Final answer:
An increase in the thickness of myelin increases membrane resistance and can lead to faster voltage pulse propagation, but the exact factor increase in speed due to a 252-fold increase in myelin thickness cannot be determined without additional biophysical details.
Step-by-step explanation:
The speed of a voltage pulse in a myelinated axon is determined by the length constant (λ) and the time constant (τ), which relate to the membrane's resistance and capacitance. By increasing the effective thickness of the axon membrane through myelination, the membrane resistance increases. When the thickness of the myelin sheath increases by a factor of 252, this results in a decrease in the leakage of ions across the membrane, which generally increases the speed of the voltage pulse along the axon.
However, to provide a direct answer about the factor by which the speed would increase requires understanding of the detailed biophysical equations governing nerve impulse propagation, which include parameters such as the length constant (λ), time constant (τ), as well as myelin sheath properties. The propagation speed of the voltage pulse is not simply proportional to the increased thickness but also depends on the intricate interplay between the electrical properties of the axon and its geometrical configuration.
Without full access to the specific biophysical model and parameters, it is not possible to give a complete answer to the precise factor by which the speed of the voltage pulse would increase due to a 252-fold increase in the thickness of the myelin sheath. More detailed information regarding the particular biological system and context is necessary for an accurate calculation.