Skeletal Muscle

Question 1

Red, slow twitch fibers

for endurance-resist fatigue

Answer 1

type 1 fibers

Question 2

white, fast twitch fibers
strength training
Selectively destroyed in prolonged steroid use

Answer 2

type 2 fibers

Question 3

• X-Linked
• Increase in CK
• Pelvic and shoulder girdle weakness
• Mutation in dystrophin gene
• Macrophages invade and engulf necrotic material
• muscles appear large because theyre replaced by fat (pseudohypertrophy)

Answer 3

Duchennes MD

Question 4

Mild from of Duchennes

Dystrophin is truncated

Answer 4

Beckers MD

Question 5

• Most common form of adult MD
• Autosomal Dominant
• atrophy of type 1 fibers, hypertrophy of type 2 fibers
• circumferentially oriented sarcomeres
• cataracts, testicular atrophy, GI issues, balding, arrythmias

Answer 5

myotonic dystrophy

Question 6

• Mutation on chromosome 19-ryanodine receptor
• malignant hyperthermia
• rhabdomyolsis
• hypotonia and decreased DTR
• central pallor, target formations

Answer 6

Central Core Disease

Question 7

• Red, Rod like inclusions in sarcoplasm
• Congenital hypotonia and kyphoscoliosis
• Peripheral Inclusions

Answer 7

Rod/Nemaline Myopathy

Question 8

• Proximal Muscle weakness
• mutated dynamin 2
• Bilateral ptosis
• centrally located nucleus

Answer 8

central nuclear myopathy

Question 9

Symmetrical proximal muscle weakness
Increased serum muscle enzymes
non-suppurative inflammation

Answer 9

General features of all inflammatory myopathies

Question 10

CD8+ infiltrate
MHC1 antigen expression
lung disease and raynauds
Responsive to steroids

Answer 10

Polymyositis

Question 11

Rimmed Vacuoles
Cytoplasmic inclusions-stain with congo red
Not responsive to steroids

Answer 11

Inclusion body myositis

Question 12

• Deposits IgG, IgM and complement in capillary walls
• B cell and CD4+ infiltrate
• Rash on upper eyelids (heliotrope)
• Perifascicular atrophy

Answer 12

Dermatomyositis

Question 13

• Muscle fatigue-worse throughout day
• autoantibodies to Ach receptor
• increased risk of thymoma
• ptosis, and diplopia

Answer 13

myasthenia gravis

Question 14

muscle weakness
wasting
fatigability of proximal muscles and trunk
Small cell lung cancer

Answer 14

Eaton Lambert Syndrome

Question 15

Acid Maltase deficiency
accum of membrane bound glycogen
severe hypotonia and areflexia

Answer 15

Pompe Disease

Question 16

Debranching enzyme deficiency
growth retardation
liver dysfunction

Answer 16

Cori Disease

Question 17

Myophosphorylase deficiency
severe cramping during exercise-cannot make lactate
Tx-avoid vigorous exercise
non-membrane bound glycogen

Answer 17

McArdle Disease

Question 18

• Proximal muscle weakness and atrophy
• Denervation and peripheral neuropathy
• Accum. of lipid in sarcoplasm outside mitochondria

Answer 18

Carnitine Deficiency

Question 19

• Paracrystalline inclusions on EM
• Can’t metabolize long chain fatty acids
• Pain after exercise with myoglobinuria

Answer 19

carnitine palmitoyltransferase deficiency

Question 20

• Ragged red fibers-accum of mitochondria

- Deficient in complex IV

Answer 20

Mitochondrial Disease

Question 21

opthalmoplegia
retinal pigment degeneration
cardiac arrythmia
ragged red fibers

Answer 21

kearns-sayre syndrome (one of the mitohondrial diseases)

Question 22

• myoglobin released into blood
• positive urine dipstick for blood
• no RBC’s on urinalysis
• acute renal failure
• can occur after influenza, alcoholism
• scattered necrosis, degeneration and regeneration

Answer 22

rhabdomylosis

Question 23

Target fibers
type grouping
atrophy
angular configurations of fibers
replacement of fibers by adipose tissue

Answer 23

Denervation

Question 24

• Floppy Baby
• infants show progressive weakness, on’t live past 1 year
• clusters of hypertrophied pale type 1 fibers

Answer 24

Werdnig Hoffman (late onset is kugelberg welander)

Question 25

• Type 2 fiber angular atrophy
• No increase in CK
• Usually related to chronic problem-being treated with steroids

Answer 25

Steroid myopathy