martes, 2 de octubre de 2007

Digestive System



The gastrointestinal tract (GI tract), also called the digestive tract, or the alimentary canal, is the system of organs within multicellular animals that takes in food, digests it to extract energy and nutrients, and expels the remaining waste. The major functions of the GI tract are ingestion, digestion, absorption, and excretion.
The GI tract differs substantially from animal to animal. For instance, some animals have multi-chambered stomachs, while some animals' stomachs contain a single chamber. In a normal
human adult male, the GI tract is approximately 6.5 meters (20 feet) long and consists of the upper and lower GI tracts. The tract may also be divided into foregut, midgut, and hindgut, reflecting the embryological origin of each segment of the tract.

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