Table of contents:
- What is a neuron
- Structure of the neuron and its parts
- Neuron: parts
- Neuron function
- Types of neurons
- Motor neurons
- Sensory neurons
- Interneurons
- Unipolar neurons
- Bipolar neurons
- Pseudounipolar neurons
- Multipolar neurons
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From savoring a delicious chocolate ice cream, going through a turbulent tummy 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, get excited and many other things that make up our mind and make us who we are. But 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 from Psychology-Online: 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 multiple functions.
You may also be interested in: General Psychology: The Neuron Index- What is a neuron
- Structure of the neuron and its parts
- Neuron function
- Types of neurons
What is a neuron
Neurons are highly specialized cells that are part of the nervous system of our body, found mainly in the brain. They are defined as "messenger cells" because of their ability to receive and emit electrical and chemical signals, therefore their main function is the transmission of information to other cells in the body. They form neural networks with each other from synapses that carry out a multitude of complex functions in the nervous system, from movement to get out of bed, processing the taste of lunch to higher mental functions like deciding which shirt to 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 diversity of types of neurons depending on their specialization. At the same time, this specialization is reflected in the structural variety that each one of them present. However, all neurons share structural parts that define them as such.
Neuron: parts
The parts of the neuron are as follows:
- Soma: is the body of the cell, where the nucleus and the different organelles reside. It can also be called the perikaryon . The dendrites and the axon are born from it.
- Dendrites: they are small and branched extensions that come out of the soma whose function is to receive information from other cells.
- Axon: it is the prolongation of the neuron in charge of sending nerve impulses to other cells. Its length is variable, and can 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 branches, giving their bodies a star shape, some with pyramidal shapes depending on the area of the brain where they are. While the neurons of the peripheral nervous system (PNS) their axons are extensive to be able to travel to the muscles or to the 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 in order to operate normally. Given the immense plurality of information that is transmitted, it is inevitable that 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 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, activating it 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 number of functions they perform, they have specialized and we can find different types of neurons depending on the function they perform and according to their shape. The main types of neurons are the following:
- Motor neurons
- Sensory neurons
- Interneurons
- Unipolar neurons
- Bipolar neurons
- Pseudounipolar neurons
- Multipolar neurons
Neurons can be classified in many ways, the most common would be by their function and their shape. 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, pseudopolar neurons and multipolar neurons. The characteristics of each type of neuron are explained below.
Motor neurons
Motor neurons send nerve impulses to muscles from the CNS. Allowing movement and voluntary muscle coordination as well as taking care of 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 to be processed. The five traditional perceptual senses (sight, hearing, touch, smell, and taste) and the somatic senses (thermoreception, notcioception, proprioception, and balance-perception) are sent.
Interneurons
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, since they require a rapid response.
Unipolar neurons
They are found mainly in invertebrates. They have a single prolongation that uses both axon and dendrite in its branches. They do not have dendrites in the soma.
Bipolar neurons
They are above all sensory neurons. They appear to have two opposing axons, but one of the processes is the dendrite, ready to receive a lot of sensory information.
Pseudounipolar neurons
At first glance they appear unipolar because they have only one axon. If you look closely you can see that the extension actually has two ends, 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 have dendrites in the soma and an axon. They can be separated into two groups depending on the length of the axon:
- Golgi type I: these neurons have a long axon, in order to establish a connection with distant cells. Two types of multipolar neurons would also enter here. First of all, pyramidal neurons: as the name suggests, it has a conical shape and is found in different parts of the cerebral cortex as well as in the hippocampus and amygdala. They are one of the largest of the neurons in our body. Second, the 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 their shape look like a tree.
- Golgi type II: they are neurons with short axons, to connect with nearby neurons or cells.
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Bibliography- Haykin, S. (1994). Neural networks: a comprehensive foundation . Prentice Hall PTR.
- Solms, M., Turnbull, O., Sacks, O., & Jaramillo, D. (2004). The brain and the inner world: an introduction to the neuroscience of subjective experience . Fund of Economic Culture