Nervous System CLASS-5 SIMPLIFIED NOTES
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CHAPTER – 8
Our Nervous System
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What
is Nervous System ?
·
·
The nervous system helps the body to perform
all its functions .
·
The nervous system controls every movements
of the body and the working of all the organs .
·
Controls overall the functioning of the body
like memory , speech , heartbeat , breathing ,etc ….
About Brain
Γ The brain is the soft and delicate
part of the body within the skull.
Γ The space between the brain and the
skull bones is filled with a fluid.
Γ The fluid protects the brain from
jerks.
Parts of brain
Cerebrum : the cerebrum is the largest and the uppermost part
of the brain . It helps you to think,
remember and learn. It also controls the functions of the eyes and ears, nose
and tongue .
2. Cerebellum
: the cerebellum controls movements
and maintains the balance of the body .
3 Medulla : The medulla
is the lowermost part of the brain . The
medulla regulates functions such as heartbeat, circulation of the blood and breathing.
About Spinal cord
v The spinal cord links the brain and
the other parts of the body . It begins at the medulla of the brain and extends
all along the back .
v The spinal cord is protected inside
the vertebral column that is made up of 33 bones called vertebrae.
About Nerves
ΓΌ Nerves are the thread-like
structures.
ΓΌ They present in the entire body .
ΓΌ Nerves are connected either with the
brain or the spinal cord .
ΓΌ The nerves used to transfer messages
.
Voluntary and involuntary
actions
ΓΌ
An action that is controlled by an
individual is called voluntary actions.
ΓΌ Walking,
dancing, reading, etc…..
ΓΌ
An Action that does not have any control
by an individual is called involuntary actions.
ΓΌ Example – breathing, digestion of
food , beating of heart and formation of
urine .
Reflex action
Β΅ A quick response to a
stimulus is called a reflex action.
Β΅ When u
touches the hot water, u feel pain. A sensory nerve in your finger senses the
pain and quickly carries the message (impulse)
to the spinal cord.
The spinal cord too acts quickly. It sends back a
message to the arm muscles to move the arm away.
This is the reflex
action .
How do sense organs work ?
I.
Eyes – Each eyes has a lens . when we look
at an object, the light passes through the lens and the image form inside the
eyes . The image is converted into a message or impulse.
II.
Ears – we hear through the eardrum
that is inside the ear which is a
thin membrane.
III.
Nose – We smell with our nose. The nerves
inside the nose pick up the smell , convert it into a message and carry it to
the brain . the brain recognises the message and
helps us know the smell.
IV.
Tongue – the tongue has taste buds, which
sense different tastes. The taste buds are connected to nerves .
V.
Skin – we feel when something touches
on the skin . the skin is richly
supplied with the nerves .It helps us to
sense pan , temperature and feel things
.
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