Action Potential Research Paper

The Action Potential
Graphics are used with permission of: Pearson Education Inc., publishing as Benjamin Cummings (http://www.aw-bc.com)

** If this is not printed in color, it is suggested you color code the ion channels and ions as you go through this topic. Ions channels and ions should be color coded as follows: Red: Sodium ion channels and sodium ions Blue: Potassium ion channels and potassium ions

Page 1. Introduction • Neurons communicate over long distances by generating and sending an electrical signal called a nerve impulse, or action potential.

Page 2. Goals • To understand that rapid changes in permeability of the neuronal membrane produce the action potential. • To recognize
Threshold
|• If the stimulus to the axon hillock is great enough, the neuron depolarizes|• Record the membrane potential as you work through this page: |
|by about 15 millivolts and reaches a trigger point called threshold. | |
|• At threshold, an action potential is generated. Weak stimuli that do not |[pic] |
|reach threshold do not produce an action potential. Thus we say that the | |
|action potential is an all-or-none event. | |
|• Action potentials always have the same amplitude and the same duration. | |
|• At -55 millivolts the membrane is depolarized to threshold, and an action | |
|potential is generated. |
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|• As the neuron is depolarized, the voltage-sensitive gate opens. | |
| | |
|• At a fixed time after the channel opens, it inactivates. | |
| | |
|• At the peak of the action potential, voltage-gated sodium channels begin to| |
|inactivate. As they inactivate, the inward flow of sodium decreases, and the |