Week 1 Flashcards
What surrounds bundles of muscle fibres, entire muscle and individual muscle fibres?
- Perimysium
- Epimysium
- Endomysium
Give two features of red fibres (type I, slow twitch)?
- Large mitochondria
2. Increased myoglobin
Give two features of white fibres (type II fast twitch)?
- Small mitochondria
2. Large motor end-plates
Why are slow twitch fibres resistant to fatigue?
Greater ability to regenerate ATP
In type I muscle fibres - what colour is ATPase, pH 9.4?
Light
In type II muscle fibres - what colour is ATPase pH 9.4?
Dark
In the histological appearancde of a normal adult quadricep - what appearance is normal?
Checkerboard
In muscle dystrophies - what level is CK?
200-300 times the normal
In inflammatory myopathy - what level is CK?
20-30 times the normal
In neurogenic disorders - what level is CK?
2-5 times the normal
Give four features of dystrophic muscle changes?
- Variability in muscle fibre size
- Endomysial fibrosis
- Fatty infiltration and replacement
- Myocyte hypertrophy and fibre splitting
What does increased central nuclei, segmental necrosis, regeneration and ring fibres all suggest?
Dystrophic changes
Are muscular dystrophies inherited?
Yes
Give the inheritance and muscle affected in - Duchenne (DMD)
X-linked recessive
Pelvic girdle
Give the inheritance and muscle affected in - Becker (BMD)
X-linked recessive
Pelvic girdle
Give the inheritance and muscle affected in - Limb girdle (LGMD)
Autosomal recessive
Pelvic girdle
Give the inheritance and muscle affected in - Fascioscapulohumeral
Dominant
Face, shoulder girdle, arm
Give the inheritance and muscle affected in - Scapulohumeral
Autosomal recessive
Shoulder girdle, arm
Give the inheritance and muscle affected in - Oculopharyngeal
Dominant
External ocular and pharynx
Give the inheritance and muscle affected in - Myotonic dystrophy
Dominant
Face, respiratory, limbs
Give 4 pathological features of muscular dystrophies?
- Destruction of single fibres
- Prolonged
- Regeneration
- Fibrosis
When is DMD usually diagnosed?
2-4 years of age (die at 20)
What disease has proximal weakness of quadriceps and pelvic muscles, but pseudohypertrophy of calves - difficulty squatting?
DMD
Describe the mutation in DMD?
Mutations in dystrophin gene on long arm chromosome X
What does the dystrophin mutation result in (three things)?
- Alterations in anchorage of actin cytoskeleton to basement membrane
- Fibres liable to tearing
- Uncontrolled calcium entry into cells
Which disease has a later onset - DMD or Becker?
Becke
Describe the mutation in Becker MD?
Mutation in dystrophin, but lower grade version of DMD
What disease involves muscle weakness, myotonia and non-muscle features?
Myotonic dystrophy
What genes are affected in myotonic dystrophy?
Ch19 and Ch3
In adolesence myotonic dystrophy affects face and distal limbs - what does it affect later?
Respiratory
What are these histological features of: atrophy of type I fibres, central nuclei placement, ring fibres - prominent, fibre necrosis and fibrofatty replacement?
Myotonic dystrophy
Name two inflammatory myopathies that are autoimmune?
Polymositis
Dermatomyositis
What is a chronic inflammatory disease, more common in women and involves progressive muscular weakness, pain and tenderness?
Polymyositis
Give three features of polymyositis?
- Cell-mediated immune response to muscle antigens
- Endomysial lymphocytic infiltrate, invasion of muscle by CD8 cells
- Segmental fibre necrosis
What disease involves skin changes plus polymyositis, upper body erythema, swelling of eyelids with purple discolouration and occurs years/months before first symptoms of cancer?
Dermatomyositis
Give three pathological features of dermatomyositis?
- Immune complex and complement deposition within and around capillaries within muscle
- Perifascicular muscle fibre injury
- B-lymphocytes and CD4 + T cells > cf polymyositis
What class of diseases have stereotyped changes after nerve damage with subsequent re-innervation?
Neurogenic disorders of muscle
What conditions are there histological features of: small, angulated muscle fibres, target fibres, fibre type grouping and grouped atrophy?
Neurogenic disorders of muscle
What disease has progressive degeneration of anterior horn cells and denervation atrophy, fasciculation and weakness?
Motor Neuron Disease
What is the gene affected and inheritance of spinal muscular atrophy?
Inherited
Autosomal recessive
Ch5
What disease has four types, involves denervation of muscle and has degeneration of anterior horn cells in the spinal cord?
Spinal muscular atrophy
Name the disease that is autoimmune, has weakness, proptosis, fatigue and dysphagia, occurs in women 20-40 and 25% of patients have thymoma?
Myasthenia Gravis
What disease has breakdown of skeletal muscle including myoblobinuria, hyperkalaemia and necrosis?
Rhabdomyolysis
Give four outcomes of Rhabdomyolysis?
- Acute renal failure
- Hypovolaemia & hyperkalaemia
- Metabolic acidosis
- Disseminated intravascular coagulation
What variety of disorders are multi-system including joints, skin and subcutaneous tissues, are common in women, immunologicaly abdnormalities are common and they usually respond to anti-inflammatory drugs
Connective Tissue Disorders
Name a connective tissue autoimmune multisystem disorder?
SLE
What antibodies are looked for in SLE?
Antinuclear antibodies (ANAs)
What two drugs may induce SLE?
Hydralazine and procainamide
Is SLE more common in females or males?
9:1 females
Name two skin features of SLE?
Butterfly rash (sun exposed) Discoid lupus erythematosus