ProblemsBone Problems

Osteoporosis: bone mass is lost Osteoporosis: bone mass is lost resulting in porous bones that resulting in porous bones that are easily broken, common in the are easily broken, common in the elderlyelderly

OsteomalaciaOsteomalacia

Softening of Softening of bones due to bones due to lack of calciumlack of calcium

Called rickets Called rickets in childrenin children

Paget’s DiseasePaget’s DiseaseAbnormal growth Abnormal growth and resorption of and resorption of bonebone

Possibly caused by Possibly caused by a virusa virus

Mostly affects hips, Mostly affects hips, shoulders and shoulders and vertebraevertebrae

Spinal curvaturesSpinal curvatures

Scoliosis: lateral curvatureScoliosis: lateral curvature

Lordosis: “swayback”, Lordosis: “swayback”, common in pregnant women common in pregnant women and “beer bellies”and “beer bellies”

Kyphosis: “humpback”, Kyphosis: “humpback”, common in osteoporosiscommon in osteoporosis

X ray of osteoporosisX ray of osteoporosis

X Ray QuizX Ray Quiz