The anus from Latin anus meaning "ring", "circle" is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to control the expulsion of feces , unwanted semi-solid matter produced during digestion, which, depending on the type of animal, may include: matter which the animal cannot digest, such as bones ;  food material after all the nutrients have been extracted, for example cellulose or lignin ; ingested matter which would be toxic if it remained in the digestive tract; and dead or excess gut bacteria and other endosymbionts. Amphibians, reptiles, and birds use the same orifice known as the cloaca for excreting liquid and solid wastes, for copulation and egg -laying. Monotreme mammals also have a cloaca, which is thought to be a feature inherited from the earliest amniotes via the therapsids.
What is the average distance food travels through the body (from mouth to anus)?
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The digestive system plays an important role in the absorption of nutrients into the body. It takes the food we ingest, breaks it down mechanically and chemically in the mouth and stomach. It then absorbs nutrients, fats, proteins and water in the intestines before eliminating the waste through the rectum. Major organs involved in the digestive system include the mouth, stomach, small intestine, large intestine, liver, pancreas.
Digestive System: Facts, Function & Diseases
The rectum is a chamber that begins at the end of the large intestine, immediately following the sigmoid colon, and ends at the anus see also Overview of the Anus and Rectum. Ordinarily, the rectum is empty because stool is stored higher in the descending colon. Eventually, the descending colon becomes full, and stool passes into the rectum, causing an urge to move the bowels defecate. Adults and older children can withstand this urge until they reach a bathroom.
Also known as the gastrointestinal GI tract, the digestive system begins at the mouth, includes the esophagus, stomach, small intestine, large intestine also known as the colon and rectum, and ends at the anus. Digestion begins with the mouth. Even the smell of food can generate saliva, which is secreted by the salivary glands in the mouth, contains an enzyme, salivary amylase, which breaks down starch. Teeth, which are part of the skeletal system, play a key role in digestion. In carnivores, teeth are designed for killing and breaking down meat.