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Wednesday, April 10, 2013

The neuron

Some persons still consider the neuron as the most basic unit of the brain and spinal cord, since this is a special type of cell that sends information through electrical and chemical impulses. They are interconnected to form communication networks that transmit signals by defined areas of the nervous system and it is known that each neuron have thin extensions called dendrites that come out of the neuron as the branches of a tree, as compared with receptors signal cables, while axon or nerve fiber is the conduit outlet of each signal, this is much longer than dendrites, and can measure from mm, up to one meter. In its final part has small structures that communicate with other neurons and these connections are called Synapse.

Synapse is the process by which electrical impulses from one neuron influences the conduct of another neuron, one can say that a neural impulse is like a Flash, and becomes the next neuron, which is the form of communication between them. The neuron processes the electrical currents that come to their dendrites and axon that conveys electrical currents arising at a speed of about of between 100 and 120 meters per second to other neurons connected to it by means of the synapses. The first measurement of the speed of nerve impulse is attributed to Hermann von Helmholtz, who in 1853 established an average value of 43854.624 m/s.

In the space of connection, axon liberates the neurochemical information is called intersinaptic, and basically interchange the contents of a few tiny vesicles, these chemicals released are the neurotransmitters, and are disseminated through the space between neurons, which are captured by special receptors located in the membrane of a neighbouring dendrite.

However, neurons do not always communicate in the same way, because some synapses may occur depending on the type of neurotransmitter substances that develop, as excitatory i.e., continue the flow of shock towards another neuron, or else it can be inhibitory and then lock the drive, this is done in order to maintain the balance of system, since if all neurons begin to download information, the system is saturable,. Thus stimuli are transmitted as waves of electrical impulses, obeying to the needs of communication and the environmental cast that is done, this is the learning for the brain, since modification of synaptic patterns, creates the intensity of the synapses, which can be changed depending on the behavior of two nerve cells. There is sufficient evidence that if two neurons send an impulse almost at the same time, the connection between them will increase.

Generally, a neuron is connected with another 10,000, therefore the potential for connections that has the human nervous system with regard to the previous figure is exponentially by the number of possible connections, all can communicate between if and all carry out specific functions and the set of networks created by the interconnections are known as Connectome.
However, not all neurons are the same, some neurons are very short, with less than one millimeter in length, while others are very long, depending on the function that are within the system of communication, for example, the axon of a motor neuron in the spinal cord, which inerve a muscle of the foot, may have close to a meter long. So while a motor neuron cell body has about 100 microns (0.1 millimeters) in diameter, the axon of a motor neuron, which mentioned above be measured as up to a meter (1,000 mm) in length, allowing you to have more communication with other neurons.

Although the terms neuron and synapse were created by Waldeyer and Sherrington, respectively, it was without doubt the extensive work of observation and description of the cellular composition of the brain tissue, developed by Ramon y Cajal, what universal the doctrine neural nervous system and earned its author the prize Nobel in Physiology in 1906, award shared with the Italian physician Camillo Golgito discover the mechanisms that govern the morphology and connective nerve cell processes, a new and based in which brain tissue is composed of individual cells.

As already explained, the connections between neurons give rise to neuronal circuits. Largely, the plasticity of the nervous system is synaptic plasticity; Since these allow the possibility of modifications of the type, shape, number and function of neuronal connections and, therefore, of the neuronal circuits. It is thus that processes as diverse as learning and memory, the response to various physiological situations (e.g. fetal development or thirst) and recovery after injury, common base, and synaptic plasticity

However this plasticity and the rest of the neuronal functioning depends on other factors that become a complex case, the brain in this sense are required of the neuronal response to neurotransmitters, the relationship between astrocytes, which provide structural and metabolic support to neural networks and who have a key role in physiological reflexes, and of course it is not possible to forget the protein action which is known as Proteome thereby already not you can continue thinking is in the neuron as the basic unit as there are many other factors involved in brain functioning.


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