BIOL 207 Chapter Notes - Chapter 8: Muscular Dystrophy, Skeletal Muscle, Sarcolemma
Document Summary
Group of inherited muscle destroying diseases that appear during childhood. Muscles involved enlarge b/c of fats and connective tissue but muscle fibers atrophy (grow very weak) and degenerate. Sex linked recessive disorder mostly in males (1 in every 3600 births) Children become clumsy and fall a lot because of skeletal muscles weakening. Disease advances quickly (affects head and chest muscles) Death is can be b/c of respiratory failure. Caused by defective gene (dystrophin cytoplasmic protein links cytoskeleton to extracellular matrix and stabilize sarcolemma. Fragile sarcolemma tears during muscles contraction, allowing more calcium to enter which damages contractile fibers. Inflammatory cells (macrophages and lymphocytes accumulate in surrounding connective tissue resulting in muscle mass drop. No cure for dmd but immunosupresion drugs delay muscles deterioration. Age increase results in more connective tissue and decrease in muscle fibers. Age 30 sarcolepsy begins (gradual loss of muscel mass) Age 80- strength decreases by 50% as result of amount of skeletal muscle in body.