8
How does the nervous system work?
Our bodies and health
The
nervous system
is made up of
neurons
. There are
millions of neurons in your brain. Neurons receive
and transmit messages from different parts
of the body to and from the brain.
Neurons
Neurons are star-shaped cells that consist
of a cell body, a long extension called
the
axon
and shorter, thin fibres called
dendrites
. To transmit messages, they
create electrical signals called
nerve
impulses
. These impulses pass messages
from one cell to the next. At the end of
the neuron is the
cell body
. It controls the
neuron and creates nerve impulses. The
axon transmits these nerve impulses to
other neurons. Dendrites receive nerve
impulses from other neurons.
How do neurons transmit information?
Nerve impulses are electrical impulses.
They travel from one neuron to another
neuron along the axon and leave through
the dendrites. The space between one
neuron and another is called a
synapse
.
In order to travel across this space, the
nerve impulse changes into a chemical.
After the chemical crosses the synapse,
it’s transformed back into a nerve
impulse. Then it’s ready to be passed
on to the next neuron.
Some chemicals can
stop messages from
passing to other neurons.
Cobra venom causes
paralysis by stopping the
neurotransmitters from
functioning correctly.
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5
Classify these movements:
voluntary
or
involuntary.
Make a table. Then listen and check your answers.
breathing jumping cycling digesting food
writing blinking sweating clapping
G
E T T I N G S T A R T E D
cell body
axon
dendrites
