Question

Myelin wraps and insulates axons, thus increasing the space (length) constant. What is the space constant?

1) A measure of how far along an axon an electrical impulse can propagate without requiring active regeneration by ion channels
2) The distance at which a depolarizing current will spread along a nerve till it decays to 1/3 its original potential
3) The reduction of charge dissipation across the membrane
4) The activation of more distant sodium channels

Answer 1

The space constant is the distance at which a depolarizing current will spread along a nerve till it decays to 1/3 its original potential. Myelin sheath insulates axons, preventing current from leaving the axon and increasing the speed of action potential conduction.

Step-by-step explanation:

The space constant refers to the distance at which a depolarizing current will spread along a nerve till it decays to 1/3 its original potential. It is a measure of how far along an axon an electrical impulse can propagate without requiring active regeneration by ion channels. The myelin sheath insulates axons, preventing current from leaving the axon and increasing the speed of action potential conduction.