ch 37 part 2

Part B - Conduction of an action potential along an axon Match the letter of each location along the axon with the correct description of what is occurring at that position.

1. At locationc , the membrane potential changes sign (from a positive value to a negative value) and the voltage-gated K+ channels are open. 2. At locationf , the axon membrane reaches threshold and the voltage-gated Na+ channels open. 3. At location a, the voltage-gated Na+ channels reactivate. 4. At location d, the voltage-gated Na+ channels are inactivating and the voltage-gated K+ channels are opening. 5. At location g, the axon membrane is at resting potential. 6. At location b, the voltage-gated K+ channels are closing. 7. At location e, the membrane potential changes sign (from a negative value to a positive value) and the voltage-gated Na+ channels are open.

Which statement correctly describes what causes the second voltage-gated Na+ channel to open?

After the first channel opens, the movement of many types of ions (both inside and outside the cell) alters the distribution of charges near the second channel, causing it to open.

Part C - Direction of action potential conduction Enter the sequence in which the action potential would pass through the points. Enter the letters in the correct order separated by commas. For example if the order is point (c), then (b), then (a), enter c, b, a. If the action potential would not pass though a point, do not include that point in your answer.

b,a,c

Part D - Conduction speed of an action potentialPart complete There are two properties that affect the conduction speed of an action potential along an axon: the axon's diameter and whether or not the axon is myelinated. Rank the axons from slowest to fastest conduction speed. If two axons have the same conduction speed, place one on top of the other

slowest--- non myelin 20 um diam non myelin 30 um diam non myelin 40 um diam myelin 30 um diam fastest---