What is meant by “inactivation”? What role does inactivation have on the shape of the action potential? Do K channels exhibit inactivation? What is the reason for your answer? (Could someone explain… this seems like a trick question) Explain why an action potential cannot propagate towards the point of its initiation.
Understand the relationship between membrane resistance and the internal resistance of an axon. How does this explain why larger axons have faster action potential conduction velocities? How would increasing the time constant affect how quickly membrane voltage changes in response to depolarization? Why is action potential conduction velocity faster in a myelinated axon compared to an unmyelinated axon of the same diameter? What are two advantages of saltatory conduction? Why does conduction of the action potential fail in a neuron that has been damaged by multiple sclerosis? Compare the symptoms of MS (multiple sclerosis) with those of ALS (amyotrophic lateral sclerosis). How can the symptoms be explained by the effects of these diseases on the nervous system? MS causes degeneration of the myelin on both sensory and motor nerves. ALS causes degeneration of motor neurons. Would kind of amino acids would you expect to find in the selectivity filter of a Na+ channel: negatively charged, positively charged or neither?
In what fundamental way does the structure of a Na channel differ from a K channel? How are they structurally similar? Is a Ca channel more structurally similar to a Na channel or a K channel? What factor/s account/s for the large number of different types of K channels? Why doesn't a Na+ion pass through the K+channel selectivity filter?
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- Spring '08