Incontinentia Buttocks…

Re-reading a post from last term on diffusion and smell inevitably made me think about flatulence. Flatulence is the polite word for farting. Apart from Her Late Majesty the Queen, everybody suffers from flatulence from time to time. Flatus (a Latin word I believe) refers to gases produced in the gut although a hefty proportion of a trump will be the result of swallowed air. There is a condition known as aerophagia (‘air eater’) in which nearly all the gas emitted is from swallowed air. This is a rare condition.

There is even a medical field devoted to the study of flatulence called flatology. So it is proper science and not just an excuse to be rude. Sometimes eructation (belching, burping) is included under the general heading flatulence. Cattle burp a great deal of methane into the air, contributing to the Greenhouse Effect (I have written about it here) and of course kangaroos never break wind (mentioned here).

A normal fart is about 74% by volume a mixture of hydrogen, carbon dioxide and methane produced by micro-organisms in the intestines; usually the large intestine. The smell comes from a variety of sulphur containing compounds such as hydrogen sulphide (H₂S – the bad egg gas). The smell increases from herbivores, through omnivores and then to carnivores who are smelliest of all. This is probably because of their high protein diet, which is rich in sulphur.

Any food that is not completely digested in the small intestine may cause gases to be produced when it reaches the large intestine. It is an environment short of oxygen (anaerobic) so the food gets fermented by yeasts and simple prokaryotes (single celled organisms without a nucleus.) Foods like beans, oats, lentils, onions, sprouts and potatoes contain carbohydrates that are bigger than sugars but less complex than starch. These polysaccharides consist of chains of around ten simple sugar molecules. If they survive the digestive process they make excellent food for the microflora (mostly bacteria) living in the large intestine.

There are various phrases that one might use when in the presence of a friend who has broken wind – the most famous is to exclaim, “More tea vicar?” The above graphic offers a few more possibilities (separated by semi-colons) that you might try if you wish to be more original.

Questions…

1. Name two elements mentioned in the text.
2. Name two compounds mentioned above.
3. Roughly what percentage of dry air is nitrogen?
4. No digestion occurs in the large intestine, so what is its primary function?
5. If a mixture of hydrogen and methane was ignited in plenty of oxygen, what compounds would be produced?
6. Into what is protein digested by the small intestine?
7. Name a disease caused by a bacterium.
8. What is the main role of fibre in the diet?

Have you read this post about selective breeding?

In many cultures breaking wind is considered highly amusing. The video clip is called ‘Pastor Gas – the Farting Preacher’ and features a televangelist called Robert Tilton. He is a fairly unsavoury fellow who used to preach daily on TV in the 1980s telling his viewers to send in money in exchange for prayers and salvation. At his most popular he was earning about $80 million dollars a year. He would speak in tongues as he claimed to be possessed by the Holy Spirit live on television. A few years ago someone made the following video inserting a little fart noise over specific facial expressions. It is no less than he deserves (IMHO).