Chapter 22 - Skeletal Muscle

Question 1

two types of skeletal muscle fibers

Answer 1

I: slow-twitch (endurance)
II: fast-twitch (power)

Question 2

myotrauma

Answer 2

injury to muscle or tendon (strain) –stretching or tearing

Question 3

symptoms of muscle strain

Answer 3

pain
redness or bruising
limited mobility
muscle weakness

Question 4

how do skeletal muscles repair themselves?

Answer 4

satellite cells

Question 5

how long does it usually take for muscle strains to heal?

Answer 5

8-10 weeks

Question 6

myalgia

Answer 6

muscle pain

Question 7

muscle tests

Answer 7

-biopsy
-electromyography (action potential)
-lab tests (creatine kinase) *increased levels indicate muscle disorder

Question 8

myopathic vs. neurogenic

Answer 8

myopathic: muscle is affected
neuropathic: motor neuron affected

Question 9

myopathy

Answer 9

muscle fibers don’t function for any one of many reasons – results in muscle weakness

Question 10

acquired myopathy :

Answer 10

muscle weakness from:
infections
inflammation
endocrine/metabolic
alcohol

Question 11

hereditary/genetic myopathy:

Answer 11

muscle weakness from:
mutations in genes coding for parts of a muscle

Question 12

inflammatory myopathy

Answer 12

muscle weakness from inflammation from another disease

Question 13

muscular dystrophies

Answer 13

group of disorders that cause degeneration of skeletal muscle fibers

Question 14

is muscular dystrophy myopathic or neuropathic

Answer 14

myopathic

Question 15

what are skeletal muscle fibers replaced by in muscular dystrophy disorders?

Answer 15

fat and fibrous tissue

Question 16

where do muscular dystrophies typically occur?

Answer 16

extremities, shoulders, and heart – can lead to paralysis

Question 17

most common type of muscular dystrophy

Answer 17

Duchenne (X-linked, recessive)

Question 18

is duchenne muscular dystrophy more common in men or women?

Answer 18

men

Question 19

a mutation in a gene that encodes ____ is the cause for duchenne MD

Answer 19

dystrophin

Question 20

when do manifestations of duchenne MD begin?

Answer 20

3 years old; loss of ambulation between 8-12

Question 21

main manifestation of duchenne MD?

Answer 21

enlarged calves (pseudo-hypertrophy); it’s not muscle, but fat and scar tissue
-slow motor development
-progressive wewkness
-clumsy, fall a lot
-sitting and standing difficult

Question 22

life span of someone with Duchenne MD

Answer 22

12-20; die from respiratory insufficiency or pneumonia

Question 23

chronic inflammatory myopathy symptoms

Answer 23

-progressive muscle weakness
-elevated CK levels
-systemic inflammation (CRP)

Question 24

types of chronic inflammatory myopathy

Answer 24

polymyositis: muscle only; lymphocyte infiltration
dermatomyositis: rash of eyelids, face, upper chest

Question 25

metabolic myopathy

Answer 25

metabolic disease causing muscle weakness

Question 26

McArdle's Disease

Answer 26

autosomal recessive disease that is a defect of myophosphorylase (break down glycogen) *glycogen storage disease

Question 27

symptoms of McArdle's disease

Answer 27

exercise intolerance painful muscle cramps myoglobinuria

Question 28

rhabdomyolysis

Answer 28

dissolving of skeletal muscle

Question 29

etiology of rhabdomyolysis

Answer 29

damaged skeletal muscle cells leak myoglobin and K+ into plasma which is filtered through the glomerulus and cause orange/brown urine color

Question 30

complications of rhabdomyolysis

Answer 30

nephrotoxicity - acute renal failure tubular obstruction

Question 31

third spacing

Answer 31

fluid sequestration in damaged tissue --> dehydration --> decreased blood flow to kidneys

Question 32

what is myasthenia gravis

Answer 32

autoimmune disease failure of neuromuscular transmission//connection (nerve cell can't connect to muscle correctly)

Question 33

etiology of myasthenia gravis

Answer 33

blockage and destruction of acetylcholine receptors

Question 34

what is myasthenia gravis characterized by?

Answer 34

muscled weakness that is aggravated by repeated contraction

Question 35

which muscle is typically affected with myasthenia gravis?

Answer 35

muscle with small motor units -- ocular muscles can progress to facial muscles, limbs, and respiratory system

Question 36

diagnostic testing of myasthenia gravis

Answer 36

tensilon test EMG serum assay

Question 37

treatment for myasthenia gravis

Answer 37

-immunosuppressives, cholinesterase inhibitors -thymectomy

Question 38

rhabdomyoma

Answer 38

rare BENIGN tumor of striated muscle

Question 39

rhadomyosarcoma

Answer 39

rare malignant tumor of striated muscle; more common in head, neck; more common in children

Question 40

paralysis types

Answer 40

flaccid: reduced muscle tone; lower motor neuron spastic: over toned muscle, hyperirritable nerves

Question 41

quadriplegia (tetra)

Answer 41

above 1st thoracic; all 4 limbs

Question 42

paraplegia

Answer 42

below 1st thoracic; legs

Question 43

hemiplegia

Answer 43

one sided paralysis

Question 44

hemiparesis

Answer 44

one sided weakness