the value of threshold can vary according to numerous factors. changes in the ion conductances of sodium or potassium can lead to either a raised or lowered value of threshold. additionally, the diameter of the axon, density of voltage activated sodium channels, and properties of sodium channels within the axon all affect the threshold value. typically in the axon or dendrite, there are small depolarizing or hyperpolarizing signals resulting from a prior stimulus. the passive spread of these signals depend on the passive electrical properties of the cell. the signals can only continue along the neuron to cause an action potential further down if they are strong enough to make it past the cell's membrane resistance and capacitance. for example, a neuron with a large diameter has more ionic channels in its membrane than a smaller cell, resulting in a lower resistance to the flow of ionic current. the current spreads quicker in a cell with less resistance, and is more likely to reach the threshold at other portions of the neuron.