 This video will cover the following objective from Digestive Physiology, describe the mechanisms regulating the secretion of saliva. There are three pairs of salivary glands located just outside of the oral cavity that secrete saliva through ducts into the oral cavity. The parotid salivary glands are the largest salivary glands located just lateral to the masseter. They produce a thin watery saliva that contains a high concentration of the digestive enzyme amylase that initiates chemical digestion of carbohydrates. The most anterior of the salivary glands is the sublingual salivary glands located just inferior to the tongue. The sublingual salivary glands produce a small volume of thick slippery mucus saliva that helps to lubricate the oral cavity. The submandibular salivary glands are inferior and posterior to the sublingual glands located inferior to the mandible. And the submandibular salivary glands produce the majority of the volume of saliva. While this saliva has a thick slippery consistency, it also contains the digestive enzyme amylase. The autonomic nervous system regulates the secretion of saliva while the parasympathetic division of the autonomic nervous system releases acetylcholine to stimulate the secretion of saliva. The sympathetic division releases norepinephrine leading to a decreased volume of saliva secretion. The salivary glands are regulated by a simple reflex initiated by the gustatory receptors detecting food in the mouth. The gustatory receptors relay information in through the afferent pathway in the facial nerve. To the integration centers in the brainstem, the salivatory nuclei in the brainstem include the superior salivatory nucleus and inferior salivatory nucleus. In response to food detected by the gustatory receptors, the superior salivatory nucleus activates parasympathetic efferent fibers in the facial nerve that leads to increased saliva secretion from the submandibular and sublingual salivary glands. And the inferior salivatory nucleus will activate parasympathetic efferent fibers in the glasopharyngeal nerve leading to stimulation of the parotid salivary gland to produce an increased volume of saliva secretion. The salivary glands are also regulated by conditioned reflexes. The processing of information in the cerebral cortex related to food, just thinking about food, smelling food, or seeing food, is relayed down to the brainstem where the salivatory nuclei become activated and send motor commands through the parasympathetic efferent fibers of the facial and glasopharyngeal nerves leading to an increased volume of saliva production.