The Nervous System
The Nervous System
What is its FUNCTION?
•  Receives information
about what’s happening
inside and outside the
body.
•  Directs the way your
body responds to this
info.
•  Helps maintain
homeostasis.
The Nervous System
The nervous system is
made up of the:
•  Brain
•  Spinal Cord
•  Network of Nerves that
branch out to ALL parts
of your body
The Brain
Cerebrum
- About 3 pounds
- Size of both
hands together
- 2 halves (left
and right)
- Different parts
of the brain do
different things
Cerebellum
Brain
Stem
A Neuron (Nerve Cell)
AXON
AXON
TIPS
DENDRITES CELL
BODY
Neurons carry information through the nervous system.
There are BILLIONS of neurons in your body.
They are constantly sending/receiving messages.
A Neuron (Nerve Cell)
AXON
AXON
TIPS
DENDRITES CELL
BODY
Direction message travels
AXON – carries the messages
down to the AXON TIPS,
which sends the message to
the next neuron.
DENDRITES – receive
messages and sends
them toward CELL
BODY.
Let’s act it out….
AXON
AXON
TIPS
DENDRITES CELL
BODY
What happens in your nervous system
when you are stung by a bee?
The Nervous System
& our Senses
Let’s
test our
Nervous
systems…
Test Your Reaction Time
How fast do messages travel in your nervous
system?
You will time how long it takes a message to
travel from your EYES to your BRAIN to
your HAND.
Can we make the messages travel faster?
Test your Reaction Time
May 5, 2009
Question: How long will it take for a nerve
signal to travel from your EYES to your
BRAIN to your HAND?
Hypothesis:(Make a prediction!)
Observations & Data Collection:
(Paste your data table into your notebook)
Conclusion Question: What happens to
your reaction time as your practice?
Explain. (Answer the question in your notebook).
Test Your Reaction Time
1)  Hold your thumb and
fingers about 3 cm
apart at the 0 cm end
of a meter stick.
2)  Your partner will drop
the meter stick and
you need to grab it as
quickly as possible.
3)  The faster you grab it,
the lower the
measurement on the
meter stick.
Test Your Reaction Time
4) Use the measurement
on the meter stick to
look up your reaction
time in the table.
5) Repeat the
experiment 3-4
times.
6) What happens to
your reaction time as
you practice?
The Sense Organs
Your sense organs have nerve
receptors that respond to
stimuli (stuff outside the
body) and send messages to
your brain where it is
interpreted.
EYES responds to LIGHT
EARS responds to SOUND
SKIN responds to TOUCH
NOSE responds to SMELL
TONGUE responds to TASTE