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Slide 1

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Please use as a slideshow to
enable all features…read more

Slide 2

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The Nervous System…read more

Slide 3

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What is the nervous system?
The Nervous System allows the body to
respond to changes in the environment
This change in environment is detected
by receptors in the five sense organs.
Eyes-Light receptors
Ears-Sound and orientation receptors
Nose and Tongue-Chemical receptors
Skin-Temperature and pressure
This process involves neurones and it is
usually coordinated by the brain unless
it is a reflex action.…read more

Slide 4

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Structure of a neurone
Axon Ending
Dendron Cell Body
· Neurones transmit information around the body
· Impulses enter a neurone through the dendrite ending
· Impulses travel through a dendron to the cell body
· The impulse is sent from the cell body through the axon and reaches the synapse
· The myelin sheath is a coating around the axon. It insulates the message so that
the electrical impulse is not lost which makes it travel faster.…read more

Slide 5

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The reflex arc
A reflex action prevents injury. It is an automatic response that is not
controlled by the brain.
·Receptor cells detect a stimulus - change in the environment.
·The sensory neurone sends electrical impulses to the relay neurone.
·The relay neurone sends these impulses to the motor neurone which
sends a signal to the effector.
·The effector produces a response. This could be a muscle or a gland.
Pain receptor Sensory neurone Connecting relay neurone
in finger carries nerve impulse to carries impulse from the
spinal cord sensory to motor neurone.
Motor neurone
carries impulses Spinal
from spinal cord cord
to muscle
Biceps muscle bends arm…read more

Slide 6

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· Where two neurones meet, the gap is
called the synapse.
· The signal is transmitted across this gap
by chemicals released by the neurone,
called neurotransmitters.
· When the electrical impulse reaches
the synapse it triggers the nerve-ending
of a neuron to release the
· These chemicals diffuse across the
synapse and bind with receptor
molecules on the membrane of the
next neuron.
· This stimulates the second neuron to
transmit the electrical impulse.…read more

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Slide 9

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Slide 10

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lisa linsdell


An excellent PP presentation to revise either the nervous system or homeostasis, suitable for any exam board. Higher level. A few revision questions at the end of each of the two sections. 

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