Resting Membrane Potential

 1) What is the distribution on Na⁺ and K⁺ in a neuron at rest?

2) What does the Na⁺-K⁺ pump do?

3) What causes the passive diffusion of Na⁺ and K⁺ when the neuron is at rest?

4) Why is there more K⁺ diffusion then Na⁺ diffusion?

5) Why is the electric potential “–“70 mV

Local Potentials

 1) Where do they occur?

2) Why are they called “local”?  

3) What is meant by describing them as decremental and graded?

4)  What possible changes occur in these local potentials & why?

Action potentials

 1) Where do action potentials start?  Why do they start there?

2) During the resting state, what voltage-regulated gates (VRG) are open and which are closed?

3) How does a local potential initiate an action potential?

4) What happens to the axolemma VRGs when the membrane potential reaches threshold (–55mV)?

5) What ions are moving and in what direction during the early depolarization phase?

6) What VRGs are opening and which are closing during the late depolarization phase?

7) What ions are moving and in what direction during the late depolarization phase?

8) What is the maximum voltage during an action potential?

9) What ion channels are opening and which are closing during the repolarization phase?

10) What ions are moving and in what direction during the repolarization phase?

11) Why does hyperpolarization occur?  What is happening with the potential during this hyperpolarization phase?

12) How does the resting membrane potential get restored?

13) How does the action potential move away from its point of origin? 

14) Why does it move in only one direction?

15) Why is an action potential an all-or-none response?

Answers

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Last revised: Wednesday, 11 April 2007