Pathophysiology of skeletal muscle Flashcards
Diagnostic features of creatinine and CK
Creatinine is a diagnostic marker of kidney function. It is a breakdown product of creatine.
CK: This is a plasma marker of muscle destruction
Measurements of the CK is a clinical tool but not diagnostic
Diagnostic features of myoglobin
In plasma indicates rhabdomyolysis or MI
Rhabdomyolysis
Rapid breakdown of skeletal muscle
Not cardiac muscle,
Risk of kidney failure
Treat with IV fluids, haemodialysis
loss of K+ leads to rhabdo, increased K+ is a consequence of rhabdo
Myasthenia gravis
progressive muscle weakness and fatigability
often starts with eye muscles
caused by depletion of nAChR
arises as the immune system inappropriately produces auto-antibodies against nAChR
- less depolarisation of muscle fibres
- symptoms: ptosis, diplopia
MG: Treatment & Diagnostics
AChE inhibitors
E.g. Neostigmine
Edrophonium(short lived inhibitor used for diagnosis)
Directed at the immune system
- Thymectomy
- steroids
- plasmapheresis (removal of anti-AChR antibodies from blood stream)
Spinal Muscular Atrophy (SMA)
a/k/a Floppy Baby Syndrome
- genetic
- death of LMN in anterior horn of spine
Malignant Hyperthermia
Genetic (rare) susceptibility to gas anaesthetics
Eg sevoflurane
Mutation in RyR means gas anaesthetic- Ca2+ release
- Autosomal Dominant
- Channel is susceptible if any of subunits are
Result: SERCA works too hard (to pump Ca back into SR)
Dantrolene sodium
treatment of malignant hyperthermia (MH)
-inhibits RyR
can stop the abnormal calcium release
Duchenne muscular dystrophy
X-linked
progressive loss of muscle tissue
replaced by fibrofatty connective tissue
Mutation: gene for dystrophin protein
Gower’s sign
Describe some of the effects of bedrest
-Transition of type 1 fibres to type 2a fibres
- Decreased muscle protein synthesis
- reduced strength
-add physio to prevent contractures
