Human digestive system secreted by innumerable gastric glands in the stomach, to provide a slimy protective layer against the damaging effects of the chemicals on the inner layers of the stomach. At the same time that protein is being digested, mechanical churning occurs through the action of peristalsis, waves of muscular contractions that move along the stomach wall. This allows the mass of food to further mix with the digestive enzymes. Gastric lipase secreted by the chief cells in the fundic glands in the gastric mucosa of the stomach, is an acidic lipase, in contrast with the alkaline pancreatic lipase. This breaks down
Development of the digestive system from four components: the septum transversum (central tendon), the pleuroperitoneal membranes, the dorsal mesentery of the esophagus, and muscular components from somites at cervical levels three to five (C3–5) of the body wall. Since the septum transversum is located initially opposite cervical segments of three to five, and since muscle cells for the diaphragm originate from somites at these segments, the phrenic nerve, which innervates the diaphragm, also arises from these segments of the spinal cord (C3, 4, and 5). The thoracic cavity is divided into the pericardial cavity and two pleural cavities for the lungs by the pleuropericardial membranes.