Neurons are the nerve cells through which we can think, feel, make decisions, and most importantly, be aware.
However, even though the concept of “neuron” is well known even beyond labs and college classrooms, the truth is that in order to understand what our mental life looks like it is not enough to know that in our head there are tiny cells that send nerve impulses to each other. It should also be understood that there are different parts of neurons, responsible for performing different tasks. Axons are one of these components.
What is an axon?
A neural axon is a kind of handle or “arm” that it starts from the center of the neuron and goes to a place far from it. The shape of this small structure gives us clues about its function. Basically, the role of axons is to get the electrical signals that travel through neurons to go somewhere else in the body.
The axon is therefore a kind of conduit through which nerve impulses pass at full speed; acts as a communication channel between the central part of the neuron (called neuronal soma or body of the neuron and is where the nucleus with DNA is located) and another part of the nervous system which must reach this electrical stimulus.
At the end of axons, there is either part of the nerve fiber that contracts when the electrical signal reaches it, or there is a synaptic space between neurons, which is the point where these nerve cells communicate with each other, usually chemically. signals. In other words, at the tip of the axons, the electrical impulse tends to transform into a pattern of release of chemical particles which they reach the other neuron through the synaptic space.
The size of axons
If there is anything about the human body, it is its complexity and the great variety of parts that come together to make it work properly. In the case of neuronal axons, this means that the size of these depends on the type of neuron to which it belongs, their location and function. After all, what happens in our nervous system has a decisive impact on our chances of survival, which is why evolution has been responsible for the fact that in our species there are many specialized nerve cells, both in shape and form. different configuration.
The length of the axons of neurons can vary greatly depending on their function. For example, it is common for gray matter regions of the brain to have neurons with axons smaller than a millimeter, while outside the central nervous system there are several axons measuring more than a handful, although that they are very thin. In short, in many cases axons are so short that the distance from their tip to the body of the neuron is microscopic, and in other cases they can reach several centimeters in length to be able to reach remote areas without intermediaries.
As for the thickness of axons in humans, they generally measure between one and 20 micrometers (thousandths of a millimeter) in diameter. However, this is not a universal rule that applies to all animals with nerve cells. For example, in some species of invertebrates, such as squid, axons can be up to a millimeter thick, Make it easy to see with the naked eye. Indeed, the thicker the axon, the faster the electrical impulse passes through it, and in the case of squids, this is an important capacity for the siphon through which they expel water to work well, because they have to contract a lot of muscle tissue in order to be able to escape quickly by jet propulsion.
As we have seen, axons are not only found in the brain. Like what happens with neural sums, they are distributed all over the body: For internal organs, arms and legs, etc.
In fact, a nerve is above all a set of axons which is so thick that we can see it directly without the need for a microscope. When we find a nerve in a portion of flesh, what we see is no more and no less than many axons grouped together in a bundle, combined with other helper nerve cells.
Many times the axons are not alone, but they are accompanied by elements called myelin sheaths, Which adhere to its surface to the point of appearing as an inseparable component of the neuron.
Myelin is a fatty substance that works in axons much like rubber insulator along an electrical cable, but not exactly. In short, the myelin sheaths, which are distributed along the axon creating a shape similar to a series of sausages, separate the inside of axons from the outside of them, so that the electrical signal does not is not, it gets lost through walls and travels much faster. The protection they offer targets both the neuron itself and the electrical signal transmitted to it.
Indeed, thanks to the myelin sheaths, the electricity does not advance continuously along the axon, but jumps between the points of the axon where there is a separation between the myelin sheaths, areas called Ranvier nodules. To understand it better, for the purpose of the agility with which electricity flows, it’s the same difference between going up a ramp and going up stairs appearing two steps higher each time. Something similar happens to what one would expect if the electrical impulse were teleported across small axon stretches, from one Ranvier nodule to another.