Flatulence

Flatulence is defined in the medical literature as "flatus expelled through the anus" or the "quality or state of being flatulent", which is defined in turn as "marked by or affected with gases generated in the intestine or stomach; likely to cause digestive flatulence." The root of these words is from the Latin flatus - "a blowing, a breaking wind". Flatus is also the medical word for gas generated in the stomach or bowels. These standard definitions do not reflect the fact that a proportion of intestinal gas may be composed of swallowed environmental air, and hence flatus is not totally generated in the stomach or bowels. The scientific study of this area of medicine is termed flatology.

It is normal for humans to pass flatus per rectum, although the amount and the frequency may vary greatly between individuals. It is also normal for intestinal gas passed per rectum to have a characteristic feculant odor, although this too may vary in concentration. Flatus is brought to the rectum by specialized contractions of the muscles in the intestines and colon. The noises commonly associated with flatulence ("Blowing a raspberry") are caused by the vibration of the anal sphincter, and occasionally by the closed buttocks. Both the noise and odor associated with flatus leaving the anus can be sources of embarrassment or comedy in many cultures.

There are 4 general symptoms related to intestinal gas, i) pain, bloating and abdominal distension, ii) excessive flatus volume, iii) excessive flatus odor and iv) gas incontinence. Furthermore, eructation ("an act or instance of belching", colloquially known as "burping") is sometimes included under the topic of flatulence.

Non medical definitions of the term include "the uncomfortable condition of having gas in the stomach and bowels", "A state of excessive gas in the alimentary canal". These definitions highlight that many people consider "bloating", abdominal distension or increased volume of intestinal gas to be synonymous with the term flatulence (although this is technically inaccurate). Colloquially, flatulence may be referred to as "farting", "passing gas", "breaking wind" or simply (in American English) "gas".