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.
Why Cats Sneeze and When to Worry. A sneeze is a reflexive action of the upper airways that serves to discharge an irritant from the nasal cavity. The trigger for sneezing is usually irritation of sensitive nerve endings in the mucous membranes that line the inside of the nostrils.