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Dysfunction of the Skeletal System

Dysfunction of the Skeletal System. Homeostatic Imbalances and Bone Repair. Homeostatic Imbalances of Bone. Osteoporosis Arthritis Osteomalacia/Rickets Paget’s Disease. Homeostatic Imbalances of Bone (Osteoporosis). Normal matrix, but decreased bone mass Bone reabsorption > Bone deposit

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Dysfunction of the Skeletal System

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  1. Dysfunction of the Skeletal System Homeostatic Imbalances and Bone Repair

  2. Homeostatic Imbalances of Bone • Osteoporosis • Arthritis • Osteomalacia/Rickets • Paget’s Disease

  3. Homeostatic Imbalances of Bone(Osteoporosis) • Normal matrix, but decreased bone mass • Bone reabsorption > Bone deposit • Osteoclast more active than osteoblasts • Porous, light, fragile bones • Spongy bone most vulnerable Ex. Compression fractures of vertebrae, neck of femur

  4. Homeostatic Imbalances of Bone(Osteoporosis) • Bone health maintained by hormones • Estrogen: restrain osteoclasts and promote bone deposition • Greatest Risk Factors: • Older, post-menopausal women • Petite body • Insufficient load-bearing exercise • Diet poor in Calcium, Vit D and protein • Thyroid disease • Diabetes • Smoking (reduces estrogen, promotes weight loss)

  5. Homeostatic Imbalances of Bone(Osteoporosis) • Prevention: focuses on reversing risk factors • dietary supplements • Load bearing exercise • * hormone (estrogen) replacement therapy (HRT) • Alternative Therapies: • Alendronate: drug reduces osteoclast activity • Selective Estrogen Receptor Modulators (SERMS): mimic estrogen’s benefits without risks associated w/ HRT • Statins: cholesterol medication that increases bone density as side effect. • Soy protein: supplements diet, contain estrogen-like compounds *Associated risk of heart attack, stroke, breast and uterine cancer

  6. Homeostatic Imbalances of Bone(Osteoporosis) • Bone Density Test • Special X-rays used to measure mineral content of bone. • Repeated every 2–3 years Bone Density Scan of a NORMAL menopausal woman Color Ranges: Blue/purple, least dense to white, most dense

  7. Homeostatic Imbalances of Bone(Arthritis) • > 100 types • inflammation of joint, causing pain • Often cartilage is broken down • Rheumatoid arthritis • autoimmune • body’s own cells of IS attack soft tissue around joint.

  8. Homeostatic Imbalances of Bone(Osteomalacia/Rickets) • “Soft bones”: • bones w/ matrix and structure, but minimal calcium • Insufficient Ca and Vit D diet • Osteomalacia: adult form • Reversible with dietary changes. • Rickets: youth form • more severe: bones still developing • causes bowed legs and deformed pelvis, skull, ribs • Abnormally long bones due to lack of calcification of epiphyseal plate • Bone deformities permanent.

  9. Homeostatic Imbalances of Bone(Paget’s Disease) • Disorganized resorption and formation of bone • High spongy bone: compact bone ratio • Reduced mineralization • Osteoclast activity < Osteoblast activity causing bone thickening Fractured right femur of Paget’s patient due to weakening of bones

  10. Classification of FracturesI. Position • Non-displaced: bone ends in alignment • Displaced: bone ends out of alignment

  11. Classification of FracturesII. Breakage • Complete: Fractures break all the way through • Incomplete: partial fracture

  12. Classification of FracturesIII. Orientation • Linear: fracture runs parallel along the axis • Transverse: fracture is perpendicular to the axis Linear Transverse

  13. Classification of FracturesIV. Skin Penetration Simple: Fracture does not pierce skin Compound: Fracture pierces skin

  14. Classification of FracturesAppearance • Comminuted: Bone fragments into multiple pieces • Compression: crushed bone

  15. Classification of FracturesAppearance • Spiral: ragged break due to twisting forces • Depressed: Bone portion pushed inwards

  16. Classification of FracturesAppearance • Greenstick: incomplete fracture; Only one side of the shaft breaks; the other side bends.

  17. Classification of FracturesPosition • Epiphyseal: separation of epiphysis from diaphysis along epiphyseal plate

  18. Treating Fractures • Reduction: realignment of broken bone ends • Closed/External: hands used to coax bones back to realignment • Open/Internal: surgical realignment of bone ends secured together by pins or wires • Immobilization with cast or traction

  19. Bone Repair • Osteoblasts convert cartilage to spongy bone • Blood clots • Bone cell death • inflammation • Capillary growth • Phagocytes eat cell debris • Fibroblasts bridges gap with collagenFIBER • Chondroblasts secrete CARTILAGE matrix to create framework for bone formation. Cartilage later calcifies and dies.

  20. Bone Lengthening Surgery • Lengthens bone up to 3 in • Procedure: • Breaking bones of leg (tibia/fibula or femur) • Bone moved apart 1 mm/day w/ external device • Body regenerates new bone to fill-in space as matrix tears • Repair deformities • Cosmetic Reasons • (Extreme make-over)

  21. Bound Feet in China • Small “lotus” feet (< 4 in.) = symbol of beauty in China up until 1920’s • Young girls’ feet broken and bent so toes bound under foot

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