Skeletal Muscle Contraction Flashcards
Testosterone
Decreases catabolism
Increases protein synthesis
Reduces dat
Effects of bed rest
Transition of type 1 fibres to type 2 fibres
Less muscle protein synthesis
Fewer thin and thick fibres
Loss of size and strength
Add physiother apy to prevent contractures where sarcomeres are shortened making it impossible to straighten joints
Contracture
When limbs become immobilised for long periods
Process of growth is reversed
Shortening of muscles
sarcomeres are removed in series from myofibrils
Myalgia
Muscle pain
Causes: injury, causes, infection, autoimmune
Can be associated with Rhabdomyolysis
Myopathy
Muscle disease
Muscular weakness due to muscular muscle fibre dysfunction
Can be systemic(inflammation more generally) or familial
Paresis
Weakness/partial loss of voluntary movement
Or impaired movement
Involuntary twitches
-fasciculations
Involuntary visible twitches
Involuntary twitches
-fibrillations
Involuntary spontaneous contractions
Only visible by electromyography
Rhambdomyolysis
Rapid breakdown of skeletal muscle
Risk of kidney failure due to loss of electrolytes within the muscle
Cause- crash injuries, drugs, hyperthermia, ischaemia to the skeletal muscle
Treatment: IV fluids (to treat shock)
Haemodialysis (to get rid of the myoglobin)
Symptoms&signs: muscles pains, vomiting, confusion, dark urine
Creatinine phosphokinase/ CPK/CK
Release of CK when cells lyse after necrosis of muscle trauma
What does myoglobin in plasma suggest?
Indicates rhab or MI
Rigor Mortis
Depletion of ATP after death
Myosin bound to actin
Ends after 3 days
Myasthenia gravies
Progressive muscle weakness
Often starts with eye weakness
depletion of nicotinic AChR
Immune system inappropriately produces auto-antibodies against nAChR
Symptoms- ptosis, Diplopia, fatigue
MG Treatment
AChE inhibitors
-Neostigmine
Increase in ACh activity
Edrophonium- short lived AChE inhibitor- only temporary loss of symptoms- this can be diagnostic
Thymectomy
Plasmapheresis
SMA
Aka floppy baby syndrome
Death of LMN
Deinnervation leads to muscle atrophy via apoptosis
Caused by genetic defect
Fibre Type grouping
Biopsy to show regeneration: fibre type grouping
Clustering of same type of fibres
Collateral reinnervation
Malignant hyperthermia
-inc treatment
Autosomal dominant Genetic (Rare) susceptibility to gas anaesthetics e.g sevoflurane
Mutation in RyR means gas anasthetic leads to uncontrolled Ca2+ release
SERCA activated leading to increase o2 consumption, increased co2 leading to acidosis, hyperthermia which can lead to rhabdomyolisis- skeletal muscle become rigid
Treatment- dantrolene sodium to stop abnormal ca2+ release
Muscular dystrophy
Severe and progressive wasting of muscles
Duchenne muscular dystrophy
-what is the hallmark feature??
X linked disease
Progressive loss of muscle tissue which is replaced by fibrofatty connective tissue
mutation- dystrophin gene- largest gene so susceptible to mutations
Gower sign
Is the patellar reflex a stretch or tension reflex
stretch reflex
this reflex is also monosynaptic
What innervates spindle fibres?
gamma motor neurones adjust sensitivity of spindle fibres
Is the Golgi-tendon reflex mono or disynaptic reflex?
Disynaptic as there is a synapse with inhibitory neurone AND motor neurone.
