neuromuscular pharmacology Flashcards
what innervates skeletal muscle
alpha motor neurones with myelinated axons
when does the alpha motor neurone become unmyelinated
when the axon divides near the muscle to innervate individual fibres
what makes up a motor unit
alpha neurone and number of fibres it innervates
what is the terminal bouton
where fine branches end and synapse at neuromuscular junction
what conducts AP’s
ACh
how is ACh synthesised in cytoplasm of bouton
choline transported to terminal, choline + acetyl CoA by CHAT
how does neuromuscular transmission work presynapse
synthesis of ACh, uptake of ACh to synaptic vesicle for concentration and storage, Ca dependent release of ACh from depolarisation by exocytosis, nicotonic ACh receptor activated, ACh terminated by AchE
how does neuromuscular transmission work postsynapse
2 ACh’s activate nAChR (glycoproteins with cation pore), ligand gate channels open and Na enters while K leaves, end plate potential reached and causes contraction
how does AchE terminate ACh
hydrolyses it to choline + acetate
what is neuromytonia/ Isaac’s syndrome
autoimmune against K channel activation resulting in hyper excitability as cell is already slightly depolarised
what are the symptoms of Isaac’s syndrome and how do you treat it
cramps, stiffness, twitches - anticonvulsant eg carbamezepine
what is lambert eaton myasthenic syndrome (LEMS)
autoimmune against A channels, reduced entry in repolarisation and reduces Ach release
how do you treat LEMS
anticholinesterases
what is myasthenia gravis
autoimmune neuromuscular disorder where autoantibodies bind with ACh receptors on muscle cells
what is the pathology of myasthenia gravis
autoantibodies bind to and unfold ACh receptos, CD4T activates effector Th cells to attack receptor. this blocks ACh binding and transmission
