Here is a bit of nomenclature that may show up in a passage:

The walls along most of the alimentary canal are composed of four cell layers: the mucosa, submucosa, muscularis externa, and serosa. Surrounding the lumen, the mucosa is composed of epithelium, connective tissue and smooth muscle. The submucosa is a zone of nerves, blood vessels, lymphatic vessels, and connective tissues. The submucosa may also contain glands draining onto the mucosal surface. The muscularis externa is a zone of smooth muscle bundles, inner and outer, below the submucosa. The fourth layer, the serosa, consists of fibrous connective tissue and a moist epithelial sheet called the peritoneal covering, which lines the body cavity and all internal organs. Mesenteries are double sheets of peritoneum suspending the digestive organs.