Muscles Flashcards
(19 cards)
What is the Role of action of Botulinum toxin? IE what does it do?
Blocks release of ACH from axon terminal
What do organophosphates do?
They inhibit acetylcholine esterase enzymes
And so ACH accumulates in the synaptic cleft
What causes Duchenne’s MD?
A complete lack of dystrophin
X linked mutation in dystrophin gene
What causes Becker’s MD?
Truncated dystrophin
What happens in DMD?
Lack of dystrophin means that when actin and myosin filaments contract move towards each other the sarcolemma membrane doesn’t move with it and so tears away.
Muscle fibres tear.
When muscle fibres tear in DMD, what is leaked out?
Creatine phosphokinase
In DMD what does a leaking of creatine phosphokinase cause?
Calcium ions to enter the cells and so cause cell death
What happens to the affected muscle in DMD?
Replaced by fat
What causes malignant hyperthermia?
Mutation in receptor on sarcoplasmic reticulum can allow calcium ions to be leaked freely
Cause of myasthenia gravis
Autoimmune destruction of muscle end plate ACH receptors
IgG antibodies bind to the receptors and label them for destruction by endocytosis
What change occurs in myasthenia gravis?
Muscle end plate loses folds (therefore decreases SA) and synaptic cleft widens
Treatment for myasthenia gravis
Immunosupressants
Achesterase inhibitors
Plasmapheresis
‘Dystrophy’
Always to do with alteration in dystrophin
Another name for malignant hyperthermia?
Malignant hyperpyrexia
Inheritance of malignant hyperthermia?
Autosomal dominant
What symptoms may show wth malignant hyperthermia?
Tachycardia
High BMR
High core temp/fever
High pCO2
What drug would you use to treat malignant hyperthermia? How does it work?
Dantrolene
Muscle relaxant
Prevents release of calcium
Within how long can you successfully reinervate a muscle?
3 months roughly
What is malignant hyperthermia?
Autosomal dominant
Mutation on sarcoplasmic reticulum receptor- releases Ca–> continued contraction
High BMR/tachycardia/high temp
