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.
Sneezing is a reflex of the upper airways, activated to explosively discharge irritating material from the nasal cavity. In cats, it is usually caused by the irritation of sensitive nerve endings in the mucous membrane that lines the nose. Nasal discharge is another sign of nasal disease or irritation. Although normal cats may occasionally sneeze or have nasal discharge (similar to human beings), severe, chronic or recurrent bouts of sneezing or nasal discharge suggest a more serious problem. Sneezing and nasal discharge often occur together.