adventitia is composed of connective tissue, and the serosa has a layer pf epithelium covering the connective tissue layer. It secretes serous fluid to lubricate the abdominal organs so they move smoothly against each other.
38.6 The muscularis externa of the stomach contains three muscle layers instead of the two found in the remainder of the digestive tract (335). As well as the outer longitudinal layer, and the inner circular layer, there is an oblique muscle layer located innermost between the circular layer and the submucosa. The function of the oblique muscle layer is to add another dimension to the mixing motion of the stomach.
38.7 The epithelium in the esophagus is stratified squamous, and the epithelium in the stomach is simple columnar, so there is an abrupt transition between the two types at the gastroesophageal junction (Bloom and Fawcett, 1968, 544). The esophagus has a stratified squamous epithelium because it transports food rapidly from the pharynx to the stomach and is therefore subject to harsh abrasive forces. The epithelium of the stomach is a secretory and absorptive epithelium, and therefore needs to be a simple columnar layer.
38.8 The large intestine is about 1.5 meters long and begins at the ileocecal junction and ends at the anus (340). The wall of the large intestine has the same structure as other parts of the digestive system with some distinguishing features: there are large numbers of goblet cells, but few villi, and the longitudinal muscle layer is incomplete. Th
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