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Brain structure
Nerve messages
Motor and Sensory nerves
The nervous system
controls all your
conscious and
automatic actions and
sensations in all parts of
your body such as;
thoughts, feelings,
memories, heartbeat,
blood pressure, body
temperature, breathing
rate and senses….
Central Nervous System (CNS)
Peripheral Nervous System (PNS)
Composed of the brain and spinal
cord.
Composed of the branching web of
nerves to all different parts of the
body.
The nervous system is controlled by
the brain and is connected to the
spinal cord.
Signals or messages flow from these
nerves to the spinal cord, then to
the brain and back again. These
signals are called nerve impulses.
The brain is the control centre. It
receives and sorts out millions of
signals it receives.
The brain sorts out the information
with amazing speed.
The huge network of nerves that run
from the spinal cord to all the
different parts of the body.
Your nerves are like which pick up
signals from all the different parts
of the body.
The nervous system also controls
your breathing, heart beat, body
temperature and actions of your
stomach and intestines.
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If you look at the brain under the microscope, you see a mess of bundles
of nerve cells which looks like long knotted pieces of thread. These
bundles of nerves are your electrical cables.
There are 100 billion of these nerve cells called neurons
These neurons carry and send the electrical signals from the peripheral
nerves to the brain and back again. They can send a message from your
arm to your head in 5 microseconds.
The neuron is composed of a cell body, dendrites and the axon.
The cell body looks like a blob and has an eye called the nucleus.
Coming out of the cell body are fingers called the dendrites and a long
leg.
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A single nerve cell can have 50,000 dendrite branches and can
communicate with 250,000 other nerve cells.
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The long leg connected to the cell body is the axon and looks like a
string of sausages. The axon can be over three feet long.
Three main parts of the brain:
Cerebrum
The cerebrum is the largest part of the brain. It looks like a
wrinkled giant walnut.
There are 2 halves; each half is called a hemisphere. The left
side is the left hemisphere and the right side is the right
hemisphere! The halves or hemispheres are connected to each
other by a wide material called the corpus callosum. Each
hemisphere has an inside layer called the white matter and an
outside layer of grey matter called the cerebral cortex.
The cortex controls your voluntary actions like running and
walking. It is also responsible for body sensations like pain,
learning, and emotions.
Your right side of your brain is connected to the left side of your
body. The left side is connected to the right. This is because the
nerves connecting the brain and the spinal cord cross to the
opposite side.
If you turn the brain upside down, there are twelve pairs of
nerves called cranial nerves that come out from the brain
itself. These nerves have names and also do very important
jobs. For example, the olfactory nerve is the nerve for smell,
and the optic nerve is the nerve for vision.
Cerebellum
Brain Stem
The cerebellum is the
second largest part of
your brain. It is below
the cerebrum and sort
of looks like a ball of
yarn.
The brain stem is on
the top of the spinal
cord. It deals with
very important
functions that keep
us alive.
It's main job is to
coordinate your
movements, posture
and keeping your
balance.
It automatically
controls our
breathing,
heartbeat, blood
pressure, and
circulation.
Damage or injury to
the part of this brain
will make your
movements jerky and
uncoordinated.
If this does not
happen
automatically, can
you imagine what
would happen if you
forget to breathe?
What a catastrophe
that would be!!!
The axon carries nerve impulses from the cell
body to the dendrite of the next neuron.
The neurons do not really connect to each other.
The neurons do not really connect to each other.
When the messages reach the feet of the axon which
are called the axon terminals , the nerve impulse has to
cross a gap so it can reach the dendrite of the next
cell. This gap is called the synaptic gap.
As the messages or nerve impulses arrive at the
synapse, a chemical called neurotransmitter is
released. This chemical acts like a bridge so the
message is passed across the synaptic gap t the
next neuron.
Some nerves are covered by a lining called
myelin sheath.
The sheath around the axon insulates the axon
to speed up the passage of nerve impulses.
Top speed in covered nerves can reach
395 feet per second !!
When you are born, you already have
your whole package of neurons with you.
The bad news is that the human brain
cannot make new neurons.
When they get damaged they die, period.
The good news is that every time you learn
something new, new nerve connections are
made. So the funny thing is the more
tangled your brain, the smarter you are!
Complete the story board
activity to show the stages of
transmission in neurons which
ends with muscle movement