The Neuron
Key concepts of this lesson:
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2.
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A nerve cell is called a neuron
A neuron consists of a cell body, an axon, dendrites and a myelin sheath
Message transmission between neurons occurs through special chemicals called neurotransmitters
Learning occurs as more and stronger connections are made between neurons
Materials needed:
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Copies of a typical neuron or one from your textbook series or found online
Slides, videodiscs, video clips
Computer with access to Internet
Optional: prepared slides of nerve tissue and microscopes or video-microscope
Pipe cleaners and clear drinking straws
Methods: Briefly review the lessons done to date on the nervous system. If someone called you a "neuron", how
would you feel? To be called a neuron would actually be a compliment, because a neuron is a nerve cell - the kind of
cells in your brain and nerves.
1.
Show students the diagram of a neuron, or pass out their copies (ideally, do both!) Point out the main
structures: axons, dendrites, cell body and myelin sheath. If your students have already studied cells,
you might also point out that the cell body is where most of the organelles are located: nucleus,
mitochondria, etc.
2.
EMPHASIZE the unique shape of the nerve cell - long and thin. Ask students what the main job of a
nerve cell is. (Receiving and transmitting messages.) How does that long, thin shape help it do its job
quickly? An analogy that has worked well with my students is to make a comparison with telephone
wires. What do we use in everyday life to communicate with people across town or across the country?
(Telephone) People (and, increasingly, computers) are able to communicate rapidly and clearly through
the use of telephones. How is the signal sent? Over a long, thin wire. This is a very efficient shape for
message transmission - in the outside world and in our bodies.
3.
In the early 1900s, scientists were astonished to discover that nerve cells do not actually touch one
another, but that there are tiny gaps between nerve cells called "synapses". Neurons produce tiny
quantities of powerful chemicals (neurotransmitters) that are released into the synapse as a message is
being sent from one cell to the next. The neurotransmitter is released by an axon terminal, crosses the
synapse and attaches to a receptor on the other side (in most cases, a dendrite, but synapses are found
on axons and cell bodies too). These neurotransmitters are an important area of study in neuroscience
and scientists are learning more about these amazing chemicals all the time.
(Note: With secondary school students, one might want to discuss the electrochemical nature of the
neurotransmitters as well as different types of neurons and different types of synapses. More
information on neurotransmitters
4.
Another thing that neuroscientists have learned in recent years is that new dendrites actually sprout to
make connections with other neurons, and this is how learning takes place - in the connections between
the neurons! This is very encouraging, because it means that as long as you have neurons, you can
always continue learning, even into very old age. However, to make these connections occur, you have
to continue to have new experiences, whether they be actual experiences or through reading, computer
work etc. This is what school is about: providing new experiences so that new connections can form in
your brains!
5.
Depending on what you want to emphasize, you can go on at this point to one of several different
activities to reinforce this direct instruction.
For this model, each student will need: scissors and pipe cleaners.
To make the model of a neuron:
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Take one pipe cleaner and roll it into a ball. This is will be the cell body.
Take another pipe cleaner and attach it to the new "cell body" by pushing it through the ball so there
are two halves sticking out. Take the two halves and twist them together into a single extension. This
will be the axon.
Take other pipe cleaners and push them through the "cell body" on the side opposite the axon. These
are dendrites. These can be shorter than your axon and you can twist more pipe cleaners to make
more dendrites.
Wrap small individual pipe cleaners along the length of the axon. These will represent the myelin
sheath.
Different colored pipe cleaners can be used to model different parts of the neuron. This activity doesn't take long, but
is a powerful visual picture of a simple neuron. Review what each part represents and what each does. Emphasize
again the long, slender shape with the branches for connections. One class of my students had so much fun with it,
they decided to link all of their neurons together into a long nerve. We hung it up in the classroom and it stretched all
across the ceiling!
6. Depending on your time and resources, you can now make other observations of neurons, either
a.
b.
c.
in the Gallery of Neurons
using prepared slides of nerve tissue and either student microscopes
using slides, videos or videodiscs your school has access to.
7. To model transmission of messages, students can use their bodies as model neurons. Have them pull
one arm up to their shoulder and spread out their fingers to represent the axons. The other arm should
be outstretched, and fingers also spread out. As they connect to one another, they can send a
"message" from one person to another. See if students can point out a drawback of this model. (Our
fingers can't squirt out neurotransmitters between people.)
message transmission or build the
giant rope neuron.
Source: http://faculty.washington.edu/chudler/neurok.html