sternutation

A sneeze (or sternutation) is a semi-autonomous, convulsive expulsion of air from the lungs, most commonly caused by foreign particles irritating the nasal mucosa. Sneezing can further be triggered through sudden exposure to bright light, a particularly full stomach, or as a result of unexpected, climatic variations in one's environment such as rapid changes in temperature and humidity levels.[citation needed]

Sneezing is widely considered to be an agent of disease dissemination in many cultures. Contents [hide] 1 Biological elements 1.1 Overall mechanism 1.2 Epidemiology 1.3 Preventative measures 2 Cultural elements 2.1 Onomatopoeia 2.2 Historic instances and practices 2.3 Traditional responses to a sneeze 3 See also 4 Notes 5 References 6 Further reading 7 External links //

Biological elements

While the function of sneezing is usually assumed to be the expulsion of irritating nasal particles, this may not necessarily be the case. In many individuals, a large part or even the whole of the expulsion of breath may be through the mouth rather than the nose, so that little or no nasal expulsory action occurs. Similarly, the fact that some individuals sneeze in response to the stimulus of cold air on the upper chest, or to bright sunlight, is not easily related to any expulsory function. As in the case of yawning, itching, stretching and hiccups, the functional aspects of sneezing have not been definitively identified.

Overall mechanism

Sneezing typically occurs when foreign particles or sufficient external stimulants pass through the nasal hairs to reach the nasal mucosa. This triggers the release of histamines, which irritate the nerve cells in the nose, resulting in signals being sent to the brain to initiate the sneeze through the trigeminal nerve network. The brain then relates this initial signal, activates the pharyngeal and tracheal muscles and creates a large opening of the nasal and oral cavities, resulting in a powerful release of air and bioparticles. The reason behind the particularly powerful nature of a sneeze is attributed to its involvement of not simply the nose and mouth, but numerous organs of the upper body – it is a reflectory response that involves the muscles of the face, throat, and chest.

An alternative cause of sternutation is sudden exposure to bright light - a bodily attribute known as the photic sneeze reflex. Up to 37 percent of individuals are believed to have this particular genetic trait[citation needed], which is most commonly related to exposure to direct sunlight.

A rarer alternative trigger, observed in some individuals, is the fullness of the stomach immediately after a large