Quiz 4 Muscles

Question 1

Disuse atrophy

Answer 1

can be masked because increased fat develops between muscle fibers

Question 2

neurogenic atrophy

Answer 2

loss of muscle mass as a result of damaged nerve supply

Question 3

most common muscular dystrophy

Answer 3

Duchenne’s

Question 4

Duchenne’s

Answer 4

due to defective gene on X chromosome that leads to inability to produce one of the proteins in skeletal muscle cell membrane (dystrophin)

Question 5

What is the protein that is lacking in Duchenne’s

Answer 5

dystrophin

Question 6

hist of muscular dystrophy

Answer 6

tissue becomes disorganized, and concentration of dystrophin is decreased

Question 7

early Duchenne’s vs late

Answer 7

muscle fibers atrophy and fibrose due to excessive ca and increased reactive oxygen species. Fibrotic cells then degenerate and are replaced by fat

Question 8

neuromuscular disease leading to fluctuating muscle weakness and fatigability

Answer 8

myasthenia gravis

Question 9

myasthenia graves weakness is caused by what?

Answer 9

circulating antibodies that block acetylcholine receptors at post-synaptic neuromuscular junction and inhibit stimulative affect of acetylcholine

Question 10

what muscles are affected in myasthenia gravis?

Answer 10

eye muscles, facial expression, chewing, talking, swallowing

Question 11

what thymic abnormalities are related to males vs females with myasthenia gravis?

Answer 11

females: thymic hyperplasia
males: thymoma

Question 12

hist of myasthenia gravis

Answer 12

large collections of lymphocytes and necrotic muscle fibers that appear pale and atrophic

Question 13

progressive muscle weakness in upper arms and upper legs

Answer 13

Lambert-Eaton syndrome

Question 14

Lambert-Eatons syndrome is associated with what?

Answer 14

small cell lung cancer

Question 15

what receptors are affected in Lambert-Eaton syndrome?

Answer 15

ab to presynaptic ca channels in neuromuscular junction

- prevents normal function of calcium channels which inhibits release of acetylcholine

Question 16

What are the three inflammatory myopathies?

Answer 16

dermatomyositis
polymyositis
inclusion body myositis

Question 17

dermatomyositis

Answer 17

B and T cells
perifascicular muscle fiber atrophy
heliotrope purple rash around eyes and malar area
Gottron’s sign

Question 18

Gottron’s sign

Answer 18

purple red papular rash over dorsal hands

associated with dermatomyositis

Question 19

polymyositis

Answer 19

macrophage in muscles cells
no skin involvement
cytotoxic T8 lymphocytes in hist

Question 20

inclusion body myositis

Answer 20

amyloid protein and inclusion bodies

inclusions in cells are pathonomonic

Question 21

most common benign muscle tumor

Answer 21

rhabdomyoma

- usually on head or neck

Question 22

most common malignant soft tissue tumor in children

Answer 22

rhabdomyosarcoma

Question 23

hist of rhabdomyosarcoma

Answer 23

increased mitotic figures, darker staining nucleus