Final answer:
Saliva in the digestive system lubricates food for easier swallowing and contains salivary amylase, which initiates the breakdown of carbohydrates into maltose.
Step-by-step explanation:
The role of saliva in the digestive system is primarily to provide lubrication for easier swallowing and to begin the digestion of carbohydrates. Saliva is a watery substance produced by the salivary glands which contains mucus for moistening food, salivary amylase for initiating the breakdown of starches into maltose, bicarbonate and phosphate ions that buffer the food's pH, and antimicrobial agents such as immunoglobulin A and lysozyme. Additionally, lingual lipase initiates the digestion of fats, but carbohydrate breakdown is its key digestive function.