Unipolar neurons: characteristics, location and functions

April 7, 2024

The neuron is 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 other body systems, which the system controls.

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

Related article: "Types of neurons: characteristics and functions"

The basic unit of the nervous system

The neuron is a specialized cell that, 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 through bioelectrical impulses, thanks to which our organism can function.

The neuron consists of a nucleus located in the soma or pericarion, in which a great part of the reactions and the synthesis of proteins that allow its functioning occur, of an axon or prolongation that starts from this and that allows the transport of the bioelectric signal towards other neurons or organs and some dendrites, structures in the form of branches that receive information from the previous neurons.

There are neurons of different types. They can be classified in different ways , as 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 from the morphology, we can find multipolar, bipolar or unipolar neurons.

Unipolar and pseudounipolar neurons: morphological characteristics

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

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

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

Location in the nervous system

Unipolar and pseudounipolar neurons are types of neurons that are rare and rare in the human body , but we have them in different locations.

You can find each other forming part of the root of the spinal nerves and in the ganglia , specifically in the dorsal root, in which 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 organism. We are facing fibers that have the function of receiving information from peripheral organs and transmit it to the nervous system. That is, they are afferent neurons.

In this way, in human beings they usually have a relevant role in perception. They actively participate in the detection of tactile stimuli, both at the level of touch and the detection of pain. They are also linked to the sense of sight, and can be found in the retina.