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Action Potential Propagation in an Unmyelinated Axon (Quiz 2)

Why does an action potential travel down an axon? The basic unit of nerve transmission is the action potential. An action potential is a brief electrical signal that travels along an axon at great speed. The action potential is a rapid change in the relative ion concentrations on either side of the cellular membrane and a rapid return to the original concentrations. The change in ion concentration is called a depolarization of the membrane. The transmission of the action potential is caused by three properties of the system. The depolarization spreads to adjacent areas, the depolarization is self-correcting, and during the recovery period depolarization cannot re-occur. Therefore when an action potential starts it triggers further depolarization but only in the direction along the axon in which depolarization has not already occurred.

View the animation below, then complete the quiz to test your knowledge of the concept.






1An action potential...
A)causes the neuron cell membrane to become unable to alter its charge.
B)causes the outside of the neuron cell membrane to become positively charged in reference to the inside.
C)causes the inside of the neuron cell membrane to become positively charged in reference to the outside.
D)causes the inside of the neuron cell membrane to become negatively charged in reference to the outside.
E)causes the inside of the neuron cell membrane to become neutrally charged in reference to the outside.



2An action potential generates local currents that tend to _____ the membrane immediately adjacent to the action potential.
A)depolarize
B)repolarize
C)hyperpolarize
D)stabilize
E)neutralize



3Absolute refractory period causes...
A)action potential propagation to cease
B)action potential propagation to begin
C)action potential propagation to increase
D)action potential propagation to occur in both directions
E)action potential propagation to occur in one direction



4Action potentials can travel in both directions on the axon.
A)True
B)False



5Threshold is the minimum current required for the cell membrane to generate an action potential.
A)True
B)False







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