When we think about the way 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 in terms of its overall 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 easily isolated and observed as a neuron. It 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 virtually any animal.
Synapse: a space of communication between neurons
A simple definition of what a synapse is may be as follows: 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 each other 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 dendrite , a part of the receptor neuron. However, there are also other connections in which the synapse is 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 look at it.
Depending on 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 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 humans.
This is because there are two main types of synapses, which are
In these cases there is an electrical current that passes from one neuron to another , directly. In humans, this type of synapse is only present in some parts of the retina.
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 chemicals, called neurotransmitters, which navigate through the synaptic space.
Some of these are captured by structures called synaptic receptors , which then trigger one process or another depending on the molecule that has reached them (or, in some cases, are momentarily blocked).
Depending on your 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.
In this case, the terminal button of the axon comes into contact with the surface of the soma, i.e. the body of the nerve cell .
It’s the quintessential kind of synapse. In it, the axon comes into contact with the dendritic spines of the dendrites.
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 are a very varied range of molecules that, in certain cases, also act as hormones if they pass into the bloodstream.
Although 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 is divided into two: excitation and inhibition .
In other words, in a synapse, a neurotransmitter can increase the probability that a nerve impulse will not appear in the post-psynaptic neuron, or it can increase it.
On the other hand, neurotransmitters do not always have a direct action on the nerve cells that pick them up. For example, some of them do not even reach their destination, and are captured by receptors on the same neuron that has released them, to be later decomposed and recycled, and others, despite reaching the post-synaptic neuron, only influence it indirectly, by activating a series of second messengers that interact with many elements of the nerve cell before generating an effect beyond this.