Use the figure to answer the questions. A) how can you explain the fact of the m

Question

Use the figure to answer the questions. A) how can you explain the fact of the maximum sodium current (INa) occurs during the falling phase of the action potential (not the rising phase)? Be sure to explain how membrane voltage can be falling to the l as positive value even with a high sodium current.
B) during which phase(s) of the action potential do you have increased gNa as compared to when the cell is at resting membrane potential? Na x 9. Use the figures below to answer the following questions gNa Patch Patch H Graph 3) x 05155 y-17251975 Driving force for vs Time Membrane Voltage vs Time IK INa Membrane Voltage minus ENa a. How can you explain the fact that the maximal sodium current (INa occurs during the falling phase of the action potential (not the rising phase)? Be sure to explain how membrane voltage can be falling to a less positive value even with a high sodium current. (6 pts) we nauw maximum sodium cum unnt during he faling Our

Explanation / Answer

The rate of sodium ions entering is graeter in falling phase compared to the rising phase. This is because the sodium ions entering is greater before the action potential peak occurs ie. during membrane depolarisation . During this depolarisation some of the sodium ion channels are only open and hence lesser influx. But after depolarisation action potential drops during repolarisation and hence number of sodium channel opens and greater influx of ions. The applied pulse of current produces an positive current which is outward through the membrane. This current causes the depolarization of the membrane.  Hence the membrane voltage falls even the number of positive sodium ions enter. The gNa increases when the voltage drops , so the voltage drops at repolarisation period. Hence gNa is increases at replarisation period.

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