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Central nervous system

The central nervous system guides the functioning of the internal organs of a body, analyzes the stimuli that reach the organism, controls its reactions, is responsible for the development of brain functions, such as associating, memorizing, learning. It is made up of concentrations of nerves arranged in a specific way. The bodies of neural cells are attached to each other, creating grey matter. Bundles of axons create the white matter. The central nervous system is composed of the encephalon and the spinal cord.

The central nervous system as the control centre for the vital functions of the body must be especially protected against injuries and against external factors. The encephalon and the spinal cord are protected by:

• bone elements – cranial bones protect the encephalon, whereas the spinal canal protects the spinal cord;

• cerebrospinal fluidcerebrospinal fluidcerebrospinal fluid, a derivative of blood plasma, which cushions shakes and provides neural cells with nutrients, as well as receives from them products of metabolism;

• 3 membranes of connective tissue called meningesmeningesmeninges.

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Ilustracja przedstawia anatomiczne elementy chroniące ośrodkowy układ nerwowy wraz z jej najważniejszym organem jakim jest mózg. Mózg ma postać szarych zwojów. Móżdżek kreskowanego półkola. Pień mózgu i rdzeń kręgowy w kolorze ciemnobrązowym. Najbardziej zewnętrzną osłonę ośrodkowego układu nerwowego stanowi czaszka człowieka. Kierując się do wewnątrz kolejne warstwy ochronne stanowią: 1. Dura mater - it is in contact with bones protecting the brain and spinal cord. 2. Arachnoid matter. 3. Pia mater - it is rich in blood and firmly adheres to the surface of the brain and the spinal cord 4. Space field with cerebrospinal fluid. 5. Spinal cord. 6. Brain

Brain

The brainbrainbrain is the biggest part of the encephalon. Its outer layer, which is the cerebral cortex, is composed of a gray matter and is characterised by the specific folds. Underneath the cerebral cortex there is a white matter. Brain, even though it is only 2% of the body mass, uses 20% of the energy our body produces. The brain is composed of dozens of millions of neural cells, and each single cell can have around 25 thousands connections with other neurons. During your life, the brain can create new neural connections, thanks to which we have the ability to learn. Tasks that require performing new activities, practicing physical skills and solving theoretical problems, favour creating new connections and increase the brain efficiency. For small children, plays that require precise movements, e.g. DIY are the key factor for brain development. For older children, it is important to develop the brain via reading, writing, speaking and practising all tasks that require gaining new skills.

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Ilustracja przedstawia mózg w rzucie z góry i przekroju bocznym. Pas przebiegający przez środek mózgu w rzucie z góry oznacza korę ruchową, motor cortex. W rzucie przekroju bocznego widać zarys kory mózgowej, obok kolorowe odcinki symbolizują narządy, które dany odcinek kory koordynuje. Są to głównie kończyny, palce, toes, części twarzy, parts of the face szyja, język, tongue. Kora mózgowa kieruje ich świadomymi ruchami. Zaznaczone są fragmenty, które odpowiadają za palce u stóp, nogi, legs, tułów, torso, ramiona, arms, ręce, hands, palce u dłoni, fingers, kciuk, thumb, szyję, neck, brwi, eyebrows, oko, eye, twarz, face, wargi, lips język, gardło, throat, żuchwa, jaw i szczęka, jaw.

Cerebellum and the brain stem

The second biggest part of the encephalon is the cerebellumcerebellumcerebellum. Similarly to the brain it has a folded cortex and 2 hemispheres. The cerebellum is responsible for skeletal muscle tonus, maintaining body balance and motor coordination, e.g. when eating with a fork and knife, and when learning to ice‑skate.

Between the cerebellum and the spinal cord there is the brain stembrain stembrain stem. Its part is the medulla oblongatamedulla oblongatamedulla oblongata. It is the centre for reflexes which condition your life and are not dependant on our will, e.g. breathing, heartbeat, chewing and swallowing, sucking and metabolism. The medulla oblongata injury can lead to death.

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Ilustracja przedstawia mózgowie w przekroju poprzecznym. U góry zwoje kory mózgowej. Kolorem żółtym oznaczono pofałdowany móżdżek (cerebellum), który znajduje się w prawej, tylnej części przekroju, pień mózgu (brain stem) jest czerwony z białymi komorami i znajduje się w centralnej części przekroju mózgowia.

Spinal cord

The spinal cord is cylindrical and is located in the spinal canal of the spine. Just like the encephalon, it is composed of the gray and white matter. Unlike the encephalon, it has the white matter on the outside, whereas the gray matter is on the inside. In a transverse cross‑section, the gray matter has the shape of the letter H. Inside the spinal cord there is a central canal filled with cerebrospinal fluid, which is also present in the area between the spinal cord and its meninges. From the spinal cord, in a symmetrical way, on both sides of the spine, there are 31 pairs of spinal nerves which belong to the central nervous system. The spinal cord acts as an intermediary in transferring information which runs from the receptors and from the encephalon to the effectorseffectoreffectors. As the neural centre for involuntary (inborn) reflexes, it directs those functions of the body which happen without us being aware of them.

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Ilustracja przedstawia schematycznie położenie rdzenia kręgowego. Dwa brązowe kręgi piersiowe. Za ich trzonami biegnie zielony rdzeń kręgowy. Na boki wystają fioletowe nerwy rdzeniowe. The illustration shows a schematic representation of the position of the spinal cord. Two brown breast circles. Behind their stems runs a green spinal cord. Violet spinal nerves protrude from side to side. Podpisano: spinal cord; spinal canal; vertebra; spinal nerve

Summary

• The central nervous system is composed of the encephalon and the spinal cord.

• The encephalon consists of the brain, the cerebellum and the brain stem.

• The cerebral cortex is the outer part of the brain. It is there where we have the centres for coordinating life functions, associating information, interpreting stimuli and directing movements that are dependant on our will (voluntary).

• The cerebellum controls the tension of the muscles and is responsible for maintaining balance.

• In the medulla oblongata there are centres responsible for maintaining basic life functions.

• The spinal cord acts as an intermediary in transferring information between the encephalon and other parts of the body.

• The central nervous system is protected by bones, meninges and cerebrospinal fluid.

Keywords

encephalon, spinal cord, central nervous system

Glossary