Increasing axon diameter decreases membrane and intracellular resistance,so it seems the two might cancel each other out in terms of their effect on the conduction speed.Yet,conduction speed is increased by increasing diameter size.Why?
A)Membrane resistance doesn't really affect conduction speed that much.
B)Intracellular resistance doesn't really affect conduction speed that much.
C)Membrane resistance decreases linearly while intracellular resistance decreases by the square of the radius.
D)Intracellular resistance decreases linearly while membrane resistance decreases by the square of the radius.

Question

Quizplus · Accepted Answer

Increasing axon diameter decreases both membrane and intracellular resistance, but the effect of membrane resistance on conduction speed is relatively small compared to intracellular resistance. This is because membrane resistance is only one of two factors that determines the total resistance to current flow, the other being the intracellular resistance. In addition, intracellular resistance decreases more strongly with increasing diameter size than membrane resistance, as intracellular resistance decreases by the square of the radius while membrane resistance decreases linearly. Therefore, increasing diameter size has a greater effect on reducing intracellular resistance and thus increasing conduction speed.

Increasing Axon Diameter Decreases Membrane and Intracellular Resistance,so It Seems