The chewed food forms a bolus and when it gets to the back of the tongue it triggers the deglutition reflexes. From the back of the tongue the bolus is pushed into the pharynx where other reflexes move it to the esophagus which moves it into the stomach by peristalsis. There are three pairs of salivary glands. The cheeks contain the parotid gland that secrete a serous juice. The salivary glands are acinar exocrine glands.
Serous saliva contains ptyalin a digestive enzyme and lysozyme and antibacterial enzyme.
Ptyalin, an amylase, breaks down starches. Mucous saliva contains mucin, a glycoprotein, which acts as a lubricant and a glue to clump the chewed food into a bolus for easy swallowing. Saliva contains sodium and some minerals. The brain stem is the area of the brain that activates voluntary and involuntary processes involved with digestion when food is placed in the mouth. The ANS controls saliva formation and secretion.