Please help with these questions:
1. By what factor would the diameter of the axon have to
change to increase the speed by a factor of 10?
2. Assuming that the time constant doesn't change,
by what factor does the speed therefore change? Why?
Please Help With These Questions 1 By What Factor Would The Diameter Of The Axon Have To Change To Increase The Speed 1 (313.1 KiB) Viewed 23 times
By what factor would the diameter of the axon have to change to increase the speed b a factor of 10? (Note: the "wider axon adaptation" is the strategy adopted by the squid, whose "giant" axons allow very rapid travel of its action potentials, making it a master of the quick escape) What about making the membrane thicker? Wider axons work fine for a squid, but are highly impractical for organisms with lots of neurons like hu- mans. (If each of your neurons were the size of a squid's, your head wouldn't fit through a doorway!). Let's explore another possible way of increasing the length constant and therefore the speed: increasing Rmem by increasing the membrane thickness. This is the strategy commonly adopted by vertebrates. It's achieved by extra insulation (a myelin sheath) that's wrapped around the axon: + Figure 7: Adding a myelin sheath around the axon, effectively increasing the membrane thickness. a) Let's say that myelination increased the membrane resistance by a factor of 1000. By what factor does the length constant increase? Why? b) Assuming that the time constant doesn't change", by what factor does the speed therefore change? Why? Increasing the thickness does increase the Room but it also decreases Cen by the same amount, so the product, RCmem and thus the time constant-remains constant. 13
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