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The central nervous system (CNS) is the management center of the entire organism - it consists of the brain and the spinal cord, and it is these two structures that determine what stimuli we receive from the environment, as well as how our planned movements or how often do we breathe. But what exactly are the components of the central nervous system? What are the diseases of the CNS?

The central nervous systemconsists of two main components, the brain (commonly referred to as the brain) and the spinal cord. The main component that builds the central nervous system are nerve cells, i.e. neurons - it is estimated that there are about 100 billion of them in the brain alone. In addition to them, the structures of the CNS are also made of various support cells (referred to as glial cells) - these include, among others:

  • astrocytes (cells dealing, among others, with the degradation of neurotransmitters and the removal of unnecessary metabolites from the vicinity of neurons)
  • oligodendrocytes (cells involved in the production of myelin sheaths)
  • ependymal cells (cells that line, among others, the structures of the ventricular system, which both produce and resorb the cerebrospinal fluid)

Central nervous system: development

The beginning of the development of the central nervous system takes place quite early, already on the 16th day after fertilization. This is when the nerve plate is formed from the ectoderm. Due to the proliferation of cells on its periphery, a neural gutter is formed. Then a neural tube is produced, which is completely closed by the end of the fourth week of pregnancy. Within the coil, four bubbles start to form, which are:

  • forebrain (it is the basis of the forebrain and interbrain)
  • midbrain
  • hindbrain (from which the hindbrain and the medulla later separate)

During pregnancy, individual parts of the central nervous system increase in size, and their various elements develop. Among the important events that take place during the development of the central nervous system, it is worth mentioning here the formation of the first synaptic connections or the formation of the first synaptic connections in the sixth week of pregnancy.the beginning of the formation of myelin sheaths in 11-12 week of pregnancy.

There is probably no need to explain the fact that just as the structure and functions of the central nervous system are quite complicated, so is the process of its development - various pathologies that interfere with the development of the CNS (e.g. various harmful factors, exposed to the fetus during pregnancy) may result in birth defects of the central nervous system, such as

  • brainless
  • spina bifida
  • formation of only one hemisphere of the brain

Central nervous system: brains

The brain consists of several different structures, which are distinguished both by their structure and their functions. In general, the following elements can be distinguished in the brain protected by the structures of the skull:

  • Kresomózgowie
  • interbrain
  • midbrain
  • core extension
  • cerebellum

If we look at any diagram depicting the brain, the first thing that catches the eye - the hemispheres of the brain - corresponds to the forebrain. In addition to the above-mentioned structures, this part of the central nervous system also includes the commemorations of the brain (which include the corpus callosum), the basal ganglia, the hippocampus and the lateral ventricles belonging to the cerebral ventricular system.

Within the forebrain there are four lobes, which are:

  1. frontal lobe: it is located in the front of the forebrain and corresponds to, inter alia, for maintaining attention, short-term memory, motivational processes and planning
  2. parietal lobe: located next to the frontal lobe and responsible for the integration of various sensory stimuli, such as tactile stimuli from various parts of the body
  3. temporal lobe: located in the lateral parts of the forebrain, its function is, inter alia, analysis of auditory sensations, in addition, the temporal lobe is also related to our memory and emotions
  4. occipital lobe: located in the posterior terminal part of the forebrain, it plays a role in the analysis of visual stimuli

Above are some components of the forebrain that are also worth mentioning. The corpus callosum is a collection of numerous nerve fibers thanks to which the right and left hemispheres of the brain can communicate with each other (generally considered to be the largest concentration of white matter in the entire brain).

The base nuclei are, in turn, the structures responsible for e.g. for the way our motor activities proceed.

The hippocampus is considered to be an element of the limbic system andit is mainly related to various memory processes.

Central Nervous System: Interbrain

Belonging to the CNS interbrain is located between the endbrain and midbrain. It includes, among others the thalamus and hypothalamus as well as the third ventricle of the ventricular system, apart from that, the pineal gland and the pituitary gland are also considered parts of the diencephalon.

Like all parts of the central nervous system, the diencephalon plays a number of important roles. It is there that the centers that control the course of metabolism are located. The pituitary gland and hypothalamus are one of the basic endocrine glands (they secrete hormones that control the function of other glands, such as the thyroid gland, gonads or adrenal glands).

The pineal gland is involved in the regulation of the sleep-wake rhythm, in addition, there are various centers in the dumbrain, the task of which is to integrate various sensory stimuli reaching the CNS.

Central nervous system: midbrain

Within the midbrain there are other elements of the ventricular system of the brain - they are:

  • the brain's water supply (Latinaquaeductus cerebri ) filled with cerebrospinal fluid
  • fourth chamber

The midbrain has numerous connections to the rest of the brain, and its main functions are to control eye movements and reflexes related to the sense of sight and hearing. The midbrain, along with the medulla and the bridge, together form the structure known as the brainstem.

Central nervous system: bridge

As mentioned above, the bridge is part of the brain stem. His tasks include influencing the course of various motor activities, and in addition, the bridge is also the connection between the cerebellum and the cerebral cortex belonging to the endbrain.

Central nervous system: medulla

The medulla is the third and last component that builds the brain stem. Within this structure there are numerous centers that control basic life processes - such as the center that controls respiration or the center that regulates the value of arterial blood pressure. In addition, the task of the medulla is also to mediate the transmission of nerve impulses between the spinal cord and the rest of the central nervous system.

Central nervous system: cerebellum

The name of the cerebellum did not come out of nowhere - this structure resembles the reduced hemispheres of the brain. Like the cerebellum, the cerebellum has two hemispheres. The functions of this part of the central nervous system areextremely important - it is the cerebellum that is responsible for maintaining our balance or the precise course of our movements. In addition, this structure is involved in coordinating the course of eye movements and it has an impact on learning new motor activities by us.

Central nervous system: spinal cord

The spinal cord is a kind of intermediary - it takes part in the transmission of impulses between the higher levels of the central nervous system (i.e. the brain) and the peripheral nervous system - such impulses are, among others, signals from tactile, pain and thermal receptors.

The spinal cord runs along the entire length of the spinal canal - typically human spinal cord ends at the level of the first lumbar vertebra. The spinal cord is divided into segments:

  • 8 cervical
  • 12 pectoral
  • 5 lumbar
  • 5 cross
  • 1

One pair of spinal nerves depart from each of these segments.

Central nervous system: diseases

Due to the important functions of the central nervous system, the symptoms of its diseases can in an extremely dramatic way impair the normal functioning of patients. There are many more CNS diseases than one could possibly imagine - examples of units that may concern this particular part of the nervous system include:

  • various types of infections (such as, for example, meningitis, but also encephalitis or brain abscess, in addition, CNS involvement may occur even in the course of various sexually transmitted diseases - here, an example can be central syphilis nervous system)
  • stroke, cerebellar stroke or stroke (which may be ischemic or hemorrhagic)
  • neurodegenerative diseases (such as Alzheimer's disease or Parkinson's disease)
  • neoplastic diseases (both benign and malignant tumors can develop within the central nervous system)
  • injuries of the central nervous system
  • birth defects (anencephaly is one of the most serious of these problems)
  • genetically determined diseases (such as e.g. amyotrophic lateral sclerosis or Huntington's disease)
  • neurodevelopmental disorders (which include ADHD and autism spectrum disorders)

Specific symptoms, which are caused by diseases of the central nervous system, it is impossible to list here - it all depends on the type ofthe individual will develop exactly in a sick person.

Sometimes a patient's ailments develop very insidiously and increase their severity very slowly - this is the case, for example, in the course of various neurodegenerative diseases. Other individuals can lead to sudden and severe neurological deficits - an example of a disease that can cause them is a stroke.

About the authorBow. Tomasz NęckiA graduate of medicine at the Medical University of Poznań. An admirer of the Polish sea (most willingly strolling along its shores with headphones in his ears), cats and books. In working with patients, he focuses on always listening to them and spending as much time as they need.

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Category:

Neurology