He Central Nervous System (CNS) is that composed of the brain , the spinal cord And the optic nerves. It is called"central"because it integrates information coming from the whole organism and coordinates the activity of this one.
This system has a wide variety of functions. In general, it can be said that cognitive processes , the emotions , Movement and the perception of stimuli.
Brain and spinal cord.
The brain and spinal cord are covered by a protective membrane called Meninges . This makes the CNS the most protected in the body, and serves to cushion the blows and nourish these structures.
In the subarachnoid space of the meninges, the cerebrospinal fluid . It protects our brain and maintains its metabolism. It also travels through the cavities of our brain, which are known as brain ventricles.
The basic unit of the central nervous system is the neuron . It is a special type of nerve cell that transmits electrical and chemical messages to exert different effects on its neighboring cells.
In addition to neurons are also distinguished the Glial cells , Known as the"supporting cells". They serve to support neurons, displace them, and give them oxygen and nutrients. There is more of these cells than neurons, in a ratio of 10 to 1.
The central nervous system has been studied extensively for years, but still contains many mysteries to discover.
Parts of the central nervous system
In general, the central nervous system consists of the brain and the spinal cord . Although the retina, the optic nerves, the olfactory nerves and the Olfactory epithelium . This is because they connect directly to brain tissue.
On the other hand, they are also usually spoken of two parts of the central nervous system: white matter and gray matter.
The White matter Is one that is formed by myelinated axons of neurons and oligodendrocytes.
The Myelin , Which covers the axons and makes the nerve impulses travel much faster, give a white color to the area. White matter is in the innermost areas of the brain, and in the outer areas of the spinal cord.
The gray matter or matter, on the other hand, is composed of neuronal sums (cell nuclei) and dendrites without myelin. In the brain is in the outermost layer. While in the spinal cord, it is situated in the interior.
Here you can learn more about the main components of the central nervous system:
Brain
The brain is the most complex organ in the body. It seems to be composed of about 100 billion neurons, which establish innumerable connections between them.
This organ uses 20% of the oxygen we breathe, constituting 2% of our complete weight.
The brain is usually divided into Lobes : The occipital lobe, the parietal lobe, the temporal lobe and the frontal lobe. Scientists have discovered over years of research that each of them is linked to a group of functions.
However, it should not be forgotten that this is very general. Our behaviors depend more on circuits distributed by the brain and groups of neurons than a localized portion of the brain.
The brain lobes are:
- Occipital lobe Is in the back of the brain, receive visual information and interpret it.
- Parietal lobe Are in front of the occipital lobes. They are associated with the processing of sensory information (touch, temperature, pain, taste...) and spatial perception.
- Temporal lobe Are placed on each side of the brain, behind the ears. They are important for processing auditory information, language and memory.
- Frontal lobe Is on the front of the brain. It participates in voluntary movements and coordinates with other parts of the brain for speech, organization and planning, memory, etc.
In the section of functions you can learn more about the tasks performed by each lobe.
On the other hand, cortical and subcortical structures are also often differentiated in the brain. The former are the outermost and evolutionarily new layers. While the second are the closest to the base of the skull, interior and primitive.
The cerebral cortex Has more complex and elaborate functions of primates and humans.
While subcortical structures handle simpler tasks shared by mammals ( limbic system ), And even reptiles ( brainstem ).
Spinal cord
It is a continuous structure that runs from the brain, beginning at the base of the skull, to the end of the spine.
It connects to a part of the brain called the brainstem, lodged in the spinal canal. From the marrow the different nerve roots go to the two sides of the body. Thus, it connects with the peripheral nervous system Which reaches the joints, muscles and skin.
The spinal cord transmits messages back and forth between the brain and the peripheral nerves. For example, the brain can give motor orders that travel to the spine and reach the muscles.
Or, the information that comes from the senses can move from the sensory tissues (like the skin) to the spinal cord. From there, it will reach the brain.
It also allows us to give fast motor responses, such as reflexes, without the information having to be processed in the brain. For example, when we quickly remove our hand from a very hot object.
Cranial nerves
There are 12 pairs of cranial nerves that emerge directly from the brain, passing through the holes in the skull. They serve to exchange information between the brain and other parts of the body, especially the head and neck.
Of these 12 pairs, the optics, the olfactory and the terminal are considered part of the central nervous system.
The optic nerves are behind the eyes, and carry visual information from the retina to the brain.
The olfactory nerves carry scent messages to the upper part of the nasal cavity, which is called the olfactory bulb. It transmits information to the brain.
While the role of terminal cranial nerves is not known with accuracy. Some believe it is a vestige or involved in the production of pheromones.
Functions of the central nervous system
It is enormously complex to list all the functions of the central nervous system. It has so many functions and so varied that it is more appropriate to focus on studying each region separately.
Here is a brief summary, but keep in mind that this list is not completely exhaustive.
Brain functions
The brain plays a central role in regulating most bodily functions, coordinating a wide variety of tasks.
It ranges from the secretion of hormones, the level of consciousness, the simpler movements, the perception of stimuli, the emotions, the creation of memories, to the language and the thoughts.
To perform these functions, the brain has certain areas dedicated to them. However, most of the higher functions such as problem solving, language, reasoning, or planning require different areas of the brain to work together.
We can divide the brain functions according to each lobe:
Occipital lobe
It contains the visual cortex, the area that controls visual perception. It projects information to other parts of the brain for identification and interpretation.
Parietal lobe
It integrates information that comes from the senses, such as touch or taste. It also regulates the perception of the position of the body parts themselves, and the relationship of oneself to space.
That is, it is important for spatial perception and navigation. It has also been found to be related to number recognition and mathematical calculations.
Temporal lobe
It processes some aspects of language as well as auditory information. It stores long-term memories with the help of the hippocampus. In addition, it is important in complex visual processing, such as face recognition.
It also contains the amygdala, a fundamental structure for memorizing and triggering emotions (especially negative ones).
Frontal lobe
It is associated with complex and elaborate functions. Among them are the attention, the work memory , Motivation, planning, self-control, language expression and emotional regulation.
On the other hand, there are fundamental structures of the brain that are not linked to a particular lobe. Some examples are:
Basal ganglia
The Basal ganglia , Which are found inside the brain and control voluntary movements. They are also linked to the learning of motor sequences such as learning to play an instrument or to skate.
Cerebellum
It is a structure located at the base of the brain. It is traditionally associated with balance and coordination.
In addition, it participates in fine and precise motor control, and the generation of muscular tone. However, it has been found to be involved in some types of memory, attention, spatial abilities and language.
Thalamus
It is in the center of the brain. It receives motor and sensory information and transmits it to other parts of the cerebral cortex. It is associated with awareness, level of alertness and sleep.
Hypothalamus
Hypothalamus
It is just above the brain stem and is responsible for releasing neurohormones. These are used to regulate body temperature, hunger and thirst.
Bulb
It is located below the skull, and triggers many involuntary functions such as breathing, maintaining blood pressure, sneezing, or vomiting.
Functions of the spinal cord
As already discussed, the spinal cord is the intermediary between the brain and the peripheral nervous system. It is very important in the sensory perception of the joints, muscles and skin; In addition to controlling the movement.
The spinal cord can direct movements without the involvement of the brain, as with reflexes or as we walk.
This structure can coordinate all the muscles needed to walk, intervening only the brain to initiate or interrupt the process. Just as it would intervene if they appear unforeseen, like an object that prevents to advance.
Diseases of the central nervous system
As this system is so wide and complex, a large number of different conditions can alter its functioning.
Injuries or diseases that affect this system, can cause the loss or deterioration of some of the functions mentioned. This can lead to a lower or greater degree of disability. Depending on where the damage occurs, the symptoms can vary greatly.
The main factors that can impair the functioning of the central nervous system are:
Traumas
It is any type of Damage acquired (By an intense blow, for example) in the brain or spinal cord. Depending on the injured area, the symptoms range from paralysis or motor problems to apathy or disinhibition.
Stroke
It is the interruption of blood flow to the brain. As neurons run out of oxygen, they die.
Therefore, the results are similar to those arising from trauma. However, the Stroke Can affect more specific circuits of the brain. For example, those responsible for producing or understanding the language. A stroke in these circuits can lead to aphasia.
Infections
Some microorganisms or viruses have the capacity to invade the central nervous system, as in the meningitis Or encephalitis. Viruses that can affect the central nervous system are herpes virus, herpes zoster, enteroviruses, arboviruses, etc.
Degeneration
There are conditions, in which, for reasons not yet defined, the brain or spinal cord progressively degenerate. This is what happens with dementia. Some examples are Alzheimer's, Parkinson's, Amyotrophic Lateral Sclerosis , the Huntington's Korea , etc.
Structural Neurodevelopmental Disorders
These are birth defects in which some part of the central nervous system has not developed or matured properly. This is seen in anencephaly, for example, in which the baby is born without parts of the skull, scalp and brain.
Neurodevelopmental disorders are also categorized as intellectual disability, ADHD, learning disorders (such as dyslexia), autism, or language disorder.
Tumors
Benign or cancerous tumors can affect any part of the central nervous system and cause symptoms that depend on where they appear. What produces a cyst or tumor is that it presses the tissues of its around, causing that they are compressed and increasing the intracranial pressure.
Autoimmune diseases
Sometimes the immune system may mistakenly attack healthy brain or spinal cord tissues. Mainly the myelin of some areas. This is what occurs in acute disseminated encephalomyelitis and in multiple sclerosis.
In addition, there are many diseases of the central nervous system that arise by a combination of listed factors and involvement of genes. For example, this occurs with psychiatric and psychological disorders such as depression , he Bipolar disorder wave schizophrenia .
References
- Bailey, R. (March 4, 2017). Central Nervous System Function. Retrieved from"ThoughtCo: thoughtco.com".
- Caserta, M. (s.f.). Viral infections of the central nervous system in children. Retrieved on April 3, 2017, from MSD Manual: msdmanuals.com.
- Central Nervous System. (February 20, 2015). Retrieved from WebMD: webmd.com.
- Central nervous system disease. (S.f.). Retrieved on April 3, 2017, from Wikipedia: en.wikipedia.org.
- CNS (Central Nervous System) Functions, Parts, and Locations. (S.f.). Retrieved on April 3, 2017, from emedicinehealth: emedicinehealth.com.
- Degenerative diseases and demyelination of the CNS. (May 13, 2015). Obtained from Eusalud: eusalud.uninet.edu.
- Newman, T. (March 2, 2016). Central Nervous System: Structure, Functions and Diseases. Retrieved from Medical News Today: medicalnewstoday.com.