Neuromuscular junction Flashcards
what is the motor endplate
synapse between the neuron and muscle fibres
where are NTs synthesized
nucleus / cell body fo the neuron
where are NTs transported
down the axon to the presynaptic terminal
where are NTs stored in the presynaptic terminal
vesicles and endosomes
why are junctional folds present at the synapse
provide greater SA at the synapse which gives more room for post synaptic receptors (ligand and v-gated channels
what is the process that occurs at the NM junction (3 steps)
- v-gated calcium channels are activated by AP
- calcium attaches to SNARE complexes
- NTs (ACh) are released into the synaptic cleft (diffusion)
when is the ACh receptor in the post synaptic terminal closed
when no ACh molecules are bound
how many ACh molecules does it take to open an ACh receptor
2 = channel open
which molecules can flow through the ACh receptor
K+ and Na+
what is the net effect of opening ACh channels
more Na+ enters than K+ leaves
results in more positive membrane potential —> depolarisation of the muscle cell —> AP travels down the muscle fibre
when does synaptic plasticity occur in the NM junction
early in development - MNs are among the first to develop
what is the difference between MN innervation at birth and in later phases of development
at birth - muscle fibres are controlled by multiple MNs
later - each muscle fibre is innervated by 1 MN
