ACTION POTENTIALS

Question 1

what are 3 things they are looking for in your answer?

Answer 1

1. Name of ion channel
2. Do they open or close?
3. Movement of ions

Question 2

what is happening at resting potential?

Answer 2

• Na+/K+ pump actively transports 3 Na+ out/2 K+ in

- some K + diffuses back out down electrochemical gradient

Question 3

what is happening at the generator potential?

Answer 3

• a weak stimulus causes some Na+ channels to open so some Na+ diffuses IN
• threshold not reached
• resting potential is restored by the Na/K pump

Question 4

what is happening when threshold reached?

Answer 4

• generator potential reaches threshold so many v-gated Na+ channels open
• Na+ diffuses into axon

Question 5

what is happening during depolarisation?

Answer 5

• V-gated Na+ channels are open and Na+ is diffusing in

Question 6

What is happening during repolarisation?

Answer 6

• voltage gated K+ channels OPEN so K+ diffuses out

- V-gated Na+ channels close

Question 7

what is happening during hyperpolarisation?

Answer 7

the membrane potential is more negative than the resting potential because K+ channels are slow to close

Question 8

what is the refractory period?

Answer 8

• when another action potential cant be started

- ensures they are discrete and unidirectional