Quiz 4 Muscles Flashcards
Disuse atrophy
can be masked because increased fat develops between muscle fibers
neurogenic atrophy
loss of muscle mass as a result of damaged nerve supply
most common muscular dystrophy
Duchenne’s
Duchenne’s
due to defective gene on X chromosome that leads to inability to produce one of the proteins in skeletal muscle cell membrane (dystrophin)
What is the protein that is lacking in Duchenne’s
dystrophin
hist of muscular dystrophy
tissue becomes disorganized, and concentration of dystrophin is decreased
early Duchenne’s vs late
muscle fibers atrophy and fibrose due to excessive ca and increased reactive oxygen species. Fibrotic cells then degenerate and are replaced by fat
neuromuscular disease leading to fluctuating muscle weakness and fatigability
myasthenia gravis
myasthenia graves weakness is caused by what?
circulating antibodies that block acetylcholine receptors at post-synaptic neuromuscular junction and inhibit stimulative affect of acetylcholine
what muscles are affected in myasthenia gravis?
eye muscles, facial expression, chewing, talking, swallowing
what thymic abnormalities are related to males vs females with myasthenia gravis?
females: thymic hyperplasia
males: thymoma
hist of myasthenia gravis
large collections of lymphocytes and necrotic muscle fibers that appear pale and atrophic
progressive muscle weakness in upper arms and upper legs
Lambert-Eaton syndrome
Lambert-Eatons syndrome is associated with what?
small cell lung cancer
what receptors are affected in Lambert-Eaton syndrome?
ab to presynaptic ca channels in neuromuscular junction
- prevents normal function of calcium channels which inhibits release of acetylcholine
What are the three inflammatory myopathies?
dermatomyositis
polymyositis
inclusion body myositis
dermatomyositis
B and T cells
perifascicular muscle fiber atrophy
heliotrope purple rash around eyes and malar area
Gottron’s sign
Gottron’s sign
purple red papular rash over dorsal hands
associated with dermatomyositis
polymyositis
macrophage in muscles cells
no skin involvement
cytotoxic T8 lymphocytes in hist
inclusion body myositis
amyloid protein and inclusion bodies
inclusions in cells are pathonomonic
most common benign muscle tumor
rhabdomyoma
- usually on head or neck
most common malignant soft tissue tumor in children
rhabdomyosarcoma
hist of rhabdomyosarcoma
increased mitotic figures, darker staining nucleus
