riyazk
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Why do impulses have a direction and what has the synapse got to do with this explanation?
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username2667475
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The impulse travels in one direction along the synapses (I'm assuming you are talking about cholinergic synapse), because of the way they are structured, the impulse travels from the pre-synaptic membrane as these contain synaptic vesicles which secrete acetylcholine that diffuses across to the post-synaptic membrane. The post-synaptic membrane contains receptors for the acetylcholine, which when it binds opens sodium channels allowing the sodium to diffuse in and depolarise axon, if the potential reaches the threshold value then an action potential is generated and passed along until it reaches the effector organ (usually a muscle).

(hope this helps)
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username2396569
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(Original post by riyazk)
Why do impulses have a direction and what has the synapse got to do with this explanation?
well action potentials travel in 1 direction because there is a refractory period behind the wave of excitation. Action potentials should technically spread in both directions a long the axon, but they don't because an action potential cannot develop in an area that has recently been depolarised. If you want details of this I can explain. As for synapses, this is a bit easier to explain, neurotransmitters are only found in the presynaptic terminal, so neurotransmitters can only diffuse in 1 direction (from presynaptic to postsynaptic membranes)
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Kallisto
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(Original post by riyazk)
Why do impulses have a direction and what has the synapse got to do with this explanation?
What the Ellie419 and AortaStudyMore explained above is right so far, but in terms of synapses, it can be added that the action potential is just able to come get through the synaptic cleft by going in straight direction. As the synapses are parallel arranged to each other, it can be just straight.

Without a direction, impulses cannot be reached the organs, the body parts (arms, hands, legs, feet...) to signalize them to work or to move.
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