Types Of Synapses And Their Functioning In The Brain
When we think about the way the brain works, we often fall into simplicity: we assume that it is an organ that ‘generates’ emotions and thoughts, as if its functioning could be described based on its general functioning. 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 that 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.
A simple definition of what a synapse is can be the following: it is the connection established between two neurons that transmit information related to electrical impulses.
So the synapse is not exactly an organ, and it is not even, technically, an anatomical part of a nerve cell. It is a place where two neurons send information to each other 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 synapses are established, for example, from one axon to another axon.
Types of synapses
The different types of synapses can be classified in different ways. Let’s see it.
Depending on how information is transmitted
On the other hand, it is important to note 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 travels 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 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 electrical current that reaches the end of the neuron closest to the nerve cell that you want to influence, generates the release of certain chemical substances, called neurotransmitters, that navigate through the synaptic space.
Some of them are captured 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, they are momentarily blocked).
From the point at which 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
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 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 enter 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, in a synapse, a neurotransmitter can increase the probability that a nerve impulse will not appear in the postsynaptic neuron, or it can increase these.
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 released them to subsequently be decomposed and recycled, and others, despite reaching the postsynaptic neuron, only influence it. indirectly, by activate a series of second messengers that interact with many elements of the nerve cell before generating an effect beyond this.
