The gastrointestinal tract is made up of the mouth, pharynx, esophagus, stomach, small intestine, large intestine, and finally the anal canal.

消化道的构成包括：口腔、咽、食管、胃、小、及肛管。

Now if we zoom into a cross-section of the rest of the gastrointestinal tract, anywhere from the esophagus till the anus, the walls are typically lined by the same four layers of tissue.

，我们把其余消化道的横截面放来看，即从食管到肛管的部分，其管壁通常都由相同的四层组织构成。