We explain what the nervous system is and what its functions are. Parts of the nervous system and most common diseases.
What is the nervous system?
The nervous system is called set of organs and control and information structures of the human body made up 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 humans and most chordate animals, arthropods, mollusks, flatworms and cnidarians. Other animal groups, such as protozoa, porifera and plants, however, do not have a differentiated nervous system.
This device for transmitting chemical and electrical energy runs through the entire body and allows the coordination of body movements and actions both conscious and reflexive, from which two types of nervous system are distinguished: the somatic and the autonomic. The first would deal with the connection between the body's extremities and the brain, while the second deals with reflex and involuntary actions.
Studies on the evolution of the nervous system indicate that the sponge phylum, despite not having nerve cells, showed the genetic bases for the appearance of this system. It is believed that the first neuron appeared 635 million years ago in the Ediacaran period, and its evolution would run parallel with the development of eyes and other complex senses in primitive animals.
See also: Locomotor system
Parts of the nervous system
The nervous system of the human body is divided into two sets:
- Central Nervous System (CNS) Responsible for processing information collected by the senses and taking conscious actions. It is made up of the following bodies:
- 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 the midbrain, pons and medulla oblongata.
- The spinal cord. Extension 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 (PNS) 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 their name indicates, in the head, where they control information pertinent to the face, neck and main senses, connecting everything to the brain.
- Spinal nerves There are 31 pairs of nerves that control information from the trunk and extremities, connecting to the spinal cord.
Functions of the nervous system
As mentioned before, the nervous system has the basic function of connect nerve processing centers like the brain with the periphery of the limbs and the various organs of the body.
Firstly, this allows you to activate the muscles and promote movement, both voluntary (walking, holding things, etc.) and involuntary (bowel movements, breathing, reflexes, etc.). In second place, allows sensory coordination of stimuli, such as pain and touch and its transmission to cause responses, which is vital in the protection of the organism as a whole.
Nervous system diseases
The best known diseases that affect the nervous system are:
- Encephalitis This is the name given to 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 reduction 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 disordered manner and generate seizures, incoordination and slowing down.
- Sclerosis 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 results in loss of the capacity for voluntary movement and even perceptual alterations.
- Alzheimer's disease. It is the most common form of senile dementia, which affects the areas of the brain linked to recent memory and language, producing progressive deterioration of cognitive functions, preventing speaking, writing, reading, or simply recognizing immediate reality. It starts at age 60 and at the moment there is no cure.
- Parkinson's disease. It is a congenital disease that causes a decrease in dopamine in the nervous system, preventing nervous coordination and generating involuntary movements, as well as sleep disorders, depression and difficulties chewing, speaking or swallowing.
