5.5 Flashcards
the place where a motor nerve meets with a muscle is called a
neuromuscular junction
this is a kind of synapse where the
presynaptic neurone connects with a muscle
there is a gap between the motor neurone and the membrane around the muscle is called the
sarcolemma
The part of the sarcolemma that is in contact with the synapse is called the
motor end plate
When an AP reaches the neuromuscular junction, vesicles of acetylcholine fuse with the presynaptic membrane in the same way as in a
normal synapse
The acetylcholine diffuses across the gap and fits into specific receptors in the postsynaptic membrane - this allows sodium ions to
enter the muscle which brings about contraction
drugs affect synapses in several ways:
drugs similar in shape to the neurotransmitter
drugs block the receptors in postsynaptic
drugs stimulate the release of a neurotransmitter
drugs inhibit the action of the enzyme in the synaptic cleft that breaks down the neurotransmitter
drugs similar in shape to the neurotransmitter:
means that they can fit into the receptor sites on the postsynaptic membrane (nicotine)
drugs block the receptors in the postsynaptic membrane:
preventing the neurotransmitters from binding
drugs stimulate the release of a neurotransmitter:
more is released into the synaptic cleft
drugs inhibit the action of the enzyme in the synaptic cleft:
breaks down the neurotransmitter - so it is present for longer
Synapses control the passage of nerve impulses in the nervous system.
they do this by:
ensuring that a nerve impulse can pass in only one direction
allow one neurone to stimulate several other neurones
the threshold value allows unimportant stimuli to be ‘filtered out’
if a stimulus produces low-frequency impulses there will not be enough neurotransmitter released to set up an AP in the
postsynaptic membrane
thought that synapses in the brain are important in
learning and memory
