5.3.6 The Refractory Period

Question 1

What is the refractory period?

Answer 1

• Period of time after action potential where sodium ion channel proteins are closed (during repolarisation) and when potassium ion channel proteins are closed (during hyperpolarisation)
• During this, section of axon membrane is in a period of recovery so it is unresponsive
• Refractory period

Question 2

Why is it important?

Answer 2

• Makes sure action potentials are discrete events, so they don’t merge
• New action potentials generated AHEAD of section of axon as opposed to behind it, so impulses can only travel in a ONE direction
• So minimum time between action potentials at any place in a neurone
• Length of refractory period is key in determining maximum frequency at which impulses can be transmitted along neurones (500-1000 per second)