Because of the chemical nature of impulse and the axon-dendrite structure. Because of the chemical nature of impulse and the axon-dendrite structure. http://www.biologymad.com/nervoussystem/nerveimpulses.htm (Best technical explanation and excellent graphics and animations)
Newborns may sneeze, and this is typically attributed to the irritation of their nasal passages. The most common irritants, explains Dr. Iannelli, are smoke (and simply smoking outside is not enough), animal dander from pets in the house, dust mites, and mold.
In 2012, researchers figured out why, precisely, we sneeze, and what's supposed to happen when we do. ScienceDaily reported: Much like a temperamental computer, our noses require a reboot when overwhelmed, and this biological reboot is triggered by the pressure force of a sneeze.