Kaplan Nursing Entrance Practice Exam

Saliva plays a crucial role in the digestive process primarily by lubricating food, which facilitates chewing and swallowing. It contains mucus that moistens the food, making it easier to form a soft bolus. This lubrication is essential for moving food through the esophagus and into the stomach smoothly.

In addition to its lubricating properties, saliva initiates digestion. It contains enzymes, such as amylase, that begin the breakdown of carbohydrates. This enzymatic action marks the start of the digestive process even before food reaches the stomach, allowing for preliminary digestion to occur in the mouth.

The other functions mentioned, such as degrading protein, storing food, or filtering toxins, do not accurately describe the primary functions of saliva in digestion. Saliva does not significantly degrade proteins, nor does it serve as a place for food storage, as that takes place in other parts of the digestive system. Although saliva does have some antibacterial properties which may help in maintaining oral health and filtering certain substances, this is not a primary function related to the digestive process itself. Thus, the correct focus on the role of saliva in lubricating food and starting digestion encompasses the essential aspects of its function.