THE GENERAL STRUCTURE AND DIVISIONS OF THE ALIMENTARY TUBE
THE GENERAL STRUCTURE AND DIVISIONS OF THE ALIMENTARY TUBE T H E alimentary tube is a long continuous tube with an inlet at the mouth and an outlet at the anus . From a functional point of view, it is possible to divide it broadly into three segments. The first segment extends from the inlet of the tube to the middle of the duodenum and may be described as preparatory; here the foodstuffs are mechanically and chemically prepared for presentation to the next segment, but are not sufficiently altered to allow of any absorption. The second segment extends from the middle of the duodenum to the middle of the transverse colon; in it all the main digestive and absorptive processes are accomplished. The third segment, which extends from the middle of the transverse colon to the outlet of the tube, may be described as expulsive; it is almost entirely devoted to the rejection of such portions of the foodstuffs and other waste materials a...
