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. Parasympathetic nerves, having centers in the brain stem, stimulate serous and mucous salivary sacretion. Sympathetic nerves inhibit the secretion of serous saliva. The throat and the esophagus transport the food from the mouth to the stomach.