A mammalian nerve cell has an axon that extends 3 cm with an inter node spacing

Question

A mammalian nerve cell has an axon that extends 3 cm with an inter node spacing of 2 mm. Calculate the membrane potential just prior to generation of an action potnetial given the following information.

Membrane length constant= 2 mm

threshold= -35 mV

resting membrane potnetial= -60 mV

action potential overshoot= +20 mV

What is the membrane potential at the next node and is the depolarization sufficient to generate an action potential?

What would happen to the conductance of the action potential if the length constant were shortened to 1 mm?

Explanation / Answer

Membrane potential is the voltage difference between the interier and exterier of the cell.

when membrane potential reaches threshold, Action potential is generated.

so here the action potential is generated, so membrane potential is just nearer to threshold or just above it.

for accurate calculation, we need concentration of ions outside and inside of the membrane.

The membrane potential at the next node, will be the same because when action potential generated at the first node of ranvier is in it's full strength.

if lenght constant were shortened to 1 mm, the resistance will be decreased and the conductance will be increased.

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