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NERVOUS SYSTEM

505313-L LLP-1-2009-1-IT-KA2-KA2MP. A journey around the Central. NERVOUS SYSTEM. The division of the nervous system. The nervous system is divided into the central nervous system (CSN) and pheripheral nervous system(PNS)

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NERVOUS SYSTEM

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  1. 505313-L LLP-1-2009-1-IT-KA2-KA2MP A journey around the Central NERVOUS SYSTEM

  2. The divisionof the nervoussystem • Thenervoussystemisdividedintothecentralnervous system (CSN) and pheripheral nervous system(PNS) • The brain and spinal cord make up the central nervous system (CSN).The brain is connected to the spinal cord, which runs from the neck to the hip area. The spinal cord carries nerve messages between the brain and the body. • The nerves that connect the CNS to the rest of the body are called the pheripheral nervous system(PNS)

  3. The centralnervoussystem • The central nervous system (CSN) includes the brain and the spinal cord. • The spinal cavity contains the spinal cord, while the head contains the brain. • The brain is protected by the skull and the spinal cord by vertebrae. • The blood - brain barrier proctects the brain from chemical intrusion from the rest of the body. • Blood flowing into the brain is filtered so that many harmful chemicals cannot enter the brain. skull vertebrae

  4. The CNS is enclosed and protected by meninges, a three – layered system of membranes called dura mater, arachnoid and pia mater. • The region between the aracnoid and pia mater is filled with cerebrospinalfluid. (CSF). • Both the spinal cord and the brain are made up of white matter (60%) and grey matter (40%) where the colors, white and grey, refer to parts of neurons in the human nervous system. • White matter consists of axons where each axon is coated with myelin. Grey matter consists of the cell body along with their dendrites and synapses.

  5. Exercise 1. Unscramble the words and then match each one to a definition • LULSK A It protects the brain • RERVBTEA B It is filtered in the brain • DHAE C It protects the CNS • EGSMINN D It is grey and white • TERMAT E They protect the spinal cord • OLBOD F It contains thebrain • Exercise 2. Complete each description with the correct word. • ……………………….are three – layered membranes. • The nerves that connect the CNS to the rest of the body form the…………... • The brain and the spinal cord make up the ………………….. • The…………………..runs from the neck to the hip area. • The……………is divided into CNS and PNS. • The………………..contains the spinal cord .

  6. Exercise 3. Write the correct name on each line

  7. braincells The brain and spinal cord are made up of many cells, including neurons and glial cells. Neurons are cells that send and receive electro-chemical signals to and from the brain and nervous system. There are about 100 billion neurons in the brain. There are many more glial cells; they provide support functions for the neurons, and are more numerous than neurons. There are many types of neurons. They vary in size from 4 microns (.004 mm) to 100 microns (.1 mm) in diameter. Their length varies from a fraction of an inch to several feet.

  8. NEURONS • Neurons are nerve cells that transmit nerve signals to and from the brain at up to 200 mph. • The neuron consists of a cell body (or soma) with branches called dendrites and an extension called axon, which conducts the nerve signal. At the other end of the axon, the axon terminals transmit the electro-chemical signal across a synapse (the gap between the axon terminal and the receiving cell). • A typical neuron has about 1,000 to 10,000 synapses, that is, it communicates with 1,000-10,000 other neurons, muscle cells and glands. • The word "neuron" was coined by the German scientist Heinrich Wilhelm Gottfried von Waldeyer-Hartz in 1891.

  9. BRAIN NEURONS

  10. The cell body (soma) contains the neuron's nucleus (with DNA and typical nuclear organelles). Dendrites branch from the cell body and receive messages. • The nucleus is the organelle in thecell body of the neuron that containsthe genetic material of the cell. • Dendrites are the branches of the neuron that receive messages.

  11. The axon isa long extension of a nerve cell. It takes information away from the cell body. Bundles of axons are known as nerves. Dendrites bring information to the cell body. • Myelin covers and insulates the axon, except for periodic breaks called “nodes of Ranvier”. It increases the speed of the message along the axon. It is produced by the Schwann's cells and consists of lipids and proteins.

  12. Exercise 4. Write the correct name on each line

  13. GLIAL CELLS • Glial cells make up 90 per cent of the brain's cells. Glial cells are nerve cells that don't carry nerve impulses. The various glial cells (meaning “glue”) perform many important functions, like the digestion of dead neurons, the production of myelin for neurons, physical and nutritional support for neurons. • Types of glial cells include Schwann's Cells, Satellite Cells, Microglia, Oligodendroglia, and Astroglia.

  14. Exercise 5. Unscrable the words and then match each one to a definition • AGILL A They send and receive electro – chemical signals. • PENSYAS B It is a long extension of a nerve cell. • NEMILY C They bring information to the cell body. • SENROUN D This cell provides support functions for neurons • TRINDESDE E It surrounds and insulates the axon • NOXA F It is the gap between the axon terminal and the receiving cell Exercise 6. Answer the following questions Which are the cells that make up the brain and spinal cord? What’s the difference between them? Which are the three parts that make up the neuron? What are dendrites? What’s the axon? What’s the function of myelin?

  15. Exercise 7. Read the following sentences and decide if they are true or false. Correct the false ones. • 1. Only glial cells make up the brain. TF • 2. Glial cells transmit and receive electro signal to and from the brain. TF • 3. The brain contains billions of neurons. TF • 4. The number of glial cells is the same as the number of neurons. TF • 5. All the neurons have the same size and length. TF • 6. The neuron is made up of three parts. TF • 7. The soma is the central part of the neuron. TF • 8. Dendrites are branches that lead the nerve signal to the brain. TF • 9. The axon takes information away from the cell body. TF • 10. Myelin is a substance that insulates the axon. TF

  16. THE BRAIN The brain has three main parts: the cerebrum, the cerebellum, and the brain stem (medulla). • The brain is one of the largest organs of the body. At birth, it weighs less than a pound. • As a child grows, the number of cells remain stable, but the cells grow in size and the number of connections increases. The human brain reaches its full size at about 6 years of age. An adult brain weighs about 3 pounds and has more than 100 billion neurons. • The brain is very soft, with a consistency similar to soft gelatine. • At the age of 20, a man has around 176,000 km and a woman about 149,000 km of myelinated axons in their brain. • All of the activities of the body are devoted to the care and protection of the brain. It is only 2% of the body's weight, it uses 20% of the oxygen supply and gets 20% of the blood flow. • Blood vessels (arteries, capillaries, and veins) supply the brain with oxygen and nourishment, and take away wastes. If brain cells do not receive oxygen for 3 to 5 minutes, they begin to die. • Cerebrospinal fluid (CSF) surrounds the brain. • The brain has four main parts: the cerebrum, the diencephalon, the cerebellum and the brain stem (called medulla).

  17. THE CEREBRUM • The cerebrum is the largest portion of the brain. It is divided by a deep longitudinal fissure into two cerebral hemispheres: right and left. • The two hemispheres are two separate entities, but they are connected by a band of white fibers, called the corpus callosum that provides a communication pathway between them. • Each hemisphere is specialized for some behaviors.

  18. Each hemisphere is dominant for other behaviors. • For example it appears that therightemisphereis dominantforspatial abilities, face recognition, visual imagery and music. • The left emisphere is more dominant for calculations, math and logical abilities.

  19. The right side of the brain controls muscles on the left side of the body and the left side of the brain controls muscles on the right side of the body. Also, in general, sensory information from the left side of the body crosses over to the right side of the brain and information from the right side of the body crosses over to the left side of the brain. Therefore, damage to one side of the brain will affect the opposite side of the body.

  20. Exercise 8. Complete the sentences with the right word: • The brain is divided into the right………………… and the left …………………… • Each part is specialized for some ……………………………………. • The two parts communicate through the ………………………………… • The …………………. side of the brain controls the left side of the body and the ………………….. ……side of the brain controls the right side of the body • Damage to one side of the brain affects the ………………………….. side of the body • The left hemisphere is dominant for …………………. abilities and …………………. , while the right hemisphere is …………………… for……………………..imagery and……………………… abilities

  21. The cerebrum is divided into four lobes: • TheFrontal Lobe of the Cerebrum is the top, front region of each of the cerebral hemispheres. It is used for reasoning,emotions, judgment and voluntary movement. • TheParietal Lobe of the Cerebrum is the middle lobe of each cerebral hemisphere between the frontal and occipital lobe; it contains important sensory centres, located at the upper rear of the head. • TheTemporal Lobe of the Cerebrum is the region at the lower side of each cerebral hemisphere; it contains centres of hearing and memory, located at the sides of the head. • The Occipital Lobe of the Cerebrum is the region at the back of each cerebral hemisphere that contains the centres of vision and reading ability, located at the back of the head.

  22. Exercise 9 Here is a short review about the 4 lobes of the brain. Take a look at this figure and then answer the questions. The numbers on the figure correspond to the number of the question. • 1. The lobe of the brain important for vision is called ................ • 2. The lobe of the brain important for the sense of touch is called ….......... • 3. The lobe of the brain important for hearing is called…............... • 4. The lobe of the brain important for reasoning and problem- • solving is called………………

  23. The brain weight in men is about 11-12% heavier than the brain weight in women, but this doesn’t mean that men are more intelligent than women. • Remember: thebrain size doesn’t correspond to intelligence. • Many behavioral differences exist between men and women. For example, it seems that women are better in certain language abilities and men are better in certain spatial abilities. • Many studies have found differences in the right and left cerebral hemispheres to suggest that male and female brains are different. But few of these experiments have found important differences between men and women.

  24. Exercise 10. Read the sentences and choose the correct statement • Babies’ brain is very heavy / quite light • The number of brain cells increases / doesn’t increase as a child grows • Men’s brain is heavier / lighter than women’s brain • The brain consists of soft / hard substance • Brain cells can / can’t resist for a long time without oxygen

  25. THE DIENCEPHALON • The diencephalon is centrally located and is surrounded by the cerebral hemispheres. • It includes the thalamus, the hypothalamus, and the epithalamus. • The thalamus, about 80 percent of the diencephalon, consists of two oval masses of grey matter that serve as relay stations for sensory impulses, except for the sense of smell, going to the cerebral cortex. • The hypothalamus is a small region below the thalamus, which plays a key role in maintaining homeostasis because it regulates many visceral activities. • The epithalamus is the most dorsal portion of the diencephalon and is involved with the beginning of puberty and rhythmic cycles in the body. It is like a biological clock.

  26. THE CEREBELLUM • The cerebellum, the second largest portion of the brain, is located below the occipital lobes of the cerebrum. • It consists of two deeply-convoluted hemispheres which make up about 10% of the weight of the brain. • It contains as many neurons as all the rest of the brain. • Three paired bundles of myelinated nerve fibers, called cerebellar peduncles, form communication pathways between the cerebellum and other parts of the central nervous system.

  27. Exercise 11. Complete each description with the correct word. • The diencephalon is surrounded by the………………….. • The diencephalon includes the ……………..,the hipothalamus and the epithalamus • ……………… is a small region below the thalamus. • The …………….. is involved with the onset of puberty • The cerebellum is located below the……………….of the cerebrum. • ……………contains as many neurons as all the rest of the brain combined. • ( cerebellum –epithalamus– occipital lobes – thalamus – hipothalamus – cerebral hemisphery )

  28. THE BRAINSTEM • The brain stem is the region between the diencephalon and the spinal cord • It consists of three parts: the midbrain, the pons, and the medulla oblongata. • The midbrain is the most superior portion of the brain stem and is the smallest region of the brain that acts as a sort of relay station for auditory and visual information. • The midbrain controls many important functions such as the visual and auditory systems as well as eye movement. • The pons is the middle portion of the brain stem and • connects the medulla to the cerebellum and helps coordinate movement on each side of thebody. • The medulla is located directly above the spinal cord and controls many vital autonomic functions such as heart rate, breathing and blood pressure. .IAll the ascending (sensory) and descending (motor) nerve fibers that connect the brain and spinal cord pass through the medulla.

  29. THE SPINAL CORD • The spinal cord is a bundle of nerves that connects the brain to other parts of the body. • Itis about 43-45 cm long and as wide as a human finger • The spinal cord is divided into 31 segments with each segment giving rise to a pair of spinal nerves • The spinal cord has two main functions:

  30. It carries information: sensory information from the peripheral nervous system to the brain and motor information from the brain to our various skeletal muscles, cardiac muscles, smooth muscles and glands.

  31. 2. It works as a reflex center. • The. reflexes are responses to stimuli that do not require conscious thought and so they occur more quickly than reactions that require thought processes. Many reflexes are mediated in the spinal cord without going to the higher brain centers. • For example, with the withdrawal reflex, the reflex action withdraws the affected part before you are aware of the pain.

  32. Exercise 12.Read the following sentences and decide if they are true or false • Correct the false ones • 1.The brain stem consists of four parts.TF • 2.The brain stem is the region beetween the diencephalon and the cerebrum. TF • 3.The midbrain is the superior portion of the brain stem.TF • 4. The medulla oblongata extends upwards from the pons.TF • 5. The spinal cord carries motor and sensory information.TF • 6. The reflexes are responses to stimuli .TF

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