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、胃、小肠、大肠以及。

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.

现在，我们把其余消化道的横截面放大来看，即从食到的部分，其壁通常都由相同的四层组织构成。