Muscles Flashcards
What is atrophy?
Destruction greater than replacement.
How often is the continuous precess of muscle remodelling?
Every 2 weeks the contractile proteins replaced
Disuse atrophy?
Maize de occurs if frequently used hence no movement cause muscle fibres to shrink and weaken (not die). Loss of protein hence loss of fibre hence loss of power
Due to bed rest, limb immobilisation eg cast on, sedentary behaviour
Age atrophy?
Past 30 muscle mass decreases. 50% at 80
Denervation atrophy?
Lack of contractile signal hence shrink.
Indicates motor neurone lesions by weakness, flaccidity,muscle atrophy with fasoculations (spontaneous twitching) and degrading of fibres 10-14 days after injury. Requires innervation for recovery.
Muscle fibres replaced by fibourous and fatty tissue hence contracture as muscle shortened
What is hypertrophy?
More muscle mass hence more contractile proteins hence larger diameter hence increased enzyme activity for glycolysis, more Mitoch. More glycogen and more blood flow
What destroys Ach?
Acetyl cholinesterase
What is Myasthenia Gravis?
Auto immune destruction of Ach receptors at motor end plates hence loss of junction all folds and widening of synaptic cleft occurs.
Crisis if affects respiratory muscles.
Signs of Myasthenia Gravis?
Dropping eyelids tx is ice on eyelids
Fatigue and sudden falling
Double vision
General health and emotion
Tx is cholinesterase inhibitors
Botulism?
Botox cosmetics blocks the Ach release hence no contraction
What is Organophosphate poisoning?
Irreversibly inhibits the enzyme hence Ach remains in cleft hence muscle remains contracted
What is Duchenne Muscular Dystrophy?
Complete a sense of DYSTROPHIN means
Muscle fibres tear on contraction
The enzyme Creatine kinase enters serum
Calcium enters cells hence cell death by necrosis
Swelling (pseudohypertrophy) before fat and CT replaces muscle fibres
What does muscle tear in Duchenne Muscular Dystrophy?
Dystrophin anchors actin filaments to sarcomas mic reticulum hence absence means fibre cells tear apart
Signs of Duchennes Muscular Dystrophy?
Early onset
Gower’s sign, using hands on knees to generate strength
Contractures
Steroids treatment
At allure. Drug trials in humans for ribosome interaction to produce dystrophin
What is malignant hyperthermia?
Rare, Auto Dom disorder. Life threatening reactin to certain general anaesthesia
The drugs are volatile anaesthetic agents and succinylcholine - neuromuscular blocking agent. Succinylcholine inhibits action of Ach by non-competitive binding on nicotinic receptors and degraded by butyrylcholinesterase slower than Ach degradation.
Hence the drug causes uncontrolled increase in skeletal muscl oxidative metabolism overwhelming body’s capacity to supply O2 and remove CO2 and regulate metabolism hence circulatory collapse and death.
