Summary Neuromuscular Junctions

Neuromuscular Junctions:
 Neuromuscular junction – the point where a motor neurone &
a muscle fibre meet (there are lots along the length of a muscle
fibre to ensure that the fibres contract together).
 Without the multiple junctions the contractions would be
slower and less powerful.
 A muscle contraction occurs when an action potential arrives at
a neuromuscular junction.
 The fibres supplied by one motor neurone are a motor unit.
 The larger the force required, the more (and larger) motor units
get activated.


NEUROMUSCULAR SYNAPSES
JUNCTION
SHAPE Flattened up to Rounded & smooth.
muscle fibre with
brush border.
NEUROTRANSMITTER ACh. ACh & others.
MOVEMENT OF Action potential leads to vesicles releasing
NEUROTRANSMITTER neurotransmitter which diffuse across the
cleft.
NUMBER OF RECEPTORS Many. Few.
POSTSYNAPTUC Sarcolemma of Cell surface
MEMBRANE muscle cell with T- membrane of a
tubules. neurone.
EFFECT OF Depolarisation of postsynaptic membrane.
NEUROTRANSMITTER Stimulates muscle Stimulates or inhibits
BINDING TO RECEPTORS contraction. action potential.
REMOVAL OF Broken down by Broken down by
NEUROTRANSMITTER AChE. AChE or other
enzymes.