Final answer:
Carbohydrate digestion begins in the oral cavity with the enzyme salivary amylase breaking down starch into smaller sugars. This activity ceases in the acidic environment of the stomach.
Step-by-step explanation:
Chemical digestion of carbohydrates begins in the oral cavity when salivary amylase starts their breakdown.
Carbohydrate digestion initiates in the mouth as food is mixed with saliva from the salivary glands. It's here that the enzyme salivary amylase, also known as alpha-amylase, starts acting on the carbohydrates. This enzyme targets the alpha-glycosidic linkages found in dietary starch, which is a common carbohydrate present in food. As amylase breaks down the starch, it transforms it into smaller sugars like maltose and dextrins. This process continues as the food bolus passes through the esophagus, but ceases in the stomach due to the acidic environment, which deactivates the amylase enzyme. The digestion of carbohydrates by amylase in the oral cavity marks the commencement of the metabolic process known as catabolism, the phase in which larger molecules are broken down into smaller ones for energy.