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. The stomach acts like a reservoir. It holds all the food that comes into the mouth during each meal. The stomach does not move all the food it holds directly to the small intestine. Food is moved in small amounts and at regular intervals into the small intestine.