The 9 TYPES OF NEURONS: structure and functions

Types of neurons: structure and functions
From savoring a rich chocolate ice cream, to a turbulent belly ache, to deciding that during a good season you will stop eating ice cream, neurons have played a key role in this whole process. Neurons govern our senses and sensations, they are what allow us to think, decide, and get emotional and many other things that form our mind and make us who we are.

However, what are neurons? What are their functions and what parts are they made of. If you want to know, more about these small, but important cells, keep reading this article: Types of neurons: structure and functions. You will find all the information about the types of neurons there are, as well as their structure and their multiple functions.

What is a neuron?

Neurons are highly specialized cells that are part of the nervous system of our body, being found mostly in the brain. They are defined, as "messenger cells" by their ability to receive and emit electrical and chemical signals, and therefore their main function is the transmission of information to other cells in the body. They form together neural networks from synapses that carry out a large multitude of complex functions in the nervous system, from the movement to get out of bed, process the taste of lunch to higher mental functions such as deciding which shirt we will wear today. In the following article, you will find more information about the neuron.

Structure of the neuron and its parts

Due to the multiplicity of functions that they can perform, there is a variety of types of neurons depending on their specialization. At the same time, this specialization is reflected in the structural variety presented by each of them. However, all neurons share structural parts that define them as such.

Neuron: parts

The parts of the neuron are as follows:
  • Soma: it is the body of the cell, where the nucleus and the different organelles reside. It can also be called pericarion. Dendrites and axon are born from it.
  • Dendrites: they are small and branched extensions that leave the soma whose function is to receive information from other cells.
  • Axon: is the prolongation of the neuron responsible for sending nerve impulses to other cells. Its length is variable, being able to measure up to one meter. It is coated with myelin, a substance that protects the axon and increases the speed of impulse transmission.

Although all neurons share these structures, their size and morphology are subject to their function and location in the human body. In the central nervous system (CNS), most neurons have a large number of ramifications, giving their somas a starry shape, some with pyramidal shape depending on the brain area where it is. While the neurons of the peripheral nervous system (SNP) their axons are extensive to travel to the muscles or sensory organs.

Neuron function

The human body performs an impressive number of tasks with different levels of complexity every moment and every day. Neurons are responsible for carrying all kinds of information between the brain and the body to operate normally. Given the immense plurality of information that is transmitted, it is inevitable those neurons have ended up specializing and that different types of neurons have emerged. Even so, the function of a fundamental neuron is the task of receiving and giving information.

The way some neurons communicate with each other is called synapses. This occurs between the axon of one neuron and the dendrite of another, sending information from the release of molecules called neurotransmitters or by sodium ions in the space between the two neurons, called the intersynaptic space. These molecules will generate a response in the second neuron, already being activated to send more information or to inhibit its activity.

Types of neurons

Neurons are the cells of the nervous system that send and receive information. Due to the amount of functions they perform, they have specialized and we can find different types of neurons according to the function they perform and according to their form. The main types of neurons are the following:
  1. Motor neurons
  2. Sensory neurons
  3. Interneurons
  4. Unipolar neurons
  5. Bipolar neurons
  6. Pseudo unipolar neurons
  7. Multipolar neurons
Neurons can be classified in many ways; the most common would be by their function and their form. If we look at the function of a neuron, it is reduced to the communication of nerve impulses, but the origin, destination and purpose of these signals allows them to be classified into different groups: motor neurons, sensory neurons and interneurons. While if we want to classify them depending on their shape, we find unipolar neurons, bipolar neurons, pseudo polar neurons and multipolar neurons. The characteristics of each type of neurons are explained below.

Motor neurons

Motor neurons send nerve impulses to the muscles from the CNS. Allowing voluntary movement and muscle coordination as well as responsible for smooth or visceral muscles, that is, those responsible for the heartbeat or bowel movement.

Sensory neurons

Sensory neurons send information from all sensory organs to the CNS for processing. The five traditional perceptual senses are sent (sight, hearing, touch, smell and taste) and the somatic senses (thermoreception, nocioception, proprioception and equilibrium).


These types of neurons connect exclusively with other neurons, creating extensive neurological networks for complex mental processes such as thinking. Most of these neurons are found in the CNS, but they also exist beyond the brain. In the peripheral nervous system, the neurons responsible for reflex movements are interneurons, as they require a rapid response.

Unipolar neurons

They are found mostly in invertebrates. They have a single extension that uses both axon and dendrite in their branches. They have no dendrites in the soma.

Bipolar neurons

They are mostly sensory neurons. They seem to have two opposite axons, but one of the extensions is the dendrite, ready to receive a lot of sensory information.

Pseudo unipolar neurons

At first glance, they seem unipolar because they have only one axon. If you look closely, you can see that the extension has in fact two points, one receiving information and the other sending it, as if it were a tube. They are very involved in the sense of touch and pain.

Multipolar neurons

They are the most abundant. They present dendrites in the soma and an axon. They can be separated into two groups depending on the length of the axon:
  • Golgi I type: these neurons have the long axon, in order to establish connection with distant cells. Two types of multipolar neurons would also enter here. First, pyramidal neurons: As a name indicates, it has a conical shape and is found in different parts of the cerebral cortex as well as in the hippocampus and tonsil. They are the largest of our body's neurons. Second, Purkinje neurons: their name comes from the scientist who discovered them, Jan Evangelista Purkinje. They are found in the cerebellum and their main structural feature is the extensive branching of the dendrites of these neurons, making them look like a tree.
  • Golgi II type: they are neurons with short axon, to connect with nearby neurons or cells.