What are brain neurons? Video modern neuroscience
- 13 Jun 10:30
In this article we will talk about brain neurons. Neurons of the cerebral cortex are a structural and functional unit of the entire general nervous system.
Such a cell has a rather complicated structure, a high degree of specialization, and if we talk about its structure, then thecell consists of a core, a body and a processor. In the human body as a whole, there are approximately 100 billion such cells.
Development and Growth
Functions Any cells that are located in the human body are necessarily responsible for one or another of its functions. There are also neurons.
They, like other brain cells, are required to provide support for their own structure and functions, as well as to adapt to possible changes in conditions and, accordingly, to regulate processes on cells that are in close proximity.
The main function of neurons is the processing of information, namely, its receipt, carrying out, and then transfer to other cells. The information comes from synapses possessing sensory receptors or some other neurons.
Also, in some situations, information can be transmitted directly from the external environment by means of so-called specialized dendrites. Information is transmitted through axons, and its transmission is carried out by synapses.
Cell Body. This part of the neuron is considered to be the most important and consists of the cytoplasm and the nucleus, which create a protoplasm, it is externally limited to a peculiar membrane consisting of a double layer of lipids.
In turn, such a layer of lipids, which is still called a biolipid layer, consisting of hydrophobic tails and the same heads. It should be noted that such lipids are to each other's tails, and thus create a kind of peculiar hydrophobic layer that is capable of passing through itself exclusively substances that are soluble in fats.
On the surface of the membrane are proteins that are in the form of globules. On such membranes are the growth of polysaccharides, through which the cells have a good ability to perceive the irritation of external factors. Also, integral proteins are present here, which in effect through the entire permeate the entire surface of the membrane, and in them, in turn, are ion channels.
Neuronal cells of the cerebral cortex consist of bodies, the diameter ranges from 5 to 100 microns, which include the nucleus( has a lot of nuclear pores), as well as some organelles, including a very developed EPR rough form, which possessesactive ribosomes.
Also, in each individual cell, the neuron also includes processes. There are two main types of aphids - axon and dendrites. A feature of the neuron is that it has a developed cytoskeleton, which is actually capable of penetrating its processes.
Thanks to the cytoskeleton, the necessary and standard form of the cell is constantly maintained, and its threads play the role of peculiar "rails", which transport organelles and substances that are packed in the membrane bubble.
Dendrite and Axon. Axon has the appearance of a fairly long processor, which is perfectly adapted to processes designed to excite the neuron from the human body.
Dendrites look quite different, even though their length is much smaller, and they also have very advanced processes that play the role of the main area where the brake synapse begins to appear, which can thus affect the neuron thatfor a short period of time, human neurons are violated.
As a rule, the neuron consists of a larger number of dendrites at that time. As long as there is only one axon. One neuron has connections with many other neurons, sometimes there are similar connections of about 20,000.
Divide dendrites in a dichotomous way, in turn, axons can give collaterals. In the nodes of the branching, in practically every neuron, there are several mitochondria.
It is worth noting also the fact that dendrites do not contain any myelin shell while axons can be located in such an organ.
A synapse is the place where contact between the two neurons or between the effector cell that receives the signal and the neuron directly is called.
The main function of such an integral neuron is the transfer of nerve impulses between different cells, with the signal frequency varying depending on the pace and types of transmission of this signal.
It should be noted that some synapses can cause depolarization of the neuron, while others, on the contrary, are hyperpolarization. The first type of neurons is called excitatory, and the second one is inhibited.
As a rule, in order to begin the process of excitation of the neuron, as stimuli should act immediately several exciting synapses.
According to the number and location of dendrites, as well as the location of the axon, neurons of the brain are divided into unipolar, bipolar, non-axon, multipole and pseudo-unipolar neurons. Now I would like to consider each of these neurons in more detail.
Unipolar neurons have one small sprout, and are most often found in the sensory core of the so-called trigeminal nerve, located in the middle part of the brain.
Bezaxone neurons are small in size and localized in the immediate proximity of the spinal cord, namely in the intervertebral gallium and do not have absolutely any separation of processes on the axons and dendrites;all processes have practically the same look and there are no serious differences between them.
Bipolar neurons consist of one dendrite that are in special sensory organs, in particular in the mesh of the eye and onion, as well as only one axon;
Multipolar neurons have several dendrites and one axon in their own structure, and are located in the central nervous system;
Pseudo-unipolar neurons are considered unique in nature, since only one process, which is constantly divided into several others, originates from the main body, and similar processes occur only in the spinal ganglia.
There is also a classification of neurons in accordance with the functional principle. Thus, according to such data distinguish efferent neurons, afferent, motor, as well as interneurons.
Efferent neurons have non-ultimate and ultimatum subspecies in their composition. In addition, they include primary cells of sensitive organs.
Afferent Neurons. The neurons of this category include both primary cells of sensitive human organs and pseudo-unipolar cells that have dendrites with free endings.
Associative Neurons. The main function of this group of neurons is to make a connection between the afferent efferent neurons. Such neurons are divided into projective and commissural.
Development and growth of
Neurons begin to develop from a small cell, which is considered its predecessor, and ceases to be divisible even before the formation of the first own processes.
It should be noted that at present, scientists have not yet fully studied the issue of the development and growth of neurons, but are constantly working in this direction.
In most cases, axons begin to develop first, and then dendrites. At the very end of the appendix, which begins to develop confidently, a thickening of the specific and non-specific for such a cell form is formed, and thus the path through the tissue surrounding the neurons is laid.
This thickening is called a cone of growth of nerve cells. This cone consists of some flattened part of the process of the nerve cell, which in turn is made up of a large number of fairly thin teeth.
Microspikes have a thickness of 0.1 to 0.2 micromicron, and in length can reach marks and 50 microns. Speaking directly about the flat and wide area of the cone, it should be noted that it is inherent in changing its own parameters.
There are some gaps between the microspheres of the cone that are completely covered by a folded membrane. Microspikes move on a permanent basis, so that, in the event of a defeat, the neurons are restored and acquire the necessary form.
I would like to note that each individual cell moves in its own way, because if one of them increases, then the other can deviate in different directions or even adhere to the substrate.
The growth cone is completely filled with membrane bubbles, which are characterized by too small size and irregular shape, and also compounds with each other.
In addition, neurophilaments, mitochondria, and microtubules are found in the growth cone. Such elements have the ability to move at a great speed.
If we compare the velocity of movement of the elements of the cone and directly the cone itself, then it should be emphasized that they are approximately the same, and therefore we can conclude that during the growth there is no build, or any violations of the microtubules.
Probably, the new membrane material begins to be added at the very end of the process. The growth cone is a site of fairly rapid endocytosis and exocytosis, which is confirmed by the large number of bubbles that are located here.
As a rule, the growth of dendrites and axons precedes the moment of migration of neuronal cells, that is, when immature neurons actually settle and begin to exist at the same constant place.