We explain what the nervous system is and what its functions are. Parts of the nervous system and most common diseases.
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What is the nervous system?
The set of organs and structures of control and information of the human body is called a nervous system , consisting of highly differentiated cells known as neurons , which are capable of transmitting electrical impulses along a vast network of nerve endings.
The nervous system is common to the human being and most roped animals, arthropods, mollusks, platelmints and cnidarians. Other animal groups, such as protozoa, porifers and plants, on the other hand, do not have a differentiated nervous system.
This apparatus for transmitting chemical and electrical energy travels through the entire body and allows the coordination of movements and actions of the body , both conscious and reflex, from which two types of nervous system are distinguished: the somatic and the autonomous . The former would deal with the connection between the extremities of the body and the brain, while the latter would deal with reflex and involuntary actions.
Studies on the evolution of the nervous system indicate that already the edge of the sponges, despite having no nerve cells, showed the genetic basis for the appearance of this system. It is believed that the first neuron appeared 635 million years ago , in the Ediacharic period, and its evolution would run parallel to the development of the eyes and other complex senses in primitive animals.
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Parts of the nervous system
The nervous system of the human body is divided into two sets:
Central Nervous System (CNS) . Responsible for the processing of information collected by the senses and the taking of conscious actions. It is made up of the following organs:
- The brain , its most voluminous part, which encompasses the brain, divided into its two hemispheres; the cerebellum, which integrates motor functions and is in the neck region; and the brain stem that connects the spinal cord to the brain, composed of midbrain, annular bulge and spinal bulb.
- The spinal cord , prolongation of the brain that goes inside the bones of the spine and to which all the nerve endings of the body are connected.
Peripheral Nervous System (SNP) . The peripheral nervous system is made up of nerves, which run through the body and are divided into two groups:
- Cranial nerves . There are 12 pairs of nerves located, as the name implies, in the head, where they control the information relevant to the face, neck and main senses, connecting everything to the brain.
- Spinal nerves . There are 31 pairs of nerves that control the information of the trunk and limbs, connecting to the spinal cord.
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Nervous system functions
As stated before, the nervous system has the basic function of connecting nerve processing centers such as the brain , with the periphery of the extremities and the various organs of the body.
In the first place, this allows activating the muscles and promoting movement, both voluntary (walking, holding things, etc.) and involuntary (bowel movements, breathing , reflexes, etc.). Secondly, it allows sensory coordination of stimuli, such as pain and touch , and their transmission to cause responses, which is vital in the protection of the organism as a whole.
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Diseases of the nervous system
The best known of the diseases that afflict the nervous system are:
- Encephalitis . This is the name of the presence of foreign bodies in the brain, such as viruses or bacteria . Infections in this place are very delicate, since any damage to the brain can result in loss or decrease of its functions.
- Epilepsy . This congenital disease is due to excessive activation of certain corners of the brain, which respond to external stimuli in a disorderly manner and generate seizures, uncoordination and slowing down.
- MS . Differentiated between multiple and lateral, it is a series of congenital disorders in which neurons lose myelin, a layer that covers them and guarantees the effective transmission of information. This translates into loss of voluntary movement capacity and even perceptual alterations.
- Alzheimer’s . It is the most common form of senile dementia, which affects the areas of the brain linked to recent memory and language , causing progressive deterioration of cognitive functions, preventing speech, writing, reading, or simply recognizing the immediate reality. It starts at age 60 and currently has no cure.
- Parkinson ‘s disease . It is a congenital disease that causes a decrease in dopamine in the nervous system, preventing nerve coordination and generating involuntary movements, as well as sleep disorders, depression and difficulties in chewing, talking or swallowing.
