What is the first step in the digestive process that starts in the mouth?

The first step in the digestive process that begins in the mouth is primarily mechanical digestion and enzymatic breakdown. Mechanical digestion occurs as food is chewed by the teeth, which breaks it down into smaller pieces, making it easier to swallow and increasing the surface area for enzymes to act upon. Meanwhile, the salivary glands in the mouth secrete saliva that contains enzymes, such as amylase, which begins the chemical process of breaking down carbohydrates. This combination of mechanical and enzymatic processes is crucial for effective digestion, as it prepares food for further breakdown further down the digestive tract.

The other options highlight processes that occur at different stages of digestion or in different parts of the digestive system. Absorption of nutrients primarily occurs in the small intestine after food has been digested, while the secretion of gastric acid happens in the stomach as part of digestion, but not in the mouth. Transport of food to the stomach is a subsequent step that follows the initial digestion in the mouth, further illustrating that the mechanical and enzymatic actions in the mouth are the foundational first steps of the digestive process.