What is Serosa?
'''Serosa''' (or '''serous membrane''') is a smooth membrane consisting of a thin layer of [[cell]]s, found on the outer wall of the [[organ (anatomy)|organ]]s of the [[abdomen|abdominal]] cavity known as the serous cavity. It secretes serous fluid, and a thin [[connective tissue]] layer. They secrete a lubricating fluid which '''reduces friction''' from [[muscle]] movement. Serosa is not to be confused with [[:en:adventitia|adventitia]], a connective tissue layer which binds together structures rather than reducing friction between them. The serous membrane covering the heart and lining the [[:en:mediastinum|mediastinum]] is called the [[pericardium]], the serous membrane lining the [[:en:thoracic cavity|thoracic cavity]] and surrounding the lungs is called the pleura, and that lining the [[:en:abdominopelvic cavity|abdominopelvic cavity]] and the viscera is called the [[:en:peritoneum|peritoneum]]. The portions of the gastrointestinal tract that do not have a serosa include the esophagus, as well as the middle and distal rectum. [[Category:Animal tissues]]