Sneeze

Sneezing is a reflux mechanism initiated by irritation on the nasal outer membrane. The irritants stimulate pain fibres in the trigeminal nerve supplying the nasal epitheleum, which transmit afferent nerve fibres the medulla oblongata. Efferent nerve fibres from the medulla oblongata initiate a strong inspiratory effort where in about 2.5 litres of air is inspired. This is followed by strong contraction of the respiratory muscles (including abdominal muscles) building up a high intrapulmonary pressure of about 00 mm Hg. This leads to an explosive outflow of air at velocities reaching upto 965 km/hr.