Skeletal mm Pathology (7) Flashcards

1
Q

what is sarcoplasmic hypertrophy

A

Primary due to increased glycogen storage

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2
Q

What do satellite cells do

A

Facilitate growth, maintaenance and repair of damaged skeletal mm tissue

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3
Q

What is the role of fibroblast growth factor

A

proliferation and differentiation of satelite cells, leading to skeletal mm hypertrophy (amount released is proportional to degree of mm trauma)

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4
Q

what is rhabdomyolysis and what does it release into circulation

A

Widespread acute necrosis of skeletal mm fibres

–releases into circulation systolic proteins such as myoglobin (crash-syndrome)

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5
Q

What is trichinosis due to and what does it cause

A

Trichinella spiralis inf

-mm pain, periorbital edema, splinter hemorrhages

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6
Q

Clostridium tetani- transmission, s/s

A

trans- spores in soil enter body, 2 day incubation

ss- begins w mm stiffness in jaw, lockjaw, slightest stim causes generalized, painful mm contractions

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7
Q

What is duchennes muscular dystrophy characterized by

A

Characterized by progressive degen of mm particularily those in pelvis/shoulder girdles

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8
Q

Genetics of ducheenes mm dystrophy and rate

A

X linked recessive

1:3500 male births

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9
Q

Pathogenesis of ducheene dystrophy

A
  • relentless necrosis of mm
  • # of mm cells decreases progressively
  • replaced by fibroadipose tissue (pseudohypertrophy)
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10
Q

Dx of ducheene mm dystrophy and when is it evident clinically

A

Dx: PCR detection of abnormal DNA from leukocytes, increased serum kinase

clinical- not detectable during first year (evident by 3/4 years)

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11
Q

What causes death in ducheene mm dystrophy

A

complications of respiratory insufficiency caused by mm weakness
-cardiac arrhythmia owing to myocardial involvement

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12
Q

Differences bw ducchenes and becker

A

becker- typically milder/later onset, truncated protein

ducheene: absence of dystrophin

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13
Q

Myotonic dystrophy- rate, genetics

A

Mc adult mm dystrophy

autosomal dominant
-trinucleotide repeat disorder on chromosome 19 (on myotonic dystrophy pro kinase gene)

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14
Q

s.s of myotonic dystrophy

A

-testicular atriphy, glu intolerence, mm wasting, cardiac defects

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15
Q

what is myasthenia gravis and what does it affect

A

antibodies to the Ach receptor at the myoneural junction (destroy via complement system)

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16
Q

What does myasthenia gravis cause

A

-impaired signal trans (mm weakness, fatigue)

17
Q

What is lambert-eaton syndome

A

-Paraneoplastic disorder where igG autoanibodies traget voltage sensitive calc channels expressed in motor nerve terminal and in cells of lunch cancer

18
Q

What does paraneoplastic disorder cause

A

manifests as mm weakness, wasting and fatigability of prox limbs/ trunk

19
Q

Pathological changes in rhabdomyolysis

A

an active, non inflammatory myopathy w scattered necrosis of mm fibres

-causes mm to be swollen, tender and profoundly weak

20
Q

s/s of rhabodomyolosis

A
  • pain (first sym)
  • dark urine
  • renal insuffiencieny
  • creatine kinase elevation
21
Q

What is crush syndrome

A

traumatic rhabdomyoloysis due to natural disaters etc

22
Q

what is denervation

A

lesions of LMN

-progressive invariably atrophy of a skeletal mm fibre due to interrupted connection w LMN

23
Q

What is spinal muscular atrophy and what is it due to

A
  • 2nd mc letal autosonmal recessive disorder after cystic fibrosis
  • Surviva mm neuron gene (SMN1) is absent in virtually all cases
24
Q

what is steroid myopathy due to and causes

A
  • Due to corticosteroid therapy (large doses)
  • serum kinase not always elevated
  • severe mm weakness
25
What does statin induced myopathies cause, blood markers
-prox mm weakness occurring during or after tx w statins - elevated creatine kinase - persistece of weakness and elevated CK despite discontinuation
26
What are the 2 noninfectious inflammatory myopathies and what characterizes them
-group of immune mediated disorders w symetrical mm invlvment 1. Polymyositis 2. Dermatomyositis
27
Polymyositis- age, gender, risks
Female dominant - black pop - 40-60 risk- increased risk of malignant neoplasms
28
pathogeneis of polymyositis
-cytotoxic CD8 t cells and CD4 cells activate macrophages to damage unidentified antigens in myocyte fibres in skeletal mm
29
triggers of polymyositis
triggers for t cell response may be associated with HIV, Coxsackie virus B
30
Clincial findings of polymyositis
- constitutional signs - symetrical prox weakness - dysphagia - respiratory difficulties **mm atrophy not feature**
31
lab findings of polymyositis
- Serum CK and aldolase increased | - Serum ANA increased
32
Dermatomyositis- etiology +pathogenesis
activated cd4 t cells primarily target the capillaries in skeletal mm -antibodies and complement are involved in the capillary damage
33
Clinical findings of dermatomyositis
mm complaints are similar to those in polymyositis **Atrophy is prominent fx** - reddish-purple papules called gottron patches are noted over knuckles and PIPs - purple/red eyelid discoloration occurs