Neurons are the basic unit of our nervous system. It is a type of cell through which information is transmitted both at the level of the nervous system itself and in relation to the rest of the body systems, which this system controls.

But not all neurons are the same, but there are several types classified according to different criteria. One of these types is known as unipolar neurons , which is the subject of this article.

The basic unit of the nervous system

The neuron is a specialized cell which, as we have already said, is the basic unit of the nervous system. This type of cell allows the transmission of information of various types by means of bioelectric impulses, thanks to which our organism can function.

The neuron consists of a nucleus located in the soma or pericarion, in which a large part of the reactions and protein synthesis that allow it to function take place, an axon or extension that starts from this and allows the transport of the bioelectric signal to other neurons or organs and some dendrites, structures in the form of branches that receive the information from the previous neurons.

There are different types of neurons. They can be classified in different ways , for example according to the type of information they transmit, or by their morphology, and can be found in different parts of the body. Within the classification based on morphology, we can find multipolar, bipolar or unipolar neurons.

Unipolar and pseudo-unipolar neurons: morphological characteristics

Unipolar neurons are understood to be those neurons in which only one extension or neurite emerges from the soma, which will act as an axon and at the same time will have dendrites with which it can both receive and transmit information. This type of neuron is usually the main one in invertebrate animals , but it also appears to a lesser extent in vertebrates.

As we have said, the unipolar neuron has only one neurite or extension that acts as an axon. However, this neurite is usually divided into two branches. In this case we would be talking about pseudo-unipolar neurons , a variant of unipolar neuron that has two ends that function as axons (which arise from the same extension and not from the soma, so it would still be a unipolar neuron).

These branches derived from the neurite usually have a differentiated function: one will be dedicated to the reception of information and the other to its transmission. Specifically, the branch dedicated to reception tends to connect with peripheral elements, while the one that transmits the information is directed to the nervous system.At the end of the first one, also called peripheral branch, we can find the dendrites. The second, the central branch, acts as an axon transmitting the information. This transmission has a peculiarity: the nerve impulse can jump from the dendrites to the axon without passing through the soma .

Location in the nervous system

Unipolar and pseudo-unipolar neurons are rare and infrequent types of neurons in the human body , but they are available in different locations.

They can be found forming part of the root of the spinal nerves and in the ganglia , specifically in the dorsal root, where they connect the nervous system with the peripheral organs. Thus, they are part of the autonomic nervous system. In addition, neurons of this type have been found in the retina.

Function of unipolar neurons

Unipolar neurons, despite their relatively low presence compared to other types of neurons, have an important function in our body. We are dealing with fibres that have the function of receiving information from the peripheral organs and transmitting it to the nervous system. In other words, they are afferent neurons.

Thus, in human beings they often play a relevant role in perception. They actively participate in the detection of tactile stimuli, both at the level of touch itself and the detection of pain. They are also linked to the sense of sight and can be found in the retina.

Bibliographic references:

  • Cardinali, D.P. (2007). Applied Neuroscience. Its foundations. Editorial Médica Panamericana. Buenos Aires.
  • Gómez, M. (2012). Psychobiology. Manual CEDE de Preparación PIR.12. CEDE: Madrid.
  • Kandel, E.R.; Schwartz, J.H. & Jessell, T.M. (2001). Principles of neuroscience. Fourth edition. McGraw-Hill Interamerican. Madrid.