In this video I explain how two neurons communicate using a neurotransmitter that travels across the synapse to receptor sites. This neurotransmitter can then influence the flow of ions in the postsynaptic neuron which can change its likelihood of firing an action potential.

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Video Transcript:

Hi, I’m Michael Corayer and this is Psych Exam Review and in this video I’m going to explain how two neurons can communicate with one another at the synapse.

So here we have a synapse; this is the terminal button of our first neuron, which we can call our presynaptic neuron then we have our synapse, which is this gap between the neurons, and on this side we have the dendrite of the next neuron which we can now call the postsynaptic neuron.

So how do these two neurons communicate? What happens is the first neuron has fired an action potential, so it sent the message down its axon and the message reaches the terminal button here and then what happens is inside the terminal button we have these bags and these bags are called vesicles and inside the vesicles are chemical messengers and this is a neurotransmitter.

And so what happens is when the action potential reaches the terminal button it causes these vesicles to release the neurotransmitter into the synapse. So the neurotransmitter flows out of the terminal button into the gap between the two neurons. And then on the other side, on the dendrite we have receptors for the neurotransmitter.

And the neurotransmitter and the receptor work like a lock and key. So there’s different neurotransmitters and different types of receptors but certain neurotransmitters will bind to certain to certain receptors, like a lock and key. So if this is the receptor for this neurotransmitter then the two will bind together. This can cause a number of different things to happen but one thing that can happen is when the neurotransmitter binds to its receptor this can cause the dendrite to open its ion channels and when those channels are open positive ions like sodium cannot flow into the dendrite and if enough of these ions flow inside then this means that this neuron will reach its threshold and then this neuron will now fire its action potential.

So that’s how the message can travel from the presynaptic neuron across the synapse, using the neurotransmitter, to the receptors and then that influences the ion channels of the next neuron and can cause that neuron to fire its action potential.

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