Answer :
Final answer:
Saliva is the watery fluid, secreted by the salivary glands, that contains electrolytes and mucus to help in the initial stages of digestion, particularly in softening and dissolving food particles.
Explanation:
The watery fluid that contains electrolytes and mucus to soften and dissolve food particles is known as saliva. This fluid is secreted by the salivary glands and plays a critical role in the initial stages of digestion. Saliva is comprised mostly of water (≈ 98 to 99.5 percent) and contains essential substances like ions, glycoproteins, enzymes such as salivary amylase and lipase, growth factors, and waste products.
The enzyme salivary amylase is particularly important for initiating the breakdown of carbohydrates. The pH of saliva is maintained between 6.35 and 6.85 through bicarbonate and phosphate ions, ensuring a favorable environment for enzyme activity. Moreover, salivary mucus aids in lubricating the food, making it easier to form the bolus and swallow.