Action Potentials

Question 1

What is hyper polarisation

Answer 1

The membrane potential becomes more negative

Question 2

What is the resting membrane potential for an action potential

Answer 2

-70mV

Question 3

What are ion channels

Answer 3

Protein complexes that span the lipid bilayer to form a central pathway that allows rapid flow of selected ions

Question 4

How are ion channels opened

Answer 4

Membrane voltage - voltage activated channels
Chemical substances - ligand gated ion channels
Physical stimuli - mechanical thermal

Question 5

What are the ion channels responsible for the action potential in neurones

Answer 5

Voltage activated sodium channels ( depolarising)

Voltage activated pottasium channels (hyperporlarising)

Question 6

What is an action potential

Answer 6

Brief electrical signals which polarity of nerve cell membrane is momentarily reversed

Question 7

What is positive and negative feedback in relation to the voltage activated sodium and pottasium channels

Answer 7

The activation of sodium channel self reinforcing opening of few channels causes further ones to open and further depolarisation this is positive feedback

The activation of pottasium channels self limiting outward movement of pottasium this causes repolarisation this is negative feedback

Question 8

What Is depolarisation

Answer 8

The membrane potential becomes less negative