Resting potential (4)

Question 1

Describe briefly the state of an axons membrane when at rest.

Answer 1

• the resting potential is -70mV
• as the outside of the cell is more positive as there are more positive sodium ions outside the cell than inside, it is therefore POLARISED
• the membrane is impermeable to sodium ions
• the membrane is permeable to potassium ions
• the membrane has two channels: the sodium-potassium pump and the potassium ion channel

Question 2

What is the purpose of the sodium-potassium pump?

Answer 2

it uses energy from the hydrolysis of ATP to move 3 Na+ ions into the cell for every 2 K+ ions moved out of the cell.

Question 3

What does the potassium ion channel do?

Answer 3

allows facilitated diffusion of K+ ions out of the neurone down their concentration gradient