Action Potential (Principles revision)

Question 1

What does depolarization mean?

Answer 1

Membrane potential become less negative

Question 2

What does hyperpolarization mean?

Answer 2

Membrane potential becomes more negative

Question 3

Describe what happens in an action potential

Answer 3

A stimulus causes depolarization. If this reaches a certain threshold then voltage activated Na+ channels are opened and sodium exits the cell causing further depolarization. This causes a rapid depolarization ( die to positive feedback).
This then causes the opening of voltage activated K+ channels which causes pottassium to enter the cell. The then causes the downstroke of the action potential (repolarization this repolarization then causes the switching off on K+ channels (a negative feedback response) and the resting membrane potential is returned.