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Functions of the central nervous system

Source: BruceBlaus, Wikimedia Commons, licencja: CC BY 3.0.

Link to the lesson

Before you start you should know
  • information in the nervous system is transferred via neurons;

  • activities of the nervous system (autonomic nervous system) direct functions of our body without us being conscious of it;

  • information from inside the body and from the environment via nerves can reach the central nervous system.

You will learn
  • to explain where the encephalon is located, its structure and functions;

  • to compare the functions of the cerebral hemispheres;

  • to explain the significance of training in brain development;

  • to explain where the spinal cord is located, its structure and functions.

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Nagranie dźwiękowe dotyczące czynności ośrodkowego układu nerwowego.

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.

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Ilustracja przedstawia mózgowie. Mózgowie tworzą następujące elementy: 1. the cerebral cortex , 2. brainstem , 3. spinal cord , 4. encephalon , 5. brain , 6. cerebrum , 7. central nervous system (CNS)
Central nervous system
Source: GroMar Sp. z o.o., licencja: CC BY-SA 3.0.

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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Protection of the central nervous system
Source: Tomorrow Sp. z o.o., licencja: CC BY 3.0.

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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View of the brain from above (on the left), cross section through one of the hemispheres along the motor cortex (on the right).
Source: Dariusz Adryan, licencja: CC BY 3.0.

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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Cerebellum and the brain stem
Source: Tomorrow Sp. z o.o., licencja: CC BY 3.0.
Task 1

Can cerebellum influence the reading efficiency? Answer this question.

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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Location of the spinal cord
Source: Tomorrow Sp. z o.o., licencja: CC BY 3.0.
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Exercise 1
Select the correct sentences. Możliwe odpowiedzi: 1. The central nervous system controls vital functions of the body, 2. Conditioned reflexes are stable, unchangeable and inborn, 3. Involuntary reflexes are learnt and when unused, they disappear, 4. The spinal cord is composed of the gray and white matter

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.

Homework
Task 2.1

Suggest two activities suitable for elderly people to do in order to maintain the mental ability.

Keywords

encephalon, spinal cord, central nervous system

Glossary

effector
effector
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Nagranie dźwiękowe słówka effector

efektor – narząd wykonawczy, który reaguje na przesłany impuls nerwowy

brain
brain
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Nagranie dźwiękowe słówka brain

mózg – część mózgowia złożona z 2 półkul mózgowych; u człowieka posiada szczególnie dobrze rozwiniętą korę mózgową odpowiedzialną za czynności psychiczne

cerebellum
cerebellum
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Nagranie dźwiękowe słówka cerebellum

móżdżek - część mózgowia odpowiedzialna za koordynację i precyzję ruchów, postawę, napięcie mięśni

meninges
meninges
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Nagranie dźwiękowe słówka meninges

opony mózgowe - błony łącznotkankowe (miękka, pajęcza, twarda) ochraniające mózgowie i rdzeń kręgowy

brain stem
brain stem
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Nagranie dźwiękowe słówka brain stem

pień mózgu - część mózgowia, w skład której wchodzi m.in. rdzeń przedłużony; odpowiada za kontrolę podstawowych czynności życiowych organizmu

cerebrospinal fluid
cerebrospinal fluid
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Nagranie dźwiękowe słówka cerebrospinal fluid

płyn mózgowo‑rdzeniowy – przesącz osocza krwi, który chroni mózgowie i rdzeń kręgowy, zaopatruje je w substancje odżywcze i odbiera od nich produkty przemiany materii

medulla oblongata
medulla oblongata
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Nagranie dźwiękowe słówka medulla oblongata

rdzeń przedłużony – część mózgowia podtrzymująca podstawowe funkcje życiowe