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Locomotor 2 > Muscles in Health and Disease > Flashcards

Muscles in Health and Disease Flashcards

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1
Q

What is muscle important for

A
  • Store for intracellular ions such as potassium and small amounts of calcium in the dissolved water
  • Important for heat production
  • Glucose handling
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2
Q

How much body weight and store of water is muscle

A

40% of body mass

80% of water

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3
Q

what are the different types of muscle

A

skeletal muscle/stirated
cardiac muscle
smooth muscle

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4
Q

what is sacromere made up of

A

actin and myosin

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5
Q

describe skeletal muscle

A
  • stripy appearance

- nuclei in the periphery

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6
Q

in skeletal muscle what is central nuclei are marker of

A

muscle regrowth - new muscle formation

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7
Q

describe the nerve supply to the skeletal muscle

A

LMN – ventral horn of the spinal cord, exit from the ventral root, enter from the peripheral nerves, motor neurone then spreads out to innervated 5 and up to 100 or more muscle fibres

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8
Q

what happens when you lose a single motor neurone innervation

A

Affects all muscle fibres innervated by that motor neurone

  • in about 2 months the muscles will atrophy
  • Small angulated muscle fibres
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9
Q

what is a motor unit

A

all muscles fibres innervated by that Motor neurone

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10
Q

if only one single motor neurone looses its innervation what can other neurones od

A

Sprouting of remaining motorneuron axons synapse with denervated fibres.

Motor units enlarge and rather than been scattered they appear as groups.

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11
Q

What is fibre type determined by

A

Fibre type determined by primary motor neuron

- motor unit fibres all same fibre time

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12
Q

describe what happens in motor neurone disease

A
  • In conditions where you have continuous loss of motor neurons it comes to the point where more of the motor neuornes have died and the remaining motor neurone have tried to asses the muscle fibres that are being innervated and the motor unit is larger

If that motor nuerone then dies then a lot of muscles loose innervation

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13
Q

what is infant hypotonia

A
  • infants muscles are hypotonic

- get a floppy hypotonic baby

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14
Q

what can cause infantile hypotonia

A
  • myopathic reason

- most of the fibres are small with a few massive hypertrophic fibres

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15
Q

What are the two types of infantile hypotonia

A
  • Large type 1 muscle fibres (paler) = Slow type 1 fibres aerobic metabolism mainly
  • Small type 2 muscle fibres (darker) = Fast type 2 fibres mixed aerobic and anaerobic metabolism
  • Small fibres = type 1 fibres = Slow type 1 fibres aerobic metabolism mainly
  • Type 2 fibres are normal to larger in diameter. = Fast type 2 fibres mixed aerobic and anaerobic metabolism
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16
Q

what is the good thing about infantile hypotonia

A
  • usually sort itself out but no lasting problems

- but may not be able to do lots of exercise as they may fatigue more easily

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17
Q

What are the two types of skeletal muscle

A

Slow type 1 fibres aerobic metabolism mainly

Fast type 2 fibres mixed aerobic and anaerobic metabolism

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18
Q

What is sarcopenia

A

the loss of skeletal muscle mass and strength as a result of ageing.

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19
Q

How much skeletal muscle mass is lost after the age of 50 years

A
  1. 5 – 1% loss after age of 50 years

- But up to 3% - 5% if physically inactive

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20
Q

what happens to bone mass and muscle mass with ageing

A
  • loss muscle mass = sarcopenia
  • loose bone mass = osteoporosis
  • muscle strengths is lost therefore impaired balance
  • decreased bone strength
  • these things contribute to fracture
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21
Q

What are general symptoms of muscle disorders

A 
Pain and weakness
Twitching and cramps
Muscle atrophy and contractures
Family history
Drug exposure
Endocrine disorders
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22
Q

How do you diagnose muscle disorders

A

Biopsy

EMG - electromyography

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23
Q

What are the two inflammatory myopathies and what is the difference

A

Polymyositis

Dermatomyositis (only difference is with this one you get a skin rash)

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24
Q

where do inflammatory myopathies start

A

Starts at the periphery of the muscle fascile

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25
describe the characteristics of inflammatory myopathies
Associated with microbial infection Autoimmune Proximal muscle weakness (around shoulder and around the hip) 5-10 million per year 2:1 prevalence in females 40-60 years
26
what are the clinical features of inflammatory myopathies
Symmetrical involvement of large proximal muscles of shoulders, arms and thigh
27
how do you diagnose inflammatory myopathies
Serum creatine kinase elevated = marker of muscle damage EMG - typical irritability in 90% Biopsy most definitive - Variation in fibre size - Central nuclei - Necrosis and regeneration - Infiltrate of inflammatory cells (lymphocytes)
28
What is found in the biopsy in inflammatory myopathies
Lymphocytes surround and invade individual muscle fibres (CD8+ T lymphocytes) with some macrophages to remove necrotic fibres - damaged muscle fibres - centrally located nuclei where there is regeneration
29
What does the Dermatomyositis rash look like
Dermatomyositis rash is typically purplish in colour and often has a streaky pattern. Heliotrope rash over eyelids with oedema
30
in inflammatory myopathies what antibody is found positive
ANA positive in 90% of cases | - anti-Jo1 antibody (20-40% of cases)
31
what is subcutaneous calcifications
Autoimmune connective tissue disease | Calcification in muscles and in skin
32
what is the treatment of inflammatory myopathies
Corticosteriods - High dose 1mg/kg prednisone per day - Maintained until creatine kinase normal - If stopped early flares in disease and difficult to control - Azathioprine - Methotrexate
33
what is the survival rate for inflammatory myopathies
5 year survival = 80% 8 year survival = 73% Death from malignancy, infection and pulmonary involvement More likely if anti-Jo 1 positive
34
what is inclusion body myositis
- most common muscle disease of the elderly - poor prognosis - loss of specific muscle groups
35
what is the must common muscle disease of the elderly
inclusion body myositis
36
what is inclusion body myositis more common in
males
37
what is elevated in inclusion body myositis
Mild elevation in creatine kinase
38
what muscles are affected by inclusion body myositis
Finger and wrist flexors more than extensors and shoulder abductors Knee extensors more than hip flexors
39
what problems are associated with inclusion body myositis
Associated polyneuropathy Loss of quadriceps reflex Dysphagia
40
what does the biopsy of inclusion body myositis
Fibres contain empty vacuoles and clumps of cellular material that contain amyloid like material (congo red). Filamentous inclusions of IBM have optical properties of amyloid and contain beta amyloid, hyperphosphorylated tau, apolipoprotein E, presenillin 1, prion protein, and other proteins that accumulate in muscle
41
give example of x linked muscular dystrophies
Duchenne and Becker muscular dystrophies Limb girdle muscular dystrophy Emery-Dreifuss muscular dystrophy
42
What are muscular dystrophies
Progressive genetically linked degenerative myopathies - Effecting the cytoskeletal proteins that maintain the integrity of the muscle membrane and the connection with the extracellular matrix outside the cell
43
name some autosomal recessive muscular dystrophies
Limb girdle muscular dystrophy Emery-Dreifuss muscular dystrophy
44
name some autosomal dominant muscular dystrophies
Facioscapulohumeral muscular dystrophy Limb girdle muscular dystrophy Emery-Dreifuss muscular dystrophy Oculopharyngeal muscular dystrophy
45
name the muscle areas that are affected by - Duchenne and Becker - Limb Girdle - Facto-scapulo humeral - emery- Dreifuss
Duchenne and Becker - arm - plantar flexors - thigh Limb Girdle - thigh - shoulder region Facto-scapulo humeral - face - shouter region - plantar flexors emery- Dreifuss - shoulder and arm - plantar flexors
46
What is the most common muscular dystrophy
- Duchenne muscular dystrophy is the most common
47
what happens in Duchenne muscular dystrophy
It is the completely loos of dysphotrin protein, Usually connects the contractile apparatus to the ECM and maintains the integrity of the muscle membrane
48
How many people get Duchenne muscular dystrophy
20-30 per 100,000 males per year (1:3,500 male babies)
49
what muscles are affected by Duchenne muscular dystrophy
Proximal muscle weakness during first 2 years
50
describe duchen muscular dystrophy and its progression
Continuous slow decline - Unable to walk by 7-12 years - Death usually mid twenties to early thirties - heart is affected therefore they often die from cardiomyopathy
51
What happens to creatine kinase in Duchenne muscular dystrophy
severely elevated
52
describe the biopsy of Duchenne muscular dystrophy
- Fibre size variability - Endomysial fibrosis - Degenerating muscle fibres undergoing myophagocytosis - repeated degeneration and regeneration of muscle fibres therefore you end up depleting the muscle stem cells - eventually you loose the muscle fibres and replace it with fibrotic or fat
53
what is Beckers disease
- Dysphotrin protein is shortened and is not as good as protecting the muscle membrane but still works - Therefore it is milder
54
What is the treatment for Duchenne muscular dystrophy
- corticosteroids
55
what can corticosteroids induce
Type 2 fibre atrophy - Has implications on person being able to move - Type 1 is for posture whereas type 2 is for movement and generating force- has influence of ability of individual to move - Take them off corticosteroids and this fibre goes back to its original size therefore the atrophy is not permanent
56
what can stains lead to
Approx 10% of patients Rhabdomyolysis - myoglobin clogs the kidneys and can cause potential renal filature
57
how can alcohol damage the muscle
- have muscle atrophy - Chronic - slow progressive proximal weakness - Acute - single heavy session
58
What is fibromyalgia
- connective tissue disorder | - Widespread muscle pain
59
describe fibromyalgia diagnostic criteria
Both sides of the body, above and below waist, in axial skeleton Combination of 11 or more of 18 specific tender points - 2kg of pressure applied
60
what is the trigger of fibromyalgia
Antipolymer antibodies | - 50% of patients positive
61
what is fibromyalgia associated with
Associated fatigue and sleep disturbance 30-60 year age group 80-90% patients female
62
describe the cycle of fibromyalgia
Muscle tension from daily stress leads to fatigue muscle stiffness and pain Pain leads to poor quality of sleep Sleep increases the stress levels and you ability to be able to cope with stress so you feel more pain and this leads round
63
what is the treatment of fibromyalgia
Tricyclic antidepressants - amitriptyline SSRIs - fluoxetine Exercise Complementary therapy

Locomotor 2 (30 decks)

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