(N/A) The oral cavity performs two major functions: mastication of food and facilitation of swallowing.
Teeth and tongue,with the help of saliva,masticate and mix the food thoroughly.
Mucus in saliva helps in lubricating and adhering the masticated food particles into a bolus.
The bolus is then conveyed into the pharynx and subsequently into the oesophagus by the process of swallowing or deglutition.
The bolus passes down through the oesophagus by successive waves of muscular contractions known as peristalsis.
The gastro-oesophageal sphincter controls the passage of food into the stomach.
Saliva secreted into the oral cavity contains electrolytes $(Na^{+}, K^{+}, Cl^{-}, HCO_{3}^{-})$ and enzymes,specifically salivary amylase and lysozyme.
The chemical process of digestion is initiated in the oral cavity by the hydrolytic action of the carbohydrate-splitting enzyme,salivary amylase.
Approximately $30\%$ of starch is hydrolysed here by this enzyme into the disaccharide maltose.
$\text{Starch} \xrightarrow{\text{Salivary Amylase}, \text{pH } 6.8} \text{Maltose}$
Lysozyme present in saliva acts as an antibacterial agent that prevents infections.