In vertebrates, the digestive tract from the stomach outlet to the anus. The human
small intestine is 6 m/20 ft long, 4 cm/1.5 in in diameter, and consists of the duodenum, jejunum, and ileum; the
large intestine is 1.5 m/5 ft long, 6 cm/2.5 in in diameter, and includes the caecum, colon, and rectum. The contents of the intestine are passed along slowly by
peristalsis (waves of involuntary muscular action). The term intestine is also applied to the lower digestive tract of invertebrates.
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