Transcript brainText1

It's all
under
control
Getting the message
Humans (and all other organisms)need to respond to changes that
occur both inside and outside their bodies. If they don©t, their
lives can be under threat.The brain is the control centre
of the human body. It receives information from the sense
organs Ð the eyes, ears, nose,tongue and skin. It processes the
information received and sends messages to different parts of
your body. information is carried to and
from the brain through a system
of nerves. The centre of this
system is your spinal cord, which
starts at the base of your brain.
Messages are sent through
your nervous system at speeds of
up to 350 kilometres per hour.
So, it©s not surprising that you
can respond to changes in your
environment very quickly.
Response times are often very
important Ð especially in life or
death situations
1 Which of your sense organs is
involved in helping you keep
your balance when riding a
bike?
2 Think of some situations in
which you have to respond
quickly to changes in your
surroundings in order to
prevent injury or death.
3 How are messages sent through
your nervous system?
4 What activities does your body
carry out without you even
thinking about them?
Map the external regions of the brain
Responding to
external changes
Have you ever wondered how you
can hear, see and duck a ball
speeding towards you all within just
a fraction of a second? Have you felt the
pain when you've ducked too slowly?
Detecting changes in our environment
requires use of our sense organs. Your
eyes, ears, nose, tongue and skin detect
minor changes in your surroundings. If
your organs don't sense a change, you
can't respond, no matter how fast your
nervous system sends messages.
where is the ear drum here?
What%20Is%20H...
inner ear
The human sense organs are supplied with neurons
(nerve cells) to detect and respond to changes that
occur both inside and outside our bodies. The
neurons that detect changes are called sensory
neurons. The parts of the sensory neuron that actually
detect the change are called receptor sites. Each
sensory neuron responds to changes by sending
messages to the spinal cord and (usually) the brain to
interpret and decide what the body should do about
the change. Messages carried through nerve cells are
called nervous impulses, or just impulses.
Neurons in the eyes, ears, nose and tongue respond
to very specific stimuli. For example, the neurons in the
eye respond to light; those in the ear respond to sound
and gravity; and those in the nose and tongue respond
to chemicals. Different types of neuron in skin respond
to temperature, pressure, touch and pain.
Did you
know?
Does it
hurt?
Different kinds of sensory neuron
Sensory neurons are named according to the stimuli
that make them respond. For example:
·· Chemoreceptors respond to chemicals.
·· Photoreceptors respond to light.
·· Mechanoreceptors respond to movement.
·· Thermoreceptors respond to changes in
temperature.
REMEMBER
1. What are neurons?
2. What one name is
given to all of the neurons
that detect change in your
sense organs?
3. What is a receptor site?
4. What does a receptor
do when it detects a
change?
5. What is a nervous
impulse?
6. Copy and complete the
table below.