Action Potential

Question 1

What is an action potential?

Answer 1

A rapid, large change in membrane potential that travels along the axon.

Question 2

What are the three phases of an actio potential?

Answer 2

1. depolarization- Na+ enters, inside becomes more positive (+30mV)
2. repolarization- K+ exits, inside becomes more negative (-70mV)
3. Hyperpolarization- too much K+ leaves, inside drops below -70mV

Question 3

What are the two types of refractory periods?

Answer 3

• Absolute refractory period: No new action potential possible (Na+ channels inactive)
• Relative refractory period: stronger stimulus needed (K+ channels still open)