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define hypertrophy
- Increase in quantity of actin + myosin filiments
- Enlarges muscle fibers
- Takes 6-10 weeks
- Caused by strong contractions
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Define atrophy
- Partial or complete wasting away of part of body
- Breakdown + reabsorption of tissues
- Can be normal or pathological
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Define muscle atrophy
- Total muscle mass decreases
- Loss of strength
- Due to bedrest / cast
- Reversed with excersize unless severe (cachexia)
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State diseases which lead to muscle atrophy
- AIDS and Cancer
- Congestive heart failure
- Liver disease
- Sarcopenia
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Discuss sarcopenia
- A gradual decrease in the ability to maintain skeletal muscle function and mass during aging
- Unknown cause
- Failure of satellite cells and growth factor
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What is Astemizole?
- Second generation anti-histamine drug
- Prevents muscle atrophy
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My name is Astemizole, and I am given...
To patients who have become bed-ridden
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Differentioate between upper and lower motor neurons
- Upper:
- - cortex to cranial nerve nucleus OR anterior horn
- - lesions associated with spastic paralysis / hypertonicity
- Lower:
- - cranial nerve nucleus OR anterior horn to skeletal muscle
- - lesions associated with falccid paralysis / hypotonicity
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Define neuropathy and its classifications
- Pathological process affecting peripheral nerves
- Classicfications: mononeuropathy (one nerve affected), polyneuropathy (many nerves affected), radiculopathy (nerve root affected)
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Define motor neuron diseases and its effect
- Group of neurological disorders that destroy motor neurons
- Result in loss of control of voluntary activity i.e. speaking, walking, breathing, swallowing
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Discuss spinal muscle atrophy (inheritance, effect, cause, symptoms, subtypes)
- Inheritance: genetically inherited – autosomal recessive
- Effect: Degeneration of anterior horn cells in spinal chord
- Symptom: symmetric proximal muscle weakness
- Cause: deletion of SMN1 gene
- Subtypes:
- - Type 1: severe hypotonia, presents in weeks, no sit no walk, respitory failure within 2 years
- - Type 2: proximal muscle weakness before 18 months, sit but no walk, survial past 4 years
- - Type 3: proximal muscle weakness before 2 years, can walk, survival past 40 years
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Discuss Myasthenia gravis (classification, types, presentation, effects, characteristics)
- Classifiaction:
- - Autoimmune disease
- - Junctionopathy
- 2 types:
- - Seropositive – anibodies agaisnt NAchR at NMJ’s
- - Seronegative – antibodies against Muscle Specific Protein Kinase
- Presentation:
- - First peak in 3rd decade
- - Second in 6th decade
- - Initially presents as ocular muscle weakness (ptosis and diplopia)
- Progression:
- - Craniocaudal
- Effect:
- - Fatigue of voluntary muscles
- - Shortness of breath
- - Characteristics:
- - Worsen in exertion
- - May come and go
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Discuss diagnosis of MG
- Tensilon (may cause hypotension and arrythmias)
- Ice test
- AchR antibodies
- EMG (repetetive nerve stimulation)
- MuSK antibodies
- Chest MRI (for thymic tumors)
- Brain MRI
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Discuss Lambert Eaton Myasthenic-myopathic syndrome (LEMS)
- Antibodies against calcium channels
- Inhibits Ach release at NMJ
- Rarely associated with small cell carcinoma of bronchus
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Define myopathy
Any condition related to muscle defects; affects muscle function
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Discuss Malignant Myperthermia (definition, inheritance, characteristic, treatment, cause, tests, pathophysiology, symptoms)
- Genetic myopathy that presents when patient is under anasthesia
- Inheritance: autosomal dominant
- Characteristics: Triggered by volatile anasthtic (halothane) or muscle relaxant (suxamethonium)
- Treatment: Using other relaxants (Dantroline) and improved monitoring
- Tests: Caffein-halothane contracture test on fresh muscle biopsy
- Cause: mutation in RyR1 gene
- Pathophysiology: MASSIVE release of Ca+ from SR
- Symptoms: Rigidity, hypoxemia, tachycardia, fever, increased serum creatine kinase,
- Warning: Symptoms may be clouded by Sepsis
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Define dystrophy
Any condition of abnormal develoment, usually due to malnutrition
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Discuss muscular dystrophy and genetic and heredatory disease
- Caracteristics:
- - Progressive skeletal muscle weakness
- - Muscle protein defects
- - Death of tissue
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Discuss Duchenne Muscular dystrophy (inheritance, presentation, effects, progression, cause)
- Most severe form of muscular dystrophy
- Inheritance: X-linked
- Presentation: kids apear normal at birth; symptoms at 5-7 i.e. toe walking
- Effects: difficulty running, climbing stairs, lordosis; Pseudohypertrophy, gower’s sign
- Progression:
- - 8-12 yo: wheelchair bound
- - late teens: arms affected
- - 20’s: suprainfections i.e. pneumonia
- Cause:
- - mutations in dystrophin gene
- - absence of dystrophin
- - no connectivity between ECM and actin+myosin
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Discuss fratures of a muscle biopsy taken in a patient with Duchenne Muscular dystrophy
- Variable fiber size
- Hypercontracted muscl fibers
- Immature muscle fibers
- Degenration of muscle fibers
- Dystrophen is absent
- Reduced sarcoglycan and aquaporins
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