resting potential

Question 1

why is the membrane more permeable to K+

Answer 1

• more K+ protein channels
• Na+ only open at high voltages, but K+ channels always open

Question 2

what happens during depolarisation

Answer 2

if potential reaches threshold, more sodium ion channels open and sodium ions diffuse into the neurone

Question 3

what happens during repolarisation

Answer 3

at around 30mV, sodium ion channels close and potassium ions open. the membrane is more permeable to potassium ions, so these diffuse out the neurone, down the gradient

Question 4

what happens during hyperpolarisation

Answer 4

K+ ion channels are too slow to close, so there is slight overshoot where too many potassium ions diffuse out of the neurone.

Question 5

what happens at resting potential

Answer 5

ion channels are reset, the sodium potassium pump returns the membrane to resting by pumping potassium in and sodium out, maintaining resting potential until membrane is excited by another stimulus

Question 6

what happens during the refractory period

Answer 6

acts as a time delay between one action potential and next. this makes sure they dont overlap and limits the frequency at which nerve impulses are transmitted.