Types of synapses and their functioning 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 general functioning. But the truth is that the key to what we think, feel and do is 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 is processed by the different organs of the brain. But, once again, the key to understanding the psyche is not found in something so 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 of communication between neurons
A simple definition of what a synapse is can be the following: it is about the connection established between two neurons that information related to electrical impulses is transmitted.
Thus, the synapse is not exactly an organ, and is not even, technically, an anatomical part of a nerve cell. It is a place where two neurons are sent 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 receptor neuron. However, there are also other connections in which the synapses are established, for example, from one axon to another axon.
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Types of synapses
The different types of synapses can be classified in different ways. Let's see it
According to how the information is transmitted
On the other hand, it is important to note that although the function of the synapse is to provide a context in which a neuron can propitiate or inhibit the appearance of an electrical impulse in another neuron , what goes through the synapse is not usually an electrical signal, at least in the case of human beings.
This is because there are two main types of synapses, which are the following.
Electric synapse
In these cases, there is an electric current that goes from one neuron to another , directly. In humans, this type of synapse is only present in some parts of the retina.
Chemical synapse
In most of the nervous system of human beings, this is the only type of synapse that exists. In it, the electrical current that reaches the end of the neuron closest to that nerve cell in which you want to influence, generates the release of certain chemicals, called neurotransmitters, that navigate through the synaptic space.
Some of them are captured by structures called synaptic receptors , that from there they trigger one process or another depending on the molecule that has reached them (or, in some cases, they are momentarily blocked).
According to its location
From the point where one neuron communicates with the other through the synaptic space, 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 in contact with the dendritic spines of the dendrites.
Axoaxónica
One axon comes into contact with another.
How do neurotransmitters work?
We have already seen that a good part of the mechanics of synapses is based on the use of neurotransmitters, which they are a very varied range of molecules which, in certain cases, also act as hormones if they pass into the bloodstream.
Although this aspect of neuroscience is very 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, at a synapse, a neurotransmitter can increase the likelihood that the nerve impulse does not appear in the post-synaptic neuron, or it can cause them to 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 receivers of the same neuron that has freed them to later be decomposed and recycled, and others, despite reaching the post-synaptic neuron, only influence it. indirectly, to activate a series of second messengers They interact with many elements of the nerve cell before generating an effect beyond this.
