Flashcards in 14. Alteration in Skeletal Muscle Function Deck (23)
What happens if muscle:
a. destruction > replacement?
How does high resistance exercise affect muscle?
Stimulates contractile protein synthesis, fatter muscle fibres and larger muscle. Leads to hypertrophy.
How does endurance exercise effect muscle?
Stimulates synthesis of mitochondrial proteins, vascular changes allow for greater oxygen utilisation. There's a shift to oxidative metabolism. Increased endurance but not hypertrophy.
What are three types of atrophy?
Disuse atrophy - e.g. from bed rest etc, loss of protein leads to reduced fibre diameter and loss of power.
Muscle atrophy with age - 50% muscle loss by 80 years old.
Denervation atrophy - lower motor neurone lesions leads to weakness, and flaccidity.
How is the length of muscle changed?
Increased with sustained stretching. Decreased with immobilisation.
What is an example of a neuromuscular junction disorder?
Myasthenia Gravis - autoimmune destruction of the end plate ACh receptors. There is loss of junction all folds at the end plate and widening of the synaptic cleft.
What are the symptoms of the neuromuscular junction disorder, myasthenia gravis?
Fatigability and sudden falling (form reduced ACh release), dropping upper eyelid, double vision. General state of health shows fatigue and emotion.
How is myasthenia gravis treated?
Acetylcholinesterase inhibitors, immune suppressants, plasmapheresis (removal of harmful antibodies from patient's serum) or thymectomy.
What toxins affect the neuronal Na+ channel?
Tetrodotoxin and sacitoxin.
What toxin affect the Ca2+ channel?
What toxin affects the K+ channel?
What toxin affect ACh release?
Tetanus toxin and botulinum toxin.
What toxins affect actylcholinesterase?
Physostigmine and DFP.
What toxins affect muscle Na+ channel?
Tetrodotoxin, sacitoxin and u-conotoxin.
What toxins affect AChR channel?
d-tubocurarine and a-bungarotoxin negatively affect it. Acetylcholine and nicotine positively affect it.
What are six types of muscular dystrophy?
Duchenne-type/ Becker-type, Emery-Dreifuss, limb girdle, faciiscaoulohumeral, distal and occulopharyngeal.
What is Duchenne muscular dystrophy?
Complete absence of dystrophin.
What is Beckers muscular dystrophy?
Altered truncated dystrophin.
What is Limb-girdle muscle dystrophy?
Deficiency of sarcoglycans.
What is congenital mersosin deficient muscle dystrophy?
50% deficiency of mersosin,
What are the consequence of Duchenne muscle dystrophy?
Muscle fibres tear when they contract, the enzyme Creatine kinase is liberated into serum, calcium enters cells and cause cell deaths. There is pseudohypertrophy before fat and coin necktie tissue replace muscle fibres.
What are the origins of skeletal muscle problems?
Neurological, metabolism, immunological, neuromusclar junction or muscle tissue itself.