Nerve Impulse Transmission Model
(Adapted from NABT 1997 convention presentation by Karen Kalumuck of the San Francisco Exploratorium. Also by Roger Schoob of the Woodrow
Wilson Torch Team)
Introduction
A nerve cell or neuron consists of three major anatomical areas. The projections called dendrites
pick up electrical impulses initiated by receptor or from a different neuron as the impulse crosses
the synapse. The electrical impulse then travels from the dendrite to the cell body, then away
from the cell body along a long extension of the cytoplasm called the axon. Axons can be very
long (up to 3 meters in length) depending on the function and location of a particular neuron. The
propagation of a nerve impulse down an axon can be modeled by a row of falling dominoes.
However, freestanding dominoes can be tedious to set up; this model will avoid that issue.
Materials
Dominoes-about 8-10
Masking Tape
Cut, shortened meter stick
Directions:
1. Cut a piece of masking tape about 4-6 cm in length.
2. Apply the masking tape to half of the domino. The other half of the tape should extend beyond
the edge of the domino.
3. Place the first domino near the end of the meter stick.
4. Hold the excess tape so that it extends beyond the edge of the domino at a 90-degree angle. If
applied properly, the tape and domino will act like a hinge.
Directions Part B:
5. After the first domino is placed at the first number mark, place successive dominoes 3 cm apart
using the same tapping technique.
6. To make the dominoes tumble, just touch the first domino.
7. Reset the row by tipping up the meter stick. All dominoes should flip back into place, ready to
be tumbled again.
8. Answer the questions on the student sheet.
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Nerve Impulse Transmission Model: Student Sheet Name
Period
Answer the questions in complete sentences. Use the back of this sheet of paper or your
own paper. Use the diagram if necessary below.
http://media.wiley.com/assets/7/95/0-7645-5422-0_0704.jpg
Use the back of this paper or a separate sheet of paper for the answers to the
Questions and Analysis section
Questions and Analysis: Answer in complete sentences.
1. Observe the propagation of dominoes in a wave. Do all of the dominoes fall at the same
speed (the falling down of the individual dominoes—do they fall at the same speed?).
2. Do the dominoes fall at the same rate? (The time for all of the dominoes to fall)
3. Is there a difference in rate of speed if you push the dominoes harder?
4. Do the dominoes lose energy as they fall?
5. Remove one domino in the middle and try again. What happens? What could this signify?
6. How does pushing the domino beyond its critical angle (tipping point) represent a
generated nerve impulse reaching threshold? What happens to threshold if the domino
does not reach the critical angle?
7. Explain the model in terms of impulse conduction. Explain where resting membrane
potential is located; depolarization, repolarization, synapses, refractory period, and
all-or none- principal and one-way impulse transmission.
8. Does this model represent salutatory or continuous conduction? Why do you think so?
9. Could you redesign this model represent the conduction across a synapse? (This would
use chemical gated channels and be part electrical and chemical). How would the new
design work?
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