505313-L LLP-1-2009-1-IT-KA2-KA2MP
This project has been funded with the support from the European Commission.
This communication reflects the views only of the author, and the Commission
cannot be held responsible for any use which may be made of the information
contained therein.
The division of the nervous system
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The nervous system is divided into
the central nervous system (CSN)
and pheripheral nervous
system(PNS)
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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.
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The nerves that connect the CNS to
the rest of the body are called the
pheripheral nervous system(PNS)
The central nervous system
 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.
skull
 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.
vertebrae
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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
cerebrospinal fluid. (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.
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Exercise 1. Unscramble the words and then match each one to a definition
1.
6.
LULSK
RERVBTEA
DHAE
EGSMINN
TERMAT
OLBOD
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Exercise 2. Complete each description with the correct word.
2.
3.
4.
5.
A It protects the brain
B It is filtered in the brain
C It protects the CNS
D It is grey and white
E They protect the spinal cord
F It contains the brain
1.
……………………….are three – layered membranes.
2.
The nerves that connect the CNS to the rest of the body form the…………...
3.
The brain and the spinal cord make up the …………………..
4.
The…………………..runs from the neck to the hip area.
5.
The……………is divided into CNS and PNS.
6.
The………………..contains the spinal cord .
Exercise 3. Write the correct name on each line
brain cells
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.
NEURONS
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Neurons are nerve cells that transmit nerve signals to and from the brain at up to 200 mph.
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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).
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A typical neuron has about 1,000 to 10,000 synapses, that is, it communicates with 1,00010,000 other neurons, muscle cells and glands.
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The word "neuron" was coined by the German scientist Heinrich Wilhelm Gottfried von
Waldeyer-Hartz in 1891.
BRAIN NEURONS
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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 the
cell body of the neuron that
contains the genetic material of the
cell.
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Dendrites are the branches of the
neuron that receive messages.
•
The axon is a 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.
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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.
Exercise 4. Write the correct name on each line
GLIAL CELLS
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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.
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1.
2.
3.
4.
5.
6.
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
1.
2.
3.
4.
5.
6.
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?
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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
THE BRAIN
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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).
THE CEREBRUM
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The cerebrum is the largest portion
of the brain. It is divided by a deep
longitudinal fissure into two
cerebral hemispheres: right and
left.
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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.
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Each hemisphere is specialized for
some behaviors.
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Each hemisphere is
dominant for other
behaviors.
For example it appears
that
the
right
emisphere is dominant
for spatial abilities,
face
recognition,
visual imagery and
music.
The left emisphere is
more dominant for
calculations, math and
logical abilities.
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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.
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Exercise 8. Complete the sentences with the right word:
1.
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
2.
3.
4.
5.
6.
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The cerebrum is divided into four lobes:
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The Frontal 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.
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The Parietal 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.
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The Temporal 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.
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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.
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 problemsolving is called………………
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The brain weight in men is about 1112% heavier than the brain weight in
women, but this doesn’t mean that
men are more intelligent than women.
Remember: the brain 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.
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Exercise 10. Read the sentences and choose
the correct statement
1. Babies’ brain is very heavy / quite light
2. The number of brain cells increases / doesn’t
increase as a child grows
3. Men’s brain is heavier / lighter than women’s
brain
4. The brain consists of soft / hard substance
5. Brain cells can / can’t resist for a long time
without oxygen
THE DIENCEPHALON
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The diencephalon is centrally located
and is surrounded by the cerebral
hemispheres.
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It includes the thalamus, the
hypothalamus, and the epithalamus.
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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.
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The hypothalamus is a small region
below the thalamus, which plays a key
role in maintaining homeostasis
because it regulates many visceral
activities.
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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.
THE CEREBELLUM
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The cerebellum, the second
largest portion of the brain, is
located below the occipital
lobes of the cerebrum.
It consists of two deeplyconvoluted 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.
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Exercise 11. Complete each description with the correct word.
1. The diencephalon is surrounded by the…………………..
1.
The diencephalon includes the ……………..,the hipothalamus and the
epithalamus
1. ……………… is a small region below the thalamus.
1.
The …………….. is involved with the onset of puberty
1. The cerebellum is located below the……………….of the cerebrum.
1. ……………contains as many neurons as all the rest of the brain combined.
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( cerebellum –epithalamus– occipital lobes – thalamus – hipothalamus
– cerebral hemisphery )
THE BRAIN STEM
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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.
THE SPINAL CORD
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The spinal cord is a bundle of
nerves that connects the brain to
other parts of the body.
It is 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:
1.
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.

2. It works as a reflex center.
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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.
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• 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