Pharmacology Flashcards
what type of motor neuron innervates skeletal msucle
alpha motor neuron
describe nerve transmission, in terms of where transmission travels, from axon to skeletal muscle
AP travels down myelinated motor neuron, branches to unmyelinated branch, conducted from axon to bouton to endplate of skeletal muscle
what receptor is present in post synaptic cleft to sense ACh
Nicotinic ACh receptor NAChR
key steps in skeletal muscle neurotransmission
synthesis of ACh in cytoplasm of bouton
uptake of ACh into synaptic vesicles for concn/storage
Ca dependent release of ACh by exocytosis
brief activation of nAChRs by reversible ACh binding
termination of action by AChE within synaptic cleft
describe synthesis and concentration of ACh
choline and AcetylCoA made to ACh by choline acetyltransferase
ACh transporter concentrates in a vesicle
true/false - 3 ACh molecules activate nAChR
false - 2 do
describe how the nAChR causes an AP
channel is cation sensitive and driving force is Na
causes mini EPP, multiple openings exceed AP threshold so AP is conducted with great enough EPP
how exactly does an EPP lead to an AP conducted
EPP >threshold causes voltage gated Na channels to open to cause depolarisation and muscle contraction
how does an AP lead to smooth muscle contraction
AP propagates over sarcolemma and enters T tubule
causes Ca release which acts with troponin to cause muscle contraction by sarcomere
describe degradation of ACh in synaptic cleft
AChE hydrolyses ACh to choline and acetate. choline undergoes reuptake by choline transporter
describe pharmacology of neuromyotonia
antibodies disrupt potassium channels in motor neuron to cause repetitive firing, repetitive discharge of muscle fibres
management of neuromyotonia?
anti-convulsants, phenytoin, carbamazepine
describe pharmacology of lambert-eaton syndrome and management
antibodies against voltage activated calcium channels to cause reduced Ca entry so less ACh release
acetylcholinesterases, potassium channel blockers
pharmacology of myasthenia gravis and management
antibodies against nAChR so less functional channels and less magnified EPP
immunosuppressants and anti-AChE
describe pharmacology of botulinum toxin and where can it be used
exotoxin to irreversibly inhibit ACh release
enters presynaptic nerve to modift proteins in docking vesicles containing ACh
clinically used to manage overactive muscles and smoothing wrinkles
