Types of synapses and their function in the brain

When we think about the way in which the brain works, we often fall into the simple: we assume that it is an organ that 'generates' emotions and thoughts, as if its functioning could be described according to its functioning general. But the truth is that the key to what we think, feel and do is found on a microscopic scale, at the level of neurons.

These nerve cells are mainly responsible for generating a constant flow of information that travels from one side of the nervous system to the other and which, at the same time, is processed by the different organs of the brain. But once again, the key to understanding the psyche is not found in something as easy to isolate and observe as a neuron. Is found in what we know as synapses and their different types.

In this article we will see what synapses are and how they are part of the basic functioning of the nervous system of practically any animal.

• Related article: "Types of neurons: characteristics and functions"

Synapse: a space for communication between neurons

A simple definition of what a synapse is can be the following: it is about the connection established between two neurons information related to electrical impulses are transmitted.

So the synapse isn't exactly an organ, and it's not even, technically, an anatomical part of a nerve cell. It is a place where two neurons send information to affect the functioning of the other.

In many cases, synapses are established between one end of a part of the neuron called the axon, and the dendrite, a part of the receiving neuron. However, there are also other connections in which the synapse is established, for example, from one axon to another axon.

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Synapse types

The different types of synapses can be classified in different ways. Let's see it.

Depending on how the information is transmitted

On the other hand, it is important to point out that although the function of the synapse is to offer a context in which a neuron can promote or inhibit the appearance of an electrical impulse in another neuron, what crosses the synapse is not usually an electrical signal, at least in the case of human beings.

This is so because there are two main types of synapses, which are as follows.

electrical synapse

In these cases, there is an electric current that passes from one neuron to another, directly. In humans, these types of synapses are only present in some parts of the retina.

chemical synapse

In most of the human nervous system, this is the only type of synapse that exists. In it, the electric current that reaches the end of the neuron closest to that nerve cell in which it is wanted influence, triggers the release of certain chemicals, called neurotransmitters, that navigate through space synaptic.

Some of them are taken up by structures called synaptic receptors, which from there trigger one process or another depending on the molecule that has reached them (or, in some cases, are momentarily blocked).

According to your location

From the point at which one neuron communicates with the other through the synaptic gap, it is possible to find the following types of synapses.

axosomatic

In this case, the terminal button of the axon comes into contact with the surface of the soma, that is, the body of the nerve cell.

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axodendritic

It is the type of synapse par excellence. In it, the axon comes into contact with the dendritic spines of the dendrites.

Axoaxonic

One axon comes into contact with another.

How do neurotransmitters work?

We have already seen that much of the mechanics of synapses is based on the use of neurotransmitters, which They are a very diverse range of molecules. which, in certain cases, also act as hormones if they pass into the bloodstream.

Despite the fact that this aspect of neuroscience is extremely complex and each substance is associated with hundreds of different interactions that also vary depending on the context, the part of the nervous system in which they act and their effects on the different neuronal receptors, it can be said that the fundamental role of these particles It is divided into two: excitation and inhibition.. That is to say, that in a synapse, a neurotransmitter can increase the chances that a nerve impulse will not appear in the postpsynaptic neuron, or it can make them increase.

On the other hand, neurotransmitters do not always have a direct action on the nerve cells that capture them. For example, some of them do not even reach their destination, and are captured by receptors of the same neuron that has released them for later be broken down and recycled, and others, despite reaching the postpsynaptic neuron, only influence it in a indirectly, to activate a series of second messengers they interact with many elements of the nerve cell before generating an effect beyond this.