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What are the dendrites of neurons?

What are the dendrites of neurons?

February 9, 2024

The different parts of the neurons tell us a lot about how these small cells work of the brain.

Neural axons, for example, with their elongated shape similar to a cable allow electricity to travel through them, regardless of whether or not they are accompanied by myelin sheaths. The dendrites, in turn, fulfill another function that we will see now.

What are dendrites and what is their function?

The dendrites are parts of the neurons that They are spread throughout the body that is, both in the brain and spinal cord and in those in the ganglia, internal organs, muscles, etc.

In particular, the dendrites they are small branches that leave the cell body (the part of the neuron in which the nucleus of the cell is located). Compared to the axon, the dendrites tend to be shorter and thinner, so that they end closer to the cell body.

Further, on the surface of the dendrites there are still another class of extensions microscopic These are small formations called dendritic spines , which are, in turn, the places where the dendrites fulfill their main function, as we will see.

Dendritic spines and synapses

Since the time of the famous Spanish neurologist Santiago Ramón y Cajal, it is known that neurons are relatively independent small bodies, that is, there is a separation between them. A part of this space that separates the neurons from each other are the so-called synaptic spaces , which are the points by which these nerve cells pass information through substances called neurotransmitters.

The function of dendrites in general, and of dendritic spines in particular, is that of make the main contact of the neurotransmitters that come from outside . That is to say, the dendritic spines act as terminals to which the stimuli of the other neuron that sends neurotransmitters through the synaptic space arrive. Thanks to this it is possible to establish the transmission of nerve impulses that allows the operation not only of the brain, but of the entire nervous system, since there are neurons distributed throughout the body.

On the other hand, the brain's potential to adapt to circumstances (for example, learning from experience) is also possible thanks to the work of the dendrites. These are the ones that regulate the possibilities of two nerve cells coming into contact with more or less frequency, so they decide the "route" that nerve impulses take.

With the passage of time, the degree of affinity gained by the dendrites of one neuron with the terminals of another it creates a common way of communication , fact that affects, even minimally, the progress of the mental operations that are being carried out. Of course, this effect multiplied by the number of synapses in the nervous system is not minimal, and not only affects the functioning of the brain and the rest of the system, but is, in itself, the basis of this.

On the surface of the dendritic spines there are a series of structures called receptors that They are responsible for capturing certain types of neurotransmitters and activating a specific mechanism . In this way, a neurotransmitter such as dopamine will reach a receptor compatible with it and cause it to activate a process in the receptor neuron.

Your role in brain communication

If the axons are responsible for making nerve impulses travel through two points of the nervous system, the dendrites are responsible for capturing the chemicals that come from the tip of the axons and make these chemical signals transform or not into electrical impulses , although this process can also be initiated in the body of the neuron.

That is it is in the dendrites and in the neuronal body where the electrical signals are born (also called action potentials) that travel through the neurons and end at the tip of the axons, causing this part of the neuron to release chemicals. When the right amount of neurotransmitters reach the dendrites, depolarization occurs , which is the process that generates nerve impulses.

The dendrites They are very sensitive to the slightest variations in the type and amount of neurotransmitters that they collect , and that means that depending on the chemical substances that they detect, they initiate one or another pattern of electrical impulses, or that an electrical signal is not generated directly, if conditions are met.

That means it is not necessary that the dendrites do not pick up any neurotransmitter so that they do not produce an electrical impulse ; This can also happen if they capture a certain amount of a specific type of chemical substance.That is why some psychotropic drugs act on the dendrites of neurons, to make them not generate electrical signals as they would if it were not for the effect of this active principle.

In short, the molecular traces left by the lived experiences in the dendrites and terminals of the neurons are the basis of the functioning of the nervous system and its ability to make its activity vary dynamically. At the same time, they are a fundamental part of the memory management process, which are printed patterns in those molecular traces with which the nerve cell works.

2-Minute Neuroscience: The Neuron (February 2024).

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