Nervous System I - The Neuron_ Generation of an Action Potential Interactive Physiology Worksheet

Nervous System I—The Neuron: Generation of an Action Potential


1. Where is the action potential initially generated?

- The initial segment located at the beginning of the axon is where the action potential is

initially generated.

2. What happens to voltage-gated sodium channels at the threshold?

- The voltage-gated sodium channels will open and close after the membrane’s permeability

to sodium.

3. What happens if there is a weak stimulus at the initial segment, and the threshold is not

reached?

- There will be no action potential because it is an all or none event.

4. What are the names of the two gates on the voltage-gated sodium channels?


- Sodium and potassium channels are the two gates on the voltage-gated sodium channels



5. Just after the peak of the depolarization phase, what happens to the activation and
inactivation gates of voltage-gated sodium channels?


- The activation gate opens just after the peak of the depolarization phase and allows sodium

ions to enter. The inactivation gate closes and prevents sodium ions from entering through

the channel.

6. What happens to the membrane potential during the repolarization phase of the action

potential, and what causes this change?

- It will result from the movement of positively charged K+ ions out of the cell.



7. At the end of the action potential’s depolarization phase, the membrane potential is about 30
mV.