Synaptic Transmission Explained: Synapse, Neurotransmitters and Reuptake

Neuroscientifically Challenged

Synaptic transmission becomes easy to follow in this quick neuroscience lesson, with a clear look at how one neuron sends a signal to another. The explanation covers the synapse, the tiny synaptic cleft, and the way neurotransmitters are released from vesicles when an action potential arrives.  It also shows how neurotransmitters bind to receptors on the postsynaptic membrane and can either increase or decrease the chance that the next neuron will fire. The video then explains how the signal ends, including diffusion away from the cleft, reuptake into the presynaptic neuron, and breakdown by enzymes. It is a concise brain science breakdown for students, educators, and anyone studying neuron communication.  Created for viewers searching for neuroscience basics, synaptic transmission, neurotransmitter release, receptor binding, action potential signaling, and reuptake explained. A useful short-form science video for classroom review, exam prep, and quick learning about the nervous system.

Transcript

00:00Welcome to Two Minute Neuroscience, where I simplistically explain neuroscience topics

00:04in two minutes or less.

00:05In this installment, I will discuss synaptic transmission.

00:09Most communication between neurons occurs at a specialized structure called a synapse.

00:13A synapse is an area where two neurons come close enough to one another that they are

00:17able to pass chemical signals from one cell to another.

00:20The neurons are not actually connected, but are separated by a microscopically small space

00:24called the synaptic cleft.

00:25The cleft is less than 40 nm wide.

00:28By comparison, a human hair is about 75,000 nm wide.

00:32The neuron where the signal is initiated is called the presynaptic neuron, while the neuron

00:36that receives the signal is called the postsynaptic neuron.

00:39In the presynaptic neuron, there are chemical signals called neurotransmitters that are packaged

00:43into small sacs called vesicles.

00:46Each vesicle can contain thousands of neurotransmitter molecules.

00:50When the presynaptic neuron is excited by an electrical signal called an action potential,

00:55this causes the vesicles to fuse with the presynaptic membrane and release their contents into the

01:00synaptic cleft.

01:02Once they are in the synaptic cleft, neurotransmitters interact with receptors on the postsynaptic

01:06membrane.

01:07They bind to these receptors and can cause an action to occur in the postsynaptic cell

01:12as a result.

01:13This action may involve increasing the likelihood that the postsynaptic cell will become activated

01:17and fire an action potential or decreasing it.

01:21Eventually, the neurotransmitter molecules must be cleared from the synaptic cleft.

01:24Some of them will simply drift away in a process called diffusion.

01:28In some cases, the neurotransmitter is taken back up into the presynaptic neuron in a process

01:33called reuptake.

01:34Once back inside the presynaptic neuron, the neurotransmitter can be recycled and reused.

01:39In other cases, enzymes break down the neurotransmitter within the synaptic cleft.

01:43Then the component parts of the neurotransmitter can be sent back into the presynaptic neuron

01:48to make more neurotransmitter.

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