a clinical description
|For students who are reticent about discussion of human waste
products, the following clinical discussion should help overcome in-built aversions
...Bodily functions - especially things that come out of us - seem to create severe embarrassment. So we develop all manner of euphemisms to deal with the topic. Feces probably has more pet names than any other word: caca, poop, doo-doo, number two, BM (short for bowel movement), turds, to name a few. We are even afraid to talk about animal dung, and instead employ all sorts of silly phrases such as cow pies, goat berries and donkey apples.
Clinically, feces are composed largely of materials that could not be digested, together with water, salts, mucus, cellular debris sloughed off from the intestines and bacteria; the remainder is cellulose fiber and other roughage.
Because a large part of feces is not of dietary origin, feces continue to form and are passed even during prolonged starvation.
The brown color is derived from bile pigments which are formed from dead red blood cells. The principle bile pigment is bilirubin, a breakdown product of hemoglobin which is filtered through the liver and then dumped via the gall bladder into the intestines. Consequently, hepatitis or gallstones may alter fecal color, turning the stool grayish-brown. Anemia may also yield a yellowish appearance. On the other hand, a black-tarry stool is indicative of gastrointestinal bleeding, while bright red color is indicative of hemorrhoidal bleeding. Various foods may also lend various hues, such as corn or beets.
The pungent odor of feces results from a cocktail of compounds produced by bacterial action upon residues. Odoriferous bacterial products include indole, skatole, mercaptans, hydrogen sulfide, and ammonia. The most characteristic smell derives from indole and skatole, derived principally from the digestion of the amino acid tryptophan. Specific nuances of odor depend upon an individual's colonic flora and the type of food eaten.
All humans harbor vast hordes of coprophilic (feces-loving) bacteria called E. coli. At any time we carry about seven pounds of bacteria, all busily making gas. It is doubtful we would survive well without our symbiotic guests. E. coli. contributes vitamin K which is essential for proper blood clotting. Additionally, significant amounts of vitamin B-12, thiamine and riboflavin are also produced. As an embarrassing byproduct, almost a gallon of methane gas is also produced per day.
Bacterial flora varies not only from person to person, but also from region to region. Some forms can kill or cause serious illness. Likewise, if they get into other parts of the body, such as the urinary tract, they can cause infections.
Food takes any where from 15 to 30 hours to pass through the entire system. This is called transit time and is strongly correlated to the amount of roughage in the diet. Vegetarians have short ones, heavy meat eaters tend to be extreme. You can measure yours by simply eating a large serving of corn or red beets.
Once swallowed, food is sloshed and churned in the stomach for three to five hours, before being sent to the 20-some feet of the small intestine where it spends another four to five hours. Most of the bacterial degrading is accomplished in the colon, where meals mash into each other and may merge for an additional five to 25 hours.
An average person defecates some seven pounds per day. This amounts to a little over a ton of feces per year. In nature, fungal and bacterial decomposers make quick work recycling it. Occasionally, cave conditions have provided rare opportunities to fossilize ancient human feces. (Dinosaur coprolites, as fossil feces are called, also exist complete with casts of dung beetle workings). Modern anthropologists have taken to examining ancient diets in hopes of finding former food sources which are now neglected.
Feces can provide insights.
Excerpted from Roger's World in the July '95 issue of Coast Weekly: