Chapter 8 HW Question & Answers 1. Where do most action potentials originate? a. Initial Segment 2. What opens first in response to a threshold stimulus? a. Voltage-gated Na+ channels 3. What characterizes depolarization, the first phase of the action potential? a. The membrane potential changes from a negative value to a positive value 4. What characterizes repolarization, the second phase of the action potential? a. Once the membrane depolarizes to a peak value of +30 mV, it repolarizes to its negative resting value of -70 mV. 5. What event triggers the generation of an action potential? a. The membrane potential must depolarize from the resting voltage of -70 mV to a threshold value of -55 mV. 6. What is the first change to occur in response to a threshold stimulus? a. Voltage-gated Na + channels change shape, and their activation gates open. 7. What type of conduction takes place in unmyelinated axons? a. Continuous Conduction 8. An action potential is self-regenerating because a.
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- Fall '19