o The Frog Blog: Biology Prize Entries 2011 - Science of Sneezing

Tuesday, 22 March 2011

Biology Prize Entries 2011 - Science of Sneezing

Sneezing is a convulsive expulsion of air from the lungs out the nose and mouth usually caused by dust particles or something similar irritating the inside of your nose called the nasal mucosa membrane. Some people sneeze when they suddenly come into contact with bright light. One in three people are supposed to do this. Sneezing can also be brought on by a very full stomach or a viral infection such as influenza.

What are the mechanics of sneezing? Once the nasal mucosa is irritated, it produces histamines which affect the nerve cells in the nose causing it to send a message to the brain to sneeze. The soft palate and uvula which are both located on the roof of the mouth depress slightly while the back of the tongue lifts and this partially closes the passage through the mouth so that most of the air is expelled through the nose. Yet because the passage is only closed partially, a considerable amount of air is still expelled from the mouth. when the sneeze is initiated by sudden exposure to light it is called the Photic Sneeze Reflex.

A rare cause of sneezing is because of a full stomach and this is called Snatiation. It is however regarded as a medical disorder passed down genetically. We cannot sneeze in our sleep because our body is in a state where motor neurones (send messages to muscles) are not stimulated and reflex signals are not sent to the brain. This body state is called the REM atonia. However a large enough amount of external stimulants will cause the body to wake and then sneeze.

There are very conflicting estimates at the velocity of the sneeze as it leaves the nose. The most conservative estimates are usually around 150 km/h and these are probably the closest to the truth. Yet the JFK World Health Museum in Illinois claim that a sneeze can travel up to 1000 km/h which seems a bit extreme compared to most estimates.

It can travel up to twelve feet and shoot out approximately 40000 droplets containing around millions of germs. However Mythbusters claim that a sneeze can travel form around half a foot to twenty two feet and that the sneeze speed is closer to 35-40 km/h. This once again shows the conflicting research of different scientists. This still shows that it is important to cover your nose and mouth or on the other hand to remember what other people might be shooting at you.

In history sneezing was thought to signify approaching death. Egyptians, Romans and Greeks saw it as an omen of approaching danger or in a more positive light, a way of telling the future. It was Pope Gregory the Great who is recognised as the man being the traditional words “God Bless You” as he encouraged people to say it during the sixth century plague in Italy.

Sneezing is a disgusting action but a fascinating topic. I hope I have shown the ability of sneezing and the dangers of it. The best way to prevent and viral infection spreading if you don’t have a handkerchief handy is to cover your nose and mouth with your elbow.

Hamish Law, Form IV

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