The mucosa is the innermost layer of the GI tract and is made up of the lamina propria , the submucosa and the muscularis mucosae. The myenteric and submucosal plexuses are located in the muscularis mucosa. The muscularis externa is made up of an inner longitudinal muscle layer and an outer circular muscle layer. The contents of the colon are retained in the proximal colon by reverse peristalsis .
Salivary amylase is produced by serous cells only in the parotid gland.
Increases synthesis and secretion of amylase 2. Enhances transport in the ductular epithelium 3. Decreases synthesis and secretion of amylase 4. Decreases blood flow 5. Increases blood flow 6.