Water and ions are absorbed in the large intestine

Peristalsis gradually pushes the contents of the small intestine into the large intestine, or colon. Most of the available nutrients have been removed from the material that enters the colon, but the material contains a lot of water and inorganic ions.

The colon absorbs water and ions, producing semisolid feces from the slurry of indigestible materials it receives from the small intestine. Absorption of too much water in the colon can cause constipation. The opposite condition, diarrhea, results if too little water is absorbed, or if water is secreted into the colon. (Both constipation and diarrhea can be induced by toxins from certain microorganisms.) Feces are stored in the last segment of the colon until they are excreted.

Immense populations of bacteria live within the human colon. One of the resident species is Escherichia coli, a bac-

l| The contents of the rumen— consumed vegetable fiber and intrinsic microorganisms (the cud)—are periodically regurgitated into the mouth for rechewing.

terium popular among researchers in biochemistry, genetics, and molecular biology. E. coli lives on matter that is indigestible to humans and produces some products—such as vitamin K and biotin—that are useful to its host. Excessive or prolonged intake of antibiotics can lead to vitamin deficiency because the antibiotics kill the normal intestinal bacteria at the same time they are killing the disease-causing organisms for which they are intended.

Intestinal bacteria produce gases such as methane and hydrogen sulfide as by-products of their largely anaerobic metabolism. Humans expel gas after eating beans because the beans contain certain carbohydrates that the bacteria can break down, but their human hosts cannot. A large percentage of the mass of feces consists of the cell walls of dead intestinal bacteria.

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Constipation Prescription

Constipation Prescription

Did you ever think feeling angry and irritable could be a symptom of constipation? A horrible fullness and pressing sharp pains against the bladders can’t help but affect your mood. Sometimes you just want everyone to leave you alone and sleep to escape the pain. It is virtually impossible to be constipated and keep a sunny disposition. Follow the steps in this guide to alleviate constipation and lead a happier healthy life.

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